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  • Life and Medical Sciences  (241)
  • Animals
  • LUNAR AND PLANETARY EXPLORATION
  • 1980-1984
  • 1935-1939  (242)
  • 1925-1929
  • 1938  (126)
  • 1935  (116)
Collection
Publisher
Years
  • 1980-1984
  • 1935-1939  (242)
  • 1925-1929
Year
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 57 (1935), S. 1-29 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two kinds of spermatozoa are formed in the testis of Goniobasis laqueata, typical (eupyrene) and atypical (apyrene); a similar dimorphism is noted in several other related genera. The development of each type of spermatozoon is described in Goniobasis. The apyrene spermatozoa do not appear in the testis until eupyrene spermatogenesis has progressed to the formation of mature eupyrene spermatozoa. After this time apyrene spermatogenesis becomes predominant. It is suggested that this condition is indicative of a modified protandric hermaphroditism, according to a recent theory of spermic dimorphism. The anatomy of the reproductive system of Goniobasis is described briefly, and the behavior and fate of the two types of spermatozoa are noted. Only the eupyrene spermatozoa are inclosed in a spermatophore formed in a special organ of the male, the apyrenes being somehow excluded. Thus the latter do not reach the female in copulation and can have no necessary functional relationship to the ova at the time of fertilization. The delayed formation of the apyrene spermatozoa, and other facts, indicate that they are probably not concerned with the nutrition or transport of the eupyrene spermatozoa.
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  • 2
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 57 (1935), S. 61-89 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Three pairs of thymus primordia are found at 6 to 6.5 mm. on the dorsal lateral ends of the second, third and fourth visceral pouches. Those on each side after fusing by growth and migratin come to lie above the third visceral pouch, whence the thymus migrates upward and backward; growing in size, it stretches above the ends of all the gill pouches. It pushes inward into the mesenchyme at 12 to 13 mm. and becomes perforated and surrounded by blood vessels and connective tissue which separate it almost completely from the epithelium. No septa are found; occasionally the third primordium fails to fuse and forms a separate lobe.The early thymus is a syncytium in which are found lymphoblasts, identified by structure of the cytosome and its behavior during mitosis. Evidence is presented that lymphoblasts migrate into the thymus where they increase in number with corresponding increase in length of cytoplasmic bridges and size of intercellular spaces. At 10 mm. begins a rapid increase in size of the thymus and in number of lymphoblasts and decrease in size of the latter, culminating at 12 to 13 mm. in their transformation into thymocytes. A medulla associated with blood vessels is unmistakable at 30 mm.
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  • 3
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study of the development of the sense organs of the larva of Botryllus schlosseri to determine, if possible, any homologies between its sense organs and those of other types of ascidians such as Molgula and Ammaroucium, which have sense organs structurally very different.The statolith appears in the Botryllus embryo as a single club-shaped cell. The lightsensitive organs have their primordia slightly later as five small filaments, each developed from a ganglion cell. A cavity appears in the statolith into which the light-sensitive filaments penetrate. Later development is concerned with pigmentation of the statolith, and a twisting process which orients it into the position in which it is found in the free-swimming larva. The three tactile papillae develop from evaginations of ectoderm at the anterior end of the embryo. The ectodermal cells at the center of a papilla are differentiated into rod-shaped sensory receptors and ganglion-like masses of nerve tissue. Nervous connections are established between these peripheral ganglia and the central nervous system.Results of the investigation indicate that the statoliths of the different ascidian larvae are homologous; the direction eyes probably are not, but have evolved independently from a light-sensitive area in the primitive larva of a common ancestral ascidian. The larvae of Molgula and Ammaroucium possess no structures comparable to the sensory papillae of Botryllus.
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  • 4
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 57 (1935) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 5
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 57 (1935), S. 335-351 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study of the brinchial epithelium in representative specimens of Cyclostomata Elasmobranchii and Teleostei fishes has been made, with special reference to the following: 1) the importance of physiological role of osmotic regulation effected by the gills; 2) the presence or absence of specialized secretory tissue; 3) progressive evolution of the fishes and the possible phylogenetic difference between them. In regard to these topics we find: 1) There is no indication of any specialization in the branchial epithelium of fishes indicating a special role in extrarenal excretion. 2) In the respiratory epithelium of fishes widely separated phylogenetically or in fishes in living in fresh or salt water, the only significant differences are that in general the teleosts have a squamous type of epithelium, whereas, the elasmobranchs have in general a thicker polyhedral investment. 3) Mucous cells appear large and numerous on the filament proper, smaller and less numerous in the interlamellar spaces, and on the free surface of the lamellae. These are the only specialized secretory cells which occur in the gills.
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  • 6
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 57 (1935), S. 461-471 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The exeretory system of Typhlocoelum cucumerinum consists of three pairs of longitudinal channels communicating by a single ventral vessel with the excretory vesicle. Branches subdivide extensively and anastomose forming a dense network of tubules throughout the body. The vessele possess many of the features characteristic of lymph systems as described in amphistome trematodes. They have cuticular walls, come into intimate association with the intestine and contain a granular coagulum and cellular elements suspended in the lumen. The single system of vessels appears to be functioning as a combined lymph and excretory system. Typhlocoelum americanum Manter and Williams ('28) is regarded as a synonym of Typhlocoelum cucumerinum (Rud. 1809).
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  • 7
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 57 (1935), S. 597-615 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development of the thyroid has been briefly described from an example of each of the four urodele families and comparisons drawn. An attempt has been made toward clarifying previous and conflicting accounts. The thyroid arises as a solid bud from the floor of the pharynx in the region of the first visceral pouches. This bud grows backward until it reaches the pericardium. Division of the primordium into lateral portions is inaugurated and the anterior end of the splitting thyroid loses its connection with the pharynx before the separation of the parts is completed. Some of the undivided anterior portion may persist as an accessory thryroid. After the two lateral thyroid masses are separated the yolk disappears from the cells which then form cell columns and enlarge as a result of the fusion of adjacent vesicles. A thyroid [release] occurs at the time of metamorphosis except in Necturus. After the [release] the follicles refill. Similarities in development and general histological picture are closer between Necturus and Cryptobranchus as a pair than between either of these forms and Amblystoma or Eurycea. Amblystoma and Eurycea also resemble each other in histological picture. It is suggested that Necturus produces the thyroid hormone in sufficient quantity to induce metamorphosis but that some other factor or factors serve to inhibit the response.
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  • 8
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 58 (1935) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 9
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    Journal of Morphology 58 (1935), S. 41-85 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Extensive measurements were made on skeletal configurations and muscles of several forms of Hemiptera-Homoptera from the early nymphal instars to the adults, inclusive. It has been shown that several of the muscles actually decrease in length (i.e., contract) as the animal grows as a whole. Such a state of affairs has never before been observed, so far as the writer knows. The most marked increase in length of a skeletal invagination often coincides with the greatest amount of contracture of the muscle which is attached to its extremity. The characteristics of the arthropod skeleton, which consist of invaginations and evaginations are probably, in the forms studied, due to muscular contraction or to the prolonged sustenance of muscular tonicity.The form of muscular contraction described probably belongs to the ‘catch’ type rather than to the metabolic type. The direct cause of these muscular contractions is probably due to changes in physico-chemical constitution of the haemolymph.
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  • 10
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 58 (1935), S. 173-188 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The tubules vary in number from about 190 to 300. They gather into twelve groups each consisting of an anterior and a posterior division and each emptying into one of twelve ampullae arranged equi-distant from each other about the wall of the posterior mid-gut and in a transverse plane just anterior to the sphincter muscle which marks, externally, the junction of mid- and hind-gut, that is to say, the ‘pyloric valve.’ The lumen of each ampulla is continuous with one of twelve furrows formed by the gathering of the hindgut epithelium into as many folds.The wall of the digestive tube is made up of, (1) an inner epithelium (tall columnar cells), (2) an intermediate connective tissue layer, and (3) an outer muscular coat (inner circular and outer longitudinal layer). The mid-gut epithelium dips down at frequent intervals to form crypts at the bases of which are the ‘regeneration centers.’ This epithelium is covered, on its luminar surface, by a curious striated border. The epithelium of the hind-gut appears to be covered by chitin.A malpighian tubule consists of a single layer of large polygonal cells with indistinct borders. It is covered externally by a thin membrene made up of ‘peritoneal cells’ and internally by a striated border similar to that in the mid-gut. Spiralling about each tubule from origin (free end) to insertion (in the gut) is a slender tracheole.
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  • 11
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The flexures in the flexed-tailed mouse consist of unilateral fusions of adjacent vertebrae. Fusions, if complete, produce straight stiff segments.In normal mouse embryogeny, the precartilage cells surrounding the developing nucleus pulposus of the embryonic intervertebral disk in the proximal tail region begin to elongate and become fiber-like at about 14 days after fertilization. In the flexed mouse, such differentiation fails to take place on one side of an affected disk, and these cells develop through cartilage to bone. At such a point there is frequently a bend in the notochordal axis. Other abnormalities of the notochord have been observed. These are not the cause of the flexures.The gene for flexed tail also produces two effects more general in their expression. First, it slows the growth of the vertebral column as indicated by the shorter vertebrae of the proximal tail region. This is observable 13 days after fertilization. Second, it produces an embryonic anemia which is already in existence at 14 days after fertilization. It is postulated that the flexures are due to the retardation of growth at a time which is critical for the intervertebral disks. Whether this retardation is the primary effect of the gene and produces the anemia, or whether the anemia is primary and produces the retardation, the data do not show.
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  • 12
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 58 (1935), S. 279-284 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The histological structure of the eye of the monotreme, Echidna hystrix is described with reference to its comparative relationships. The eye is primarily mammalian in character but its choroid contains a definite cartilaginous plate and its retina is anangiotic.
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  • 13
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 58 (1935), S. 555-571 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Each contractile vacuole system of Paramecium multimicronucleata is made up of a number of components, some temporary and others permanent. The contracting vacuole with its membrane is a temporary structure as are the vesicles which fuse to form it. The vacuole discharges its contents to the exterior leaving a vestige closing the pore. The pore, with its discharging tubule and the feeding canals are permanent cell organelles. The feeding canals end in injection tubules which extend up to the pore. The vesicles, which later fuse to form the vacuole, are formed at the proximal end of the injection canals, leaving a membrane closing the canal, much as a food vacuole is formed at the gullet. The canal-fed contractile vacuole of Paramecium is very similar to the vesicle-fed vacuole of Euplotes both as to its origin and its fate. The Nassonov homology is rejected.
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  • 14
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 57 (1935), S. 473-499 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The hypoglossal downgrowth is initiated at about the twenty-somite stage, as ventral extensions from the postotic (occipital) myotomes 3 and 4. At thirty somites, occipital myotomes 2, 3 and 4, and cervical 1 have developed ventral processes. These descending processes with contributions from posterior myotomes later form a common condensed area below myotomes 2 to 7, the submyotomic tract. There develops from this a cord of mesoderm, the hypoglossal cord or downgrowth.The anterior postotic myotomes are classed as indirect (numbers 1, 2, 6 and 7) or direct (numbers 3, 4 and 5) contributors to the hypoglossal downgrowth.Mechanical factors associated with this growth process are discussed.The hypoglossal nerve at 75 hours has six roots, four occipital (numbers 1 to 4) and two cervical. The first two occipitai roots fail to keep pace in development and are subsequently lost. A transïtory connection of the third cervical to the hypoglossal nerve is demonstrated at the age of 5 days. At 6 days the first occipital root is reduced to scattered fibers, the remaining occipital roots, numbers 2 to 4, increase in size, cervicals 1 and 2 join the hypoglossa.The correspondence of the myotomes providing the contributions to the hypoglossal cord and the nerves providing the major contributing roots of the hypoglossal nerve is commented on.
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  • 15
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    Journal of Morphology 57 (1935), S. 501-531 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study is presented of the most anterior postotic somites in a series of embryos from the five-somite stage to 16 days. A gradual fading out of the somite forming tendency in this region seems to be indicated both by the formation of a rudimentary somite and by conditions found in the first true somites.There are, in the rabbit, three occipital somites, all of which form myotomes. The fate of the myotomes is traced until their identity is lost in the formation of definitive muscle masses.From the sclerotomes two occipital arches, comparable to those of vertebrae, are formed and can be identified as late as the time of beginning chondrification. There is a marked compression of the tissues in this region, the sclerotomal material being not only relatively but actually shorter in older embryos. This compression results in, 1) the approximation of the hypoglossal roots, and, 2) the fusion of the two occipital arches.The cartilaginous basal plate in rabbits begins development at its caudal end and differentiates anteriorly from this with little evidence of a primitive segmentation except as this posterior first center might be called a segment.
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  • 16
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The female black scale possesses a pair of lateral ocelli. Each develops as a small disc of enlarged hypodermal cells which increases in size and invaginates. The disc finally becomes cut off from the hypodermis to form a vesicle lying between the regular hypodermis and the lateral margin of the brain. The vesicle becomes differentiated into two parts. The outer group of cells forms the vitreous body, the inner group gives rise to the retina. The vitreous body soon begins to secrete the lens which, during embryonic life, becomes biconvex. Pigment granules form only in the retinal cells; at first yellow, later black. The ocellus of the first instar is similar to that of the embryo. During first and second ecdyses the old lens is cast off and a new one secreted by the vitreous body. A large, irregularly shaped crystalline body forms between the vitreous body and the retina. The ocellus is of four parts: lens, vitreous body, crystallin body and retina. Retinal cells are at first nucleated but the nuclei probably pass to the nerve fibers each one of which is connected to a retinal cell. The ocellus does not change in structure throughout the life of the insect but finally disintegrates. The disintegration begins on the inner surface of the lens. Ocelli developed in the embryo remain unchanged throughout the insect's life.
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  • 17
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This article describes the structural features of the mantle and shell, particularly in the tiger snail, Anguispira alternata. The shell and the slime appear to be secreted simultaneously, probably from the same sources, and except for the mucus probably from the same materials, but certainly through very different structures.It is found that all the layers of the shell are secreted in a liquid or semi-liquid state by some part of the mantle. The periostracum is secreted from the supramarginal groove as a liquid which soon toughens as viscosity increases until it forms the organic covering of the shell. The inner layers are derived from epithelia beneath the shell, crystallizing out of a semi-liquid mass into the characteristic patterns, which we recognize as the layers of calcium carbonate. This process is traced from the synthetic viewpoint in the secretion from the mantle, also some of the stages can be detected from the analytic standpoint in the breakdown of shell materials.Some phases of the above structural states can be recognized in living mantles. A chemical analysis of the shell is also given.
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  • 18
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    Journal of Morphology 58 (1935), S. 87-115 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: From the first larval instar until the time of the final transformation into the adult the thoracic muscles are numerically the same. The muscles increase in fiber number with the growth of the larvae. There are two types of larval muscles: a. functional (striated and of considerable diameter) b. non-functional (unstriated and of narrow diameter). The non-functional muscles are mainly the prospective wing muscles of the adult. They grow most in diameter at the time of the final transformation. The positions of attachment of both types of muscles undergo no marked replacements during transformation, although the skeletal parts to which they are attached may become greatly modified. The larva has numerically more muscles than the adult. Extensive obliteration of the trunk leg muscles and of some neck muscles takes place. The intrinsic leg muscles of both the larva and the adult are the same.There are no anlagen of the adult muscles in the larval labium, and myoblasts probably form the adult musculature of this organ.The wing muscles of adult Anisopterid dragonflies insert close to the articulations of the wings on apodemes arising from membranes, or on discs arising as internal invaginations of detached, lateral, tergal plates.During the metamorphosis of its musculature, a dragonfly exhibits every essential phenomenon that a so-called ‘holometabolic’ insect does.
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  • 19
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    Journal of Morphology 62 (1938), S. 91-111 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The clam Mya differs from other pelecypods which have been investigated in this respect in having most of the reserve nutritive materials formed within the vacuolated follicle cells of the gonads instead of within the very limited amount of mesenchymatous connective tissue of the visceral mass. The profusely branching tubular gonads originate from two groups of primordial germ cells situated in the position of the future genital apertures. The germinal primordia soon become differentiated into two types of nuclei, one of which becomes associated with the large, vacuolated follicle cells, which form the principal volume of the gonadal tissue, while the other type proliferates to form the primary gonia which become widely scattered along the walls of each alveolus.There is much degeneration and cytolysis during gametogenesis in both sexes, with the accumulation of characteristic inclusions within the follicle cells. Atypical spermatogenesis followed by cytolysis occurs throughout the year but the normal method only in preparation for spawning. No evidence of protandry or change of sex was obtained; only three hermaphrodites were found in the examination of more than 1000 individuals.
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  • 20
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    Journal of Morphology 62 (1938), S. 1-2 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 21
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The regeneration of muscle in larval Amblystoma punctatum is preceded by an extensive dedifferentiation of the old muscles of the limb stump. The process of muscle dedifferentiation consists in a separation of muscle nuclei, surrounded by a small amount of cytoplasm, from the injured ends of the muscle fibers. The dedifferentiation of the cut muscles of the limb stump progresses proximad as far as the origin of the muscles on the humerus and results in a complete transformation of these muscles into undifferentiated cells which appear to contribute to the formation of the regeneration blastema. Shoulder muscles, which were attached to the humerus, also undergo a partial dedifferentiation when their points of insertion on the humerus are destroyed by the degeneration of the perichondrium. These muscles never dedifferentiate, however, for more than one-fourth their original length. The process of dedifferentiation in the shoulder muscles is similar to that found in the cut muscles of the limb stump.The regeneration of the injured muscles occurs in two ways. The shoulder muscles reconstitute themselves by means of terminal and lateral sarcoplasmic buds formed near the distal regions of the muscle fibers. The muscles of the limb proper, distal to the shoulder, differentiate out of local aggregations of blastema cells. No myoblasts were observed.The regeneration blastema arose chiefly from dedifferentiated cells of muscle, nerve connective tissue sheath, perichondrium and cartilage.
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  • 22
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    Journal of Morphology 62 (1938) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 23
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    Journal of Morphology 62 (1938), S. 177-218 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The original innominate bone consisted of ischiopubis only. From this developed a dorsally-directed ilium, upon which the dorsal limb muscles, originally arising from fascia, settled, and which thrust dorsalward between roots of the limb plexus, thus dividing the nerves into prozonal (dorsal and ventral) and metazonal (dorsal and ventral) groups. The primitive muscles of the tetrapod hip and thigh comprised a dorsal mass, soon divisible into sheets, innervated by both prozonal and metazonal dorsal nerves, and a similar ventral mass comparably innervated. The original two elements thus became four basic elements, and probably in early mammals or mammal-like reptiles all dually innervated muscles split into singly innervated units. With this four-group basis as the chief criterion, but considering other factors as well, it is possible to homologize the muscles of urodeles (ventral components only), lacertilians, mammals, and birds in entirely satisfactory manner, except for doubt in several instances in which specialization has secondarily obscured the precise relationships. In different mammals there is shown a tendency toward a final fusion of certain unrelated muscle units (biceps plus gluteus longus, human type of biceps, adductor magnus, and tensor fasciae femoris with gluteus maximus).
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  • 24
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    Journal of Morphology 62 (1938) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 25
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    Journal of Morphology 62 (1938), S. 415-443 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the blastula stage the roof of the subgerminal cavity is composed of an irregular layer of cells, the nuclei of which lie in the upper or middle part of the cytoplasm.On the floor of the subgerminal cavity groups of already degenerating cells occur. They represent the vegetative pole of the blastula. Almost every cell contains glycogen, and mitotic cells show no special orientation.In the gastrula stage the cells of the area pellucida become regularly arranged as a single-layered, cylindrical epithelium with basally situated nuclei.The yolk endoderm cells are formed from the proliferating upper layer of the area opaca.The embryonic endoderm is formed at the posterior end of the area pellucida by outgrowth of single cells from a circumscribed area, the primitive plate.This plate eventually bends inward to form a typical archenteric canal, through which endoderm continues to invaginate from the epiblast.The endoderm spreads in a cranial and lateral direction until it has formed a complete layer.The epiblast cells lose their glycogen as they invaginate to form endoderm, which is free of glycogen.In the area opaca the upper layer and the yolk endoderm contain glycogen.The mitotic cells of the epiblast of the area pellucida are always orientated horizontally, but in the primitive plate and archenteric canal they are orientated vertically as well.
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  • 26
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    Journal of Morphology 62 (1938), S. 559-597 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The larval, metamorphosing and definitive aortic arches of Desmognathus fuscus, Plethodon cinereus, Eurycea bislineata, and Gyrinophilus porphyriticus, described in this paper, were investigated because it was thought possible that, if the fourth or pulmonary arch failed to develop in these lungless forms, a new factor associated with the loss of lungs might be revealed.The salient points of structure disclosed, so far as the problem involved is concerned, are: D. fuscus and P. cinereus develop fourth arches which remain functional in the larvae and adults and supply the pharynx, oesophagus, stomach and skin of the shoulder region. In some instances the fourth arch in the larvae of P. cinereus is reduced in length or entirely lacking in which cases correspondingly less of the fourth arch and more of the third arch is present in the adult. E. bislineata and undoubtedly G. porphyriticus fail to develop fourth arches and hence do not possess these in either the larval or adult states.It is concluded, therefore, that the failure of the fourth arch to develop has evidently not been a factor involved in the advent of lunglessness in plethodontid salamanders. Also, the fact that E. bislineata never develops a fourth arch, yet is able to transform, furnishes additional evidence against Figge's view that Necturus fails to metamorphose because the ventral portion of the fourth arch is absent.
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  • 27
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    Journal of Morphology 63 (1938) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 28
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    Journal of Morphology 63 (1938), S. 75-86 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study is based on serial sections of the occipital and otic regions of a therocephalian from the Tapinocephalus zone. The occipital region as preserved consists of the basioccipitals and exoccipitals. The basioccipital is long and slender and is separated from the more anterior basisphenoid by an unossified zone. The exoccipitals are large and contain a part of the jugular foramen and two foramina for cranial nerve XII.The otic bones are fused together to form a periotic. The most striking feature of the inner ear is the medioventral position of the vestibule. Passing back into the periotic from the vestibule is a deep recessus scala tympani. This recess opens anteriorly into a ventral fenestra in the vestibule, the fenestra rotunda. These structures are similar to those of Dimetrodon and the gorgonopsian.The anterior part of the periotic is projected ventrally to form a basicranial process. This probably arose by intramembranous ossification. The unossified zone between the basioccipital and basisphenoid may represent a persistent basicranial fenestra.
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  • 29
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    Journal of Morphology 63 (1938), S. 63-73 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study has been made of the growth of the eye anlage, and of the increase in number of the elements of the dioptric system of larvae of Drosophila melanogaster.In newly hatched larvae the eye rudiment grows fast, but slows down later and becomes nearly stationary during the second half of larval life. The increase in number of elements in the eye disc parallels the growth of the whole anlage and reaches a maximum about 70 hours after hatching. The imaginal disc cells increase in number but not in size, in contrast to other larval cells which increase in size but not in number.
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  • 30
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    Journal of Morphology 63 (1938), S. 87-117 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The form of the vertebral column is definitely related to its function as a supporting rod, a base for attachment of body and limb muscles, and a protection of the spinal cord and nerves. Primitively composed of a series of simple undifferentiated blocks, it progressively becomes complicated through development of articular processes giving added strength and greater mobility. Simultaneously, the centrum and the neural arch become adapted to withstand tension and compression stresses which vary with the movements possible in different regions of the column. These movements are partially determined by the plane of the zygapophyses and the nature of the intercentral articulation, together with the action of the axial muscles and ligaments.In fish and primitive tetrapods the axial musculature serves as the chief locomotor organ and consists of a series of myomeres extending with little interruption from the head to the tail. In tetrapods the locomotor function is taken over by the limbs and the axial muscles become progressively differentiated into long flexors and extensors of the column and gradually lose their external segmentation.
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  • 31
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    Notes: Adult salamanders of Ambystoma tigrinum show a high degree of sexual dimorphism. The normal growth of the urogenital ducts system in relation to the development of the gonads is traced from the sexually indifferent period preceding metamorphosis to sexual maturity at 1 year. Differentiation and growth of secondary sex characters is correlated with spermatogenesis in the male and with growth of ovocytes in the female.Testicular hormone manifests its initial appearance in male differentiation of the wolffian and urinary collecting ducts following metamorphosis. Growth of ovocytes and oviducts begins before metamorphosis and may be assumed to indicate the initial appearance of the ovarian hormone. Females retain the larval arrangement of wolffian and urinary ducts. The oviducts of the male regress during the period of rapid male differentiation. This suggests the possibility of antagonistic activity of the male hormones in Ambystoma.
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  • 32
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    Journal of Morphology 63 (1938), S. 143-161 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A batch of fifty newts was subjected to complete food deprivation for a period of 4 months. During the experiment twenty-two individuals died and twenty-eight were killed at intervals. From the end of the second month the erythrocytes began to show in increasingly greater numbers a progressive alteration in the nucleo-cytoplasmic ratio. The nucleus of these atypical erythrocytes gradually enlarged and ultimately occupied the entire cytosome. Meanwhile the nuclear reticulum became extremely fine and closely meshed, eventually appearing practically homogeneous and relatively chromophobic. The end result was complete dissolution. The leukocytes became greatly reduced in number, the eosinophils disappearing completely. The neutrophils and basophils were agranular in the blood smears. The erythrocyte transformations represent late results of a chain of factors: cytoplasmic hypotonicity, nuclear endosmosis, attenuation and fenestration of nuclear membrane. The subcapsular lymphogranulocytopoietic tissue of the liver had almost completely disappeared. The spleen was greatly reduced in size; it was essentially lymphoid in character and erythrocytopoietic activity had ceased practically completely. Complete restoration of normal conditions in blood, liver and spleen was effected by the end of 2 weeks by feeding with earthworms. The regenerating blood showed many naked nuclei of disintegrating atypical erythrocytes, many immature erythrocytes in mitosis, increased number of small lymphocytes (lymphoid hemoblasts), large but variable numbers of microcytes, many giant thrombocytes and normal granulocytes.
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  • 33
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    Notes: Colloidal carbon injected into the coelom of the larval lamprey, Ammocoetes, is taken up directly by the pronephric tubules. Due to the absence of nephrostomes the mesonephric tubules do not function in a similar way. The tubules of neither show any intracellular deposition of carbon. The reticular elements which support both these kidneys exhibit pronounced phagocytic and hemocytopoietic activity. Carbon in either a free or included form reaches all the other organs both as a result of direct invasion or secondary distribution by the vascular system. The liver is the only organ whose vascular endothelium exhibits cytopoietic properties. To the diffuse spleen as a site of blood cell formation thus should be added the reticular tissue of the pronephros and mesonephros and the vascular endothelium of the liver. Playing a minor role in a similar way are the intestinal mucosa exclusive of that in the typhlosole and the spongy tissue dorsal to the neural tube.
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  • 34
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    Journal of Morphology 63 (1938) 
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  • 35
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    Journal of Morphology 63 (1938), S. 181-205 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In an earlier paper (Slifer, '37) experiments were reported which showed that in Melanoplus differentialis eggs the hatching enzyme, which destroys the white cuticle, is secreted by the pleuropodia (appendages of the first abdominal segment of the embryo) during the last few days of incubation. In the present report the development and differentiation of the pleuropodia, together with the cytological changes which occur in them before, during and after they become functional, have been followed. The time at which the secretion granules are discharged from the pleuropodial cells was found to be closely correlated with the time at which the tough, white cuticle begins to disintegrate. The cytological evidence, then, supports the author's earlier conclusion, based upon experimental work, that the pleuropodia secrete the hatching enzyme.
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  • 36
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    Journal of Morphology 63 (1938), S. 207-217 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Comparison of intramembral and trunk/limb proportions in the roadrunner (Geococcyx) and two related genera of cuckoos (Coccyzus and Crotophaga), together with a consideration of their habits of locomotion, lead to the following two generalizations: (1) The incipient cursorial leg of more primitive, arboreal birds, with the metatarsus shorter than the femur, is not an efficient mechanism for bipedal terrestrial locomotion. The direct adaptation to the cursorial habit in terrestrial birds lies in the further elongation of the whole leg, the distal segments undergoing a relatively greater elongation than the femur; the greatest degree of elongation is shown by the most distal segment. (2) When the development of terrestrial, cursorial habits in birds leads to diminished use, or discuse, of the wings as organs of locomotion, the wing skeleton becomes reduced in length; each segment of the wing is reduced, but the degree of reduction is greatest in the more distal segments. It is probable that reduction appears first in the most distal segment and later successively in each segment proceeding proximally therefrom.
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  • 37
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    Journal of Morphology 63 (1938), S. 219-227 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: The median cord arises as a hypodermal invagination along the midline from stomodeum to end of tenth abdominal ganglion. It separates from the hypoderm, but does not differentiate into any tissue; apparently it degenerates.
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  • 38
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    Notes: There are 19 chromosomes in diploid cells of male Paratylotropidia brunneri; of these, four are V-shaped multiples. There are twenty chromosomes in diploid cells of females; of these, four are V-shaped multiples. If the two arms of each multiple are counted as separate chromosomes, we have the usual number of chromosomes for the Acrididae, i.e., twenty-three in male and twenty-four in female.There are nine chromosomes in the first spermatocyte divisions: seven tetrads, one octad and a decad. The latter is made up of the accessory chromosome associated with an octad.One of the V-shaped multiples in the male is limited to that sex. The homologue of one of the dyads of which it is composed is a free dyad, the homologue of the other forms a V-shaped multiple with the accessory chromosome. The V-shaped multiple limited to the male shows differential heteropycosis in the prophases of the first spermatocyte. There is evidence that its homologous parts are isolated from each other as far as crossingover is concerned.A study of the first maturation division of the heterogametic sex is essential for the identification of the sex chromosome.
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  • 39
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    Journal of Morphology 63 (1938), S. 229-261 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Although thoracic diverticula of the aorta ending dorsally in pulsatile organs were discovered by Brocher as early as 1917 no detailed account of their structure was published. The condition of these structures in the adult was not investigated and their development through larval instars was not followed. Brocher's later papers announced the discovery of similar organs in the orders Orthoptera, Coleoptera and Lepidoptera. In 1931 E. Meyer described in some detail pulsatile organs in the Ephemerida. In general these accounts are either superficial or of doubtful interpretation.The present paper deals with the Odonata and stresses the Anisoptera. Anax junius has been studied as the type both anatomically and histologically in all stages of larva and imago except the first four instars. Other types have been compared with Anax, and some of the other orders mentioned have been checked for presence and nature of these organs.Aortic diverticula and pulsatile organs occur in all Odonata both larval and adult. These are derived from the same origins and their histology is that of the membranes involved in aortic and body walls. Through inference from morphology and from physiological examination it appears that pulsatile organs (1) supplement heart action, perhaps substituting for it during emergence. (2) assist in the functioning of the ostia and ostial glands, and (3) may even be important in production and distribution of hormones.
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  • 40
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    Notes: The germinal epithelium was studied in an effort to determine its role in postpubertal ovogenesis. Active and inactive areas of epithelium were observed regardless of the oestrous periods. The active areas, exemplified by numerous mitoses and a frequent stratification of the epithelium, are foci for egg cell production.Egg cells are produced from the germinal epithelium by: activation, migration and transformation of single germinal epithelial cells; migration and differentiation of nests of cells; ingrowths of cords of cells.Young ova in the cortex of the ovary are at first surrounded by a single layer of flattened follicular cells of germinal epithelial origin. In the subsequent development of the follicle stratified layers make their appearance. The zona pellucida appears as a well-defined structure coincident with the stratification of the follicular layers.The follicular cavity develops as a split between the follicular cells at one side of the follicle. In the mature follicle the cavity is broad and contains liquor folliculi. The theca interna and externa are not distinguishable until the follicle is highly cellular.
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  • 41
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    Notes: The spermatogenetic cycle of the testis of the musk turtle is limited to the summer months of the year, and closely parallels that of the anuran Amphibia. Spermatozoa are present in the testis from September to May, and breeding may occur in either fall or spring. A pronounced increase in the size of the epididymis and a corresponding decrease in the size of the testis occurs at the end of the cycle (September).During the months of March, April and May, all spermatozoa are eliminated from the seminal tubules, and the germinal epithelium is built up in preparation for spermatogenesis. Spermatogonial divisions occur in small numbers in May, and the division tempo increases during June. Primary spermatocytes and maturation divisions appear after the middle of June, and continue through July and August. Spermiogenesis begins in late July, is in full progress in August, and is practically completed by October. Laboratory specimens usually show an active spermatogenesis in winter, but it is not probable that a second spermatogenetic cycle occurs in specimens under normal hibernating conditions.No seasonal changes are observed in the interstitial cells of the testis, and no seasonally variable secondary sex characters are known for turtles. Special studies of the problem are being conducted.
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  • 42
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    Journal of Morphology 63 (1938), S. 345-361 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This species represents a typical example of protandric consecutive sexuality, the male phase becoming functional at a very early age, when the body has reached a length of only 3 to 7 mm. Those males which become functional earliest usually seek the association of older individuals in the female phase; others, maturing later, are more likely to remain solitary. Mated males have accentuated masculine characteristics and retain the male phase longer than solitary individuals or those that are isolated experimentally. Unfavorable environmental conditions postpone or prevent functional sexuality and terminate the male phase promptly without inaugurating the female phase. The influence of the female in accentuating the sexuality of the male is thought to be due to stimuli received by the latter through sense organs in tentacles and penis and mediated by the nervous system through hormonal secretions. Termination of the male phase and transition to the functional female are comparable to metamorphosis from the immature to the mature condition in other animals and, like metamorphosis, the primary (male) sexual phase can be abbreviated or prolonged experimentally, but the sequence cannot be reversed.
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  • 43
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    Notes: Data concerning the seasonal distribution of twenty-two species of nudibranchs are recorded for a period of 9 months. The occurrence of copulation and of egg laying for these animals in the laboratory aquaria is recorded for the same period. These data indicate that the seasonal distribution of certain species is well marked, and that there is in many cases a definite breeding season.The characteristics of the egg ribbons of these nudibranchs are described, and figured by means of photographs. These egg ribbons approach the mathematical form of a spiral of Archimedes. In every case observed, the ribbon was deposited in a counter-clockwise direction, viewed dorsally.The relationship between these observations and earlier work on the life histories of the nudibranchs is discussed.
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  • 44
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    Notes: Salivary gland nuclei in Chironomus regularly show large, conspicuous nucleoli. In Sciara no true nucleoli have been found, but sometimes certain particular chromosome regions expand greatly, forming ‘puffs’ or ‘bulbs,’ somewhat nucleolus-like in nature. Detailed study has been made of the chromosome structure in the affected regions in both genera.In the nucleolar regions of Chironomus the banded structure of the chromosome is distinctly modified. In the case of the large nucleolus the chromosome breaks up into a heavy network in which solid discs are replaced by interconnected chromatic spheres and granules, extending out somewhat into the clear nucleolar substance. In the case of the smaller nucleolus, Balbiani's ring, the banded structure is less disturbed. A chromatic network, resembling a system of rootlets, runs out from the chromatic bands into the clear nucleolar substance.In Sciara ocellaris the ‘puff’ regions are at times normally banded, but at other times in the condition described as ‘puffed.’ The same is true of the ‘bulb’ regions. The relation between nucleoli, puffs and bulbs is discussed. Also that between ‘heterochromatin’ and ‘euchromatin.’ Evidence seems to indicate that the latter are merely extremes in a continuous range involving different relative amounts of chromatic and achromatic materials. The ‘puff’ regions appear to be structurally similar to the chromocenter in Drosophila.
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  • 45
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  • 46
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    Journal of Morphology 63 (1938), S. 397-419 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The summary of this paper is as follows:1From an examination of 108 ovaries from eighty-nine individuals it was apparent that, in the cat a certain but variable amount of degeneration of primary follicles occurs in all life epochs.2The primary oocytes undergo the degeneration, while the follicle cells remain for an undetermined time.3The most profound instances of such degeneration were encountered in kittens of 6 to 9 weeks, accompanying or follwing the resolution of the egg cords into primary follicles and the establishment of the cortical or marginal zone. A sporadic degeneration of young oocytes occurs at earlier periods.4No evidence was seen of a new formation of egg cells from the residual follicle cells after the degeneration of the oocytes. The degenerations of the 6 to 9 weeks epoch are not believed to be of universal occurrence.5No adequate evidence was encountered of a new formation of egg cells from the surface epithelium, either before or after sexual maturity.6No evidence linking the degeneration of primary follicles with the estrous cycle was seen.7The stock of primary follicles established in the first few weeks after birth is believed to be adequate for the growth of graafian.
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  • 47
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    Journal of Morphology 63 (1938), S. 421-439 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The maturation of the germ cells of the two hermaphroditic species, Curtisia foremanii (Girard) and Bdelloura candida (Girard) has supplied the material for this chromosome study.Both species of flatworms are believed by the author to possess a diploid number of twelve chromosomes and a haploid number of six, although Curtisia foremanii has previously been reported as having a smaller and variable number of chromosomes.A tendency of the chromatids comprising individual chromosomes to separate from one another at certain times was noted in both species. This action results in giving the appearance of a larger number of chromosomes than the germ cells actually possess. A further source of apparent increase in chromosome number in the Curtisia oocytes, after treatment with the usual Allen's B3 and B15 and Heidenhain's iron haematoxylin, is the presence of some deeply staining, non-chromatin material.No significant differences in number, form and behavior of chromosomes of male and female complexes were noted, with the possible exception of the tendency of the chromatids to separate from one another, to be greater in the female than in male germ cells.
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  • 48
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    Journal of Morphology 63 (1938), S. 441-475 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Four cases of gynandry in American spiders present the following morphologic deviations: The specimen belonging to Neoantistea agilis (Keyserling) externally is a bilateral gynandromorph with distortion of the single male palp, with half of the epigynum nearly normal; internally both testes and ovaries are present. The Drassodes neglectus (Keyserling) is not a completely developed bilateral gynandromorph. One side has a normal male palp, a larger chelicera and longer legs than the other, the epigynum is complete and normal; internally only degenerate ovaries are present. The Linyphiid, near Bathyphantes, is three-quarters female, the only male organ being an imperfectly developed male palp. Ovaries are well developed but immature, whereas the epigynum is complete. In the Pardosa sternalis (Thorell) the anterior part of the body is male, as indicated by the swollen palps and the length of the legs; the epigynum is completely developed, but internal reproductive organs are missing except for a very much aborted ovary. The bisexuality in all cases has caused degeneration or abnormalities in the reproductive structures.Included is a tabulation of all recorded instances of gynandry in spiders, arranged according to the type of abnormality. The term ‘leg-index’ is introduced to express ratio between length of the leg and length of cephalothorax.
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  • 49
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    Notes: Centrifuging the eggs of Rana pipiens in the early gastrula stage prevents the formation of the hypophysis in some of the tadpoles. The absence of the melanophorotropic hormone normally secreted by the hypophysis seems to be responsible for the contraction of the pigment cells. In addition, there are actually fewer pigment cells present in both the dermal and epidermal layers of the light tadpoles than there are in the controls. The paleness, therefore, of the tadpoles seems to be due to both a contraction of the pigment cells present and to an actual reduction in their number. The failure of the hypophysis to develop was brought about by centrifuging at an earlier stage in development of the embryo than in previous extirpation studies. The effects produced by centrifuging that are responsible for the failure of the hypophysis to develop are unknown. However, it is suggested that interference in some way with the presumptive hypophysis-forming tissue has resulted in an inactivation of its inductive potencies.
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    Journal of Morphology 63 (1938), S. 491-529 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper is based on evidence obtained from sectioned skull of Galesaurus planiceps, Owen. Width-length index of skull is 67.7; height-width index 47.6. Dental formula is: \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{{\rm I\; 3\; or\; 4}}}{{{\rm I\; ?}}} $\end{document}, \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{{\rm C\; 1}}}{{{\rm C\; 1}}} $\end{document}, \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{{\rm PC\; 7}}}{{{\rm PC\; 9}}} $\end{document}. Length of prevomer is 24.0 mm., that of skull 62.0 mm. Maxilla contains cavity which appears to be equivalen of sinus maxillaris of mammals. Ear structure shows large internal auditory meatus. There is no evidence that horizontal and posterior semicircular canals pass through bone. Fenestra ovalis is large. Parasphenoid, basisphenoid, and basioccipital are fused. Parasphenoid consists of short body and a medial anterior process. Sella turcica lacks floor, probably due to erosion. Detached bone may be sphenethmoid. Dentary contains two canals, probably vascular. Comparisons with related forms lead to following conclusions: (1) Specimen is of young animal. (2) Dental succession of postcanines, distichical replacement of postcanines, long prevomer, short parasphenoid, incomplete osseous incasement of semicircular canals, and other characteristics label Galesaurus as primitive cynodont. (3) Reduction of parasphenoid and development of prevomer support Broom's view that Ictidosaurus is not a cynodont. (4) Prevomer as nasal septum; fusion of parasphenoid, basisphenoid, and basioccipital; large lacrimal, splenial, and articular; and other characteristics indicate that Galesaurus is off line leading to mammals. (5) In certain respects cynodonts are more mammal-like than gorgonopsians.
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  • 51
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: The development of the cranial musculature of Amblystoma punctatum is described in detail, for both larva and adult. In addition, a brief account of the innervation of each muscle is given. The study of normal development is supplemented by extirpation experiments performed on embryos in early stages of development. These extirpations include the mesodermal head segments, mesoderm of mandibular, hyoid, second branchial, third branchial arches, and somites 1, 2 and 3. The eye muscles are found to develop from the mesodermal head segments in precisely the same manner as in other classes of vertebrates; head segmentation of Amphibia, though less accentuated, is shown to be homologous with that of other classes. The remaining extirpation experiments corroborate, in general, the finding from normal development studies. An attempt is made to summarize in tabular form the prospective fate of the prechordal plate and parachordal mesoderm, the two earliest divisions of the head mesoderm, with regard to their complete muscle derivatives.
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  • 52
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    Journal of Morphology 57 (1935), S. 275-302 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sexual dimorphism of Chinese cobitids consists of peculiar structures of the pectoral fins and of variations in the lengths of these as well as of the ventral fins. In all groups the paired fins are, as a rule, longer in the male sex, and the female has no lamina circularis, enlargement of pectoral rays or dilation of lateral muscles.In males of Cobitis and Misgurnus, the second rays of the pectorals are enlarged and possess at their base a bony plate (lamina circularis). In other Chinese genera the lamina circularis is absent. Males of the Misgurnus group are easily recognized by the dilation of the lateral muscles in the region of the dorsal fin. Males of Barbatula have several enlarged inner rays in the pectoral fin and numerous nuptial tubercles on the head, arranged in prepercular and preorbital groups. In the European, B. barbatula, however, tubercles on the head are wanting.In males of the Leptobotia and probably Botia groups, the first pectoral ray is enlarged, and the membrane between several of the inner rays is covered with nuptial tubercles.In general, in the Chinese cobitids the differences in sexual dimorphism are correlated with the differences between genera, i.e., each genus possesses a quite different sexual dimorphism; thus the secondary sexual characters can be used for taxonomic purposes.
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  • 53
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    Journal of Morphology 57 (1935), S. 533-545 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The thyroid primordium is a solid median outgrowth from the pharynx which is attached to the truncus arteriosus at its bifuracation. The thyroid is soon detached from the pharynx and migrates to its definitive position ventral to the aorta between the bases of the third visceral pouches. After detachment the primary follicle appears in the lower part of the primordium; during migration and early growth it is divided apparently by stress and pressure to form secondary follicles. Independent follicles are formed also by secretion of colloid between solid masses of thyroid cells. Other secondary follicles are formed by pinching off evaginations from large follicles. Colloid appears soon after the primary follicle is divided. The adult thyroid is a group of follicles scatterd in a venous plexus in the ventral pharyngeal region, around the aorta.
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  • 54
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    Journal of Morphology 57 (1935), S. 617-653 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Three to 5 minutes after implantation of a spermatophore in Placobdella parasitica there is a pronounced granulation of the tissues in the immediate region of the capsule. During the following 20 minutes a path 81 to 120 μ across communicating with the sinuses of the body cavity is established. By a mechanical shrinkage of the distended spermatophore the spermatozoa are injected through this path into the coelomic sinuses. They are dispersed through the body by the haemolymph and possibly by muscular contractions of the recipient. Fifty to 75 hours after their introduction into the body some of them arrive in the ventral sinus. From here they penetrate the walls of the ovisacs and take up a position in the lumina in preparation for fertilization. Two to 30 hours after implantation a plug of cells composed of migrating cellular elements of the recipient's body and of cells introduced along with the spermatozoan bundles forms in the subhypodermal region of the sperm path. Twenty to 45 hours later the wound is entirely repaired. Hypodermal epithelium is replaced by a migration into the affected region of similar reserve cells. The parenchymatous tissue is restored by a differentiation and growth of some of the cellular elements making up the plug.
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  • 55
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    Journal of Morphology 58 (1935), S. 1-39 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Flatfishes lying on one side and that blind and colorless, but having the upper side two-eyed and colored are abnormal fishes which in their own group are perfectly normal. Some normally lie right side up (dextral) others point left (sinistral). Any departure from these normal conditions constitutes such a specimen an abnormal flatfish. The simplest departure is reversal-i.e., a normal dextral fish lies on its right side and points left and vice-versa. Sixteen reversed fishes have been described, but in various species from 3 to 100 per cent reversals have been noted.Reversal might be thought dependent on the structure of the optic chiasma. The Psettodidae (lowest family) have a dimorphic chiasma (right or left nerve dorsal) and are indifferently dextral or sinistral. But the dextral Soleidae and the sinistral Cynoglossidae (highest families) have dimorphic chiasmas with only five recorded reversals. In between, the monomorphic sinistral Bothidae have the right nerve dorsal even in the five indifferent species. And the monomorphic dextral Pleuronectidae include three indifferent species (one having up to 100 per cent reversed) with the left nerve dorsal even in reversed fish. The explanation of reversal must be found in genetics.
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  • 56
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    Journal of Morphology 58 (1935), S. 157-172 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study reveals the existence of four distinct but genetically related types of upper jaw mechanisms:1. The non-protractile, with no mechanism for the protrusion of the pre-maxillae. The maxillaries form part of the upper margin of the mouth, as in Isospondyli, Apodes and Haplomi.2. The crossed ligaments in the snout as in Acanthopteri, Heterosomata and Anacanthini.3. The twisting action type in which the internal hook of the maxilla drives out the pre-maxilla as found in Cyprinodontes and Percesoces.4. The rostral or sigmoid ligament attached to the pre-maxilla as in Cyprinidae and Catostomidae.The three protractile types all possess an enlarged pre-maxilla with a medium dorsal process, suggesting a common origin of all from a single non-protractile form of upper jaw.
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  • 57
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    Journal of Morphology 58 (1935), S. 211-220 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The shell of Cardium corbis is composed of three layers, an outer periostracum of conchyolin and two layers of aragonite. The outer aragonitic layer presents a laminated appearance, but in reality is made up of fibers which extend across several of the curved lamellar lines. Each fiber is enclosed in an organic sheath which can be dissolved in potassium hydroxide. The inner aragonitic layer is composed of vertical prisms which are made up of two sets of fibers inclined to each other at an angle of 55 to 60°. The outer layer of aragonite is secreted by glands on the mantle edge outside the pallial line; the inner layer is secreted by glands on the mantle area within the pallial line. The dentition is formed of the same material as the inner aragonitic layer.The ligament is composed of two layers, the outer being less impregnated with calcium carbonate than the inner. Both layers are continuous with the organic matrix of the shell.
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  • 58
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    Journal of Morphology 58 (1935) 
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  • 59
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    Journal of Morphology 58 (1935), S. 355-383 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: New dissections of the caudal and short posterior thigh muscles of the reptiles Iguana, Varanus, Crocodilus and Testudo, and the mammals Sciurus, Galago and Herpestes were made, and the findings correlated with those described in the literature. The condition in the lizards, Sphenodon and crocodiles is very constant; in each case there is a puboischiofemoralis externus and an ischiotrochantericus passing from the pelvis to the femur, a deep caudal mass passing from the tail to the femur, and a superficial caudal sheet attached to the ilium and ischium. In the Chelonia, with the specialization of the gait, the deep caudal musculature has lost its attachment to the femur, and has migrated onto the vertebral column and the inner surface of the pelvis, while the other muscles occupy their typical position. In the Mammalia the deep caudal musculature has undergone a change similar to that in the Chelonia, forming the pubo-, ilio-, sacro- and ischiococcygeus muscles, while the superficial caudal musculature has disappeared except for a part which forms a sphincter cloacae. The posterior part of the puboischiofemoralis externus has formed the quadratus femoris, and the ischiotrochantericus the obturator internus and the two gemelli. In specialized mammals with reduced tails the caudal musculature has taken over new functions and become respecialized in different ways.
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  • 60
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    Journal of Morphology 58 (1935), S. 419-437 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: A histological study has been made of the developing mid-gut or mesenteron of Melanoplus differentialis from diapause until after hatching. The primitive mid-gut consists at first of a single laver os squamous epithelium surrounding the yolk; to this is added later an outer layer. These two layers give rise to the muscular and connective tissue elements of the definitivo mid-gut. Near the of hateching, vitellophanges which have been present in the yolk since earlier stages migrate peripherally to form a lining upon the inner surface of the primitive mid-gut. The vitellophage nuclei divide to form the smaller nuclei of the definitive epithelium of the mid-gut. The vitellophage nuclei divede to form the smaller nuclei of the definitive epithelium of the mid-gut. The development of the definitive mesenteron fron the primitive mid-gut takes place rapidly and occurs near the time of hatching.
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  • 61
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    Journal of Morphology 62 (1938) 
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  • 62
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    Journal of Morphology 62 (1938), S. 3-15 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Comparisons have been made of the weights of the suprarenals of 525 mature female dogs in dioestrus, oestrus, pregnancy and lactation. Tables and graphs show that there was a slight increase in the size of the suprarenals during oestrus. There was hypertrophy of both the cortex and the medulla in the oestrous dogs. Only slight increase was shown in the weights of the glands of pregnant animals when the net body weight was considered and no increase when the total body weight was used in the study. There was no hypertrophy of the glands of lactating animals.There was only a slight variation in the seasonal occurrence of oestrus. From 34 to 37% of the total numbers of mature females examined in the seasons were found to be in oestrus. From 13 to 16% of the total numbers were found to be pregnant.
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  • 63
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    Notes: Nucleoli in the germ cells of certain Orthoptera, Hemiptera and the crayfish have been studied. In Ceuthophilus (camel cricket) these bodies are found to be definitely connected with chromatin threads and are believed to be products of chromatin.The large structure in the ova of Nemobius (cricket) is interpreted as a nucleolus because of its very irregular behavior and apparent complete disappearance.It is found that some of the nucleoli of Gelastocoris (toad bug) arise within the chromatin threads.Observations on Cambarus (crayfish) fail to show nucleolar extrusion, a phenomenon which has formerly been reported for this form.The unique behavior and fate of the nucleolar material in Pselliopus (true bug) is described. In this species the nucleolar material is added to and becomes part of the general oxychromatin network of the nucleus.This study fully supports the opinion that nucleoli have a chromatin origin.
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  • 64
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: A new limb skeleton will form in regenerating limbs of the larval Amblystoma in which the humerus had been completely removed. The cartilage of the new limb skeleton develops out of a blastema in which there are no cells of cartilage origin. This regeneration blastema is a composite structure made up of cells derived from a dedifferentiation of the injured tissues of the limb. The tissues which have been observed as contributing to the regeneration blastema are: muscles, especially the muscles of the shoulder; connective tissue of the sheath of the brachial nerve plexus; muscle connective tissue; and, to a certain extent, subcutaneous connective tissue. The new cartilage of the limb skeleton develops out of this composite blastema by means of a differentiation of cells in the central axis of the blastema.The amount of cartilage regenerated appears to depend on the mass of the blastema. When the blastema does not extend fully into the glenoid cavity of the scapula, the head of the developing humerus is deficient in size and structure. However, a complete limb skeleton is regenerated when the blastema does extend fully into the glenoid cavity.Since the new cartilage of the regenerated limb has no genetic continuity with the old limb skeleton, it would appear that the limb field exerts some kind of histogenetic determining action.
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  • 65
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    Journal of Morphology 62 (1938), S. 263-297 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Artemia salina, a very widely distributed species in North America, Europe and Asia, breeds freely and rapidly under laboratory conditions, living in all salinities from fresh water to almost saturated brine. Its soft exoskeleton permits of easy sectioning.The morphology and embryology of the segmentally arranged excretory glands - the antennal, mandibular and maxillary glands, are described. The antennal gland, consisting of extracellular end sac and intracellular excretory duct, is located in the second antenna and opens to the exterior on the lateroposterior face of the protopodite. It attains its maximum development by the sixth instar, degenerating by the tenth. The vestigial mandibular gland consists only of an end sac surrounding a schizocoele, and a rudimentary duct. The large maxillary gland in the adult consists of an end sac, an excretory duct of three circular coils, and a terminal duct opening to the exterior. The maxillary gland develops from a mass of mesenchyme cells in the maxillary segment of the nauplius, becoming fully differentiated by the sixth instar.The vestigial second maxilla has two bristles. It serves only as a terminus for the maxillary gland. A pair of small ganglia are accepted as internal evidence for the presence of a maxillular segment.The presence of three pair of schizocoeles in three consecutive segments is interpreted as evidence of homology with the Annelid coelome, with the possibility of further homologizing the excretory ducts with the segmental nephridia.
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    Journal of Morphology 62 (1938), S. 503-521 
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    Notes: In early embryonic stages of Passalus there are, in addition to the brain and suboesophageal ganglion, three thoracic and ten abdominal ganglia; one ganglion to each body segment. Before hatching the tenth, ninth and eighth abdominal ganglia coalesce. During the three larval instars the terminal ganglion remains in the sixth abdominal segment and only minor changes occur. By the end of the third day of pupal life the adult form of the nervous system is practically assumed. All abdominal ganglia are fused into a single, solid, elongated ganglionic mass. Connectives have disappeared between meso- and meta-thoracic and between metathoracic and abdominal ganglia; and with exception of the brain, sub-oesophageal and prothoracic ganglia, the entire ventral chain has come to lie in the mesothorax. The peripheral nerves still arise from the ganglia and ganglionic mass in their same relative positions and still supply the same segments in which they were originally located.
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  • 67
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    Journal of Morphology 62 (1938), S. 599-607 
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    Topics: Biology , Medicine
    Notes: Analysis of measurements of the trunk region of the vertebral column and of the various segments of the wing and leg skeleton in sixty-four specimens (thirty-four males, thirty females) of Fulica americana shows that: The males average about 7% larger (longer) than females in all parts of the skeleton; the difference is uniform throughout the body. The coefficient of variability ranges from about 3.00 (humerus, et al.) to about 5.00 (hind toe). The correlation between lengths of parts is very high between different segments of the wing skeleton, or of the leg; it is somewhat less between homologous segments of the wing and leg; and it is still less between limbs and trunk. This decreasing order of correlation indicates an increasing order of independence of variability. The wing proportions in Fulica are those characteristic of the type of flight called flatterflug. The proportions of the leg are those of a bird moderately adapted for cursorial locomotion; the very long toes characterize a swimming bird.
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  • 68
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    Journal of Morphology 57 (1935) 
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  • 69
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    Journal of Morphology 57 (1935), S. 31-59 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The little capsules in which snails of this family deposit eggs are so durable as sometimes to be found adherent to museum specimens; hitherto, however, detailed descriptions of such capsules have been restricted to the capsules long known as made by Neritina fluviatilis in fresh waters of Europe. The present paper adds descriptions, with measurements and sketches, of Neritina reclivata from Florida, Neritina virginea, Neritina punctulata, Theodoxus mneleagris, Nerita peloronta, Nerita alticola, Nerita tesselata and Neritilia succinea from Jamaica, British West Indies.These capsules are found to be remarkable in that the digestive tract aids in their formation; that is, the capsules are made as secretions of the lower oviduct to which mineral particles are added, and these mineral particles are supplied from the intestine and stored up in a special sac opening into the oviduct. Moreover, the mineral particles are of twofold origin; in some Neritinas they come from the ooze taken in with the food and passed through the intestine; in some Neritas they come from the liver as calcospherites, to be passed through the intestine.It is hoped that the data given will aid future descriptions of capsules from other species till a firm foundation is built for utilization of these capsules as aids in taxonomy.
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    Journal of Morphology 57 (1935), S. 105-112 
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    Notes: There is as yet no proof that the prepollex and postminimus ever occurred as actual digits. Romer's discovery of previous confusion of the preaxial with the postaxial fin border of Sauripterus allows a more accurate interpretation of primitive conditions. The latter involved essential asymmetry. The carpal cartilages of the Sauripterus type offin must have split into transverse rows. When the radius and ulna had become of equal length there was redistribution of the most proximal carpals, thus displacing elements in the other rows. It seems that eventually the original first carpale assumed the position and function of a first metacarpal, while the original fifth metacarpale assumed the position and function of a fifth carpale.
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    Journal of Morphology 57 (1935), S. 113-129 
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    Notes: The external genitalia of female termites are readily homologized with those of female roaches. Mastotermes and other representative termites from every family are compared and their phylogenetic relationships within the group are found to agree, with the exception of the Hodotermitidae, with those based on studies of other structures.
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  • 72
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    Journal of Morphology 57 (1935), S. 131-145 
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    Notes: A hitherto unknown secondary sex character in male frogs consists of a series of connective tissue bands which extends the entire length of both layers of the Obliquus muscle, at both their dorsal and ventral borders. Extensions of the ventral bands may be carried inward toward the midline at certain of the inscriptiones tendinae. These bands are named the Lineae masculinae. They are clearly visible in specimens from which the skin has been removed, and are visible even through the skin in living specimens of certain species of Kaloula.Ninety-one genera and 553 species of the frogs and toads of the world were examined for the presence or absence of this structure. It is distinct in the common American and European ranids, such as Rana pipiens and Rana esculenta. It is entirely absent in many genera. When present it is found only in adult males, being absent in sexually immature males and females of all ages. Examination revealed no seasonal variations in males of Rana pipiens. This indicates that there is some correlation between the expression of this character and the sexual hormones. No function is assigned to the Linea masculina, although it is suggested that it may be associated in some way with voice production. A discussion of the taxonomic distribution of the character is included.
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    Journal of Morphology 57 (1935), S. 213-251 
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The hyobranchial apparatus and throat musculature of the plethodontid salamanders are examined. The interhyoideus is thought to be the homologue of the intermandibularis posterior and the posterior part of the intermandibularis anterior. The quadrato-pectoralis is found only in Desmognathus (Leurognathus?), and Aneides. Its presence in the former is a primitive condition; in the latter, secondary. The gularis had its phylogenetical origin as a slip from the quadrato-pectoralis. The lingual cartilage is found only in Gyrinophilus, Pseudotriton, Eurycea, and Manculus. It is the homologue of the [sehnenplatte] of Salamandra; not the otoglossal. The presence of the suprapeduncularis and the absence of the genioglossus is not peculiar to adult free tongued genera. The anatomical evidence allies Batrachoseps with Hydromantes and Oedipus. The latter two genera are derived from ancient Plethodon stock, not from Gyrinophilus stock. Stereochilus, Typhlotriton, and Typholomolge are the degenerate descendants from ancient Gyrinophilus stock.
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    Journal of Morphology 57 (1935), S. 429-459 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Accounts of binary fission for two species of Chilomastix by Bélar ('21) and Boeck and Tanable ('26) differ. Consequently, investigations were initiated to study the cytology and to determine the nature of binary filssion in Chilomastix mesnili of man, Chilomastix mesnili (?) of anthropoid apes and monkeys, and Chilomastix intestinalis of guinea pigs.The material used for the study included the following: four heavily infected human cases of Chilomastix mesnili, twenty-one infections of Chilomastix mesnili (?) from a survey of thirty-six anthropoid apes and monkeys at the Philadelphia Zoölogical Gardens, and Chilomastix intestinalis from six guinea pigs.The results of the investigations indicate that binary fission of the above three species of Chilomastix are similar in essential details. Encystment is described for the species from man and from anthropoid apes and monkeys. No evidence for mitosis within the cysts was obtained for C. mesnili of man. In C. mesnili (?) from primates other than man, the appearance of cyst nuclei resembling mitotic processes is explained as variations occurring in nuclei. Binucleate cysts are believed to be formed by the encystment of abnormal binucleate individuals which never had undergone plasmotomy after division of the nuclei.
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  • 75
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Studies of regeneration in a denuded area 3 to 5 mm. square made by dissecting away the epidermis and underlying dermis were carried out both in the living animal and with the aid of histological sections. During the reconstitution of the area pigmented cells appeared in the new epidermis. There was no evidence that they wandered in from the surrounding epidermis. They developed in situ and most of them later disappeared. In the deeper tissues of the regenerating area, pigmented cells appeared in localized areas which gradually increased in size and density of color and formed typical black spots. These remained permanently.If the incision passed through or close to an original spot there was migration of melanophores into the adjacent territory and the subsequent formation of a spot. All other new spots were formed from melanophores which appeared in situ, by the formation of pigment in cells which had previously been unpigmented.
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  • 76
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    Journal of Morphology 58 (1935), S. 573-583 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The number and behavior of the chromosomes have been investigated in the spermatogenesis of Cryptobranchus allegheniensis. The spermatogonium contains sixty-two chromosomes, which are composed of twelve atelomitic V-shaped ones, and eighteen long and thirty-two short telomitic ones. The haploid number of chromosomes is ascertained to be thirty-one in both of the primary and secondary spermatocytes.The chromosomal relation between the present species and Megalobatrachus japonicus, a closely related form, has been discussed.
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  • 77
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    Journal of Morphology 58 (1935), S. 585-613 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: 1. The developing chick thyroid consists of epithelial plates or cords suspended in a sinus, probably lymphoid. These cords in cross section have the appearance of follicles.2. Growth in size is accomplished by fusion of follicles. Growth in number of the latter by proliferation of inter-follicular epithelial cells.3. Colloid first appears on the tenth day of incubation. The tadpole test indicates the beginning of functional activity at this time.4. During development there is a progressive decrease in the cytoplasm-nucleus ratio from 3.3: 1 on the third to 1.5: 1 on the nineteenth day, as measured in area, not volume.5. Not only is chromophobe and chromophile colloid present in different cells of the same follicle at the same time, but both are occasionally present in the same cell at the same time.6. Evidence of heightened activity in the chick thyroid are as Uhlenhuth (′28) describes them in salamanders: namely, high columnar cells, apically located secretion granules, and vacuoles of chromophobe colloid.7. Follicles in late developmental stages have, at some time during their functional cycles, tubular exits, which are thought to represent one path through which colloid reaches the circulatory spaces.8. Vital staining indicates that elements of the reticulo-endothelial system are present in the developing thyroid. Phagocytic cells in the gland of one embryo were observed phagocytosing entire erythrocytes.
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  • 78
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    Journal of Morphology 57 (1935), S. 353-427 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In ascidians the development of eggs and of buds are in sharp contrast. In bud development cell sizes are minimal throughout. Gross differentiation of form becomes apparent from the beginning, histological differentiation only when cell division is ending. The position of a cell relative to the whole determines its nature. Multiplication of cells continues until sufficient have been formed for the expression of all specific and other characters. In sexual development the egg is a large cell which divides until the minimal cell sizes characteristic of the species are obtained. The course of cleavage is a curve suggesting the attainment of a state of equlibrium. Commencing before fertilization and continuing during cleavage is a precocious differentiation of certain parts that inhibits further cell division and results in the formation of special larval structures that function when a mere fraction of the whole developmental period has elapsed. This differentiation may be suppressed, or may be retarded, without affecting the development of the rest of the egg. In the remaining parts cell division continues until minimal cell sizes are reached and only then does histological differentiation become apparent, as in asexual development. The number of cells thus formed is very small compared with that necessary for the expression of the full character of the species, and the newly functional postlarval organism is necessarily peculiar in structure.
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  • 79
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Cyto-centrosomes containing centrioles but lacking asters originate de novo in great number throughout the ooplasm of Habrobracon eggs during the formation of the first maturation metaphase. These cyto-centrosomes apparently arise from accessory nuclei which are formed from granules extruded by the germinal vesicle. The accessory nuclei react negatively to the Feulgen nucleal test.Asters similar to those present in artificially parthenogenetic eggs appear around many of the cyto-centrosomes, thus forming cytasters. These are manifest only after the female pronucleus establishes an association with a cyto-centrosome, which thus becomes the nuclear centrosome.In the parthenogenetic egg the centriole of the nuclear centrosome is continuous from one cell generation to the next, whereas the centrioles of the cyto-centrosomes which are unassociated with nuclear material are not perpetuated and disappear during early cleavage.Concerning the origin of the first cleavage centrioles in fertilized eggs, evidence shows that in some ova it is entirely maternal, that is, from two cyto-centrosomes, one associated with the female pronucleus and occupying one pole of the first mitotic spindle, and the other associated with the male pronucleus and located at the opposite pole; while in other ova it is maternal-paternal; from two centrosomes, one the sperm centrosome which occupies one pole of the first cleavage spindle, and the other a cyto-centrosome associated with the female pronucleus and situated at the opposite pole.
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  • 80
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    Journal of Morphology 62 (1938), S. 243-261 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Collections of Campeloma rufum were made at all seasons of the year from the Salt Fork River at Homer Park, Illinois, for gross anatomical and histological studies. No males nor male reproductive cells were found, all individuals showing definite female structures. The gonad, found on the columellar surface of the digestive gland, shows ovarian cells. A U-shaped tube from the albumen gland to the uterus receives the oviduct near its proximal end. This duct leads into a glandular pocket, the shell gland, which in turn empties into the sac-like uterus. The uterus terminates near the edge of the mantle in a muscular vaginal tube. The previously undescribed kidney, a glandular, pyramidal organ, lies posterior and to the left of the upper end of the mantle cavity. The kidney possesses two orifices opening into the pericardium and ureter respectively. The ureter opens between the vagina and the anus. Intra-uterine young were observed during all seasons of the year varying progressively from small veliger to fully formed young. A later paper on oogenesis, will attempt to substantiate parthenogentic reproduction for C. rufum.
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  • 81
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: A detailed study of Wright's polydactylous monster (produced by a semi-dominant lethal gene) indicates that it belongs to a general type found also in rare human cases. The diagnostic characteristics are: clubbed feet and approximately double the usual number of digits, embryonic posture, microphthalmia and enlargement of the diencephalon, and missing tibia and telescoped sternum; all organ systems in the body except the genital and circulatory are grossly abnormal. The defects appear to be produced by an arrest of morphogenesis and an alteration of relative growth rates. It is indicated that a controlling center of digit formation exists on the lateral (postaxial) side of the foot, that skeletal and dermal structures are controlled by it, but that muscles are differentiated according to the area of the limb in which they lie. The gene itself is not atavistic, although its effects in the heterozygote have that appearance.
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  • 82
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    Journal of Morphology 62 (1938), S. 393-413 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The microscopical examination of the first haploid salamander to live through metamorphosis shows that the transformation to a terrestrial vertebrate was normal and practically completed at the time of its death. All the organs and structures that develop shortly before and during metamorphosis and are typical for the adult salamander, e.g., the integument, the pharyngeal derivatives, and various glands of special function, are present.The nuclei in all organs and tissues of the haploid animal are smaller than normal. This is indirect evidence of the uniformly haploid condition of the animal. The majority of the organs are smaller than in the control but contain a larger number of cells. In some glands, the reduced cell size has been completely compensated by the increase in cell number.
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  • 83
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    Journal of Morphology 62 (1938), S. 375-391 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study is made of the pancreatic islands in Rana clamitans, R. catesbiana, R. sylvatica and Hyla versicolor during various stages of development. The islands, which were first seen in the 8-mm. R. clamitans larvae, originate from the endodermal cells of the primitive pancreatic anlagen. Following early larval development in all of the species, new islands differentiate from the cells of the pancreatic ductules. During metamorphosis, much of the acinous tissue degenerates, but the islands persist. They become aggregated and the definitive islands are formed from the primary islands before the mature adult stage is reached.With the azure-eosin technique, two types of island cells were distinguishable before, or at the time of metamorphosis, in all of the anurans studied. They are designated as the red and blue types. The blue cells are considered the primitive or embryonic type, and may transform into the red type; or the red type may originate independently.
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  • 84
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    Journal of Morphology 62 (1938), S. 523-557 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ovaries of bats, Myotis lucifugus lucifugus and M. grisescens, have been studied in all phases, except gestation, of the annual reproductive cycle. Oocytes arise in the germinal epithelium and grow with an orderly differentiation of the storage products of metabolism - chondriosomes, fat drops, and yolk vesicles. The evidence indicates that the zona pellucida is derived from the oocyte. Squamous cells of the primary follicle become cuboidal and then columnar as follicular growth begins (unilaminar secondary stage). The secondary follicle becomes multilaminar and in a very few cases gives rise to a tertiary follicle by antrum formation. Most growing follicles undergo retrogression by one of two methods. Degeneration of type I is common in multilaminar follicles and begins in the granulosa which is almost completely obliterated before the oocyte is affected. Spindles occur in some of these oocytes and fragmentation is common; phagocytes eliminate the contents of the zona. In type II, which is rare and has been found only in unilaminar secondary follicles, the oocyte degenerates, leaving an uninjured granulosa. Medullary cords are common embryonic vestiges in these ovaries; epithelial nodules are less frequent. Interstitial cells are very numerous in newborn bats, arise throughout life from the hypertrophied thecae internae of retrogressing follicles of type I, are phagocytized and, also, undergo hyaline degeneration, are hypertrophied in late pregnancy, and continue so during lactation.
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  • 85
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    Notes: Separation of the mantle from the visceral mass on the right side in deeply cupped species of oyster provides a shorter channel for egress of water from the right demibranchs. Correlated with this change is reduction in size of the right epibranchial chamber beneath the adductor together with backward displacement of the adductor itself. This water passage, designated the promyal chamber, develops during the first week after attachment of the oyster larva. The greatest displacement of the adductor and the largest promyal chamber occur in O. frons. The mantle border shows three reduplications of which the innermost, the pallial curtain, controls the amount and the place of entrance and egress of water. The importance of pallial curtains and promyal chamber to survival in turbid waters is discussed; oysters with the promyal chamber have invaded the river mouths, the flat oysters without this chamber have remained in the clear waters of high salinity near the sea. The bearing of these factors on the disappearance of fossil oysters is considered. It is proposed to relate to the genus Ostrea all flat, larviparous oysters which lack the promyal chamber and to raise the subgenus Gryphaea to generic rank to include all deeply cupped oviparous oysters with the promyal chamber. Anatomical and histological features of the pallium and branchial chambers are considered in detail.
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  • 86
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    Journal of Morphology 57 (1935), S. 169-183 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 87
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    Journal of Morphology 57 (1935), S. 91-104 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Chlamydoselachus anguineus has, extending across the upper front mouth just behind the origin of the rear teeth of each row, a shelf of tissue forming a functional breathing valve. Valves of three types were found in five specimens. One has the hinder edge crescentic, another is like the head of a ‘broad arrow,’ and the third is intermediate in outline. A similar valve, crescentic in outline has been found in the upper front mouth of a 13-foot specimen of Cetorhinus maximus dissected in the American Museum.Breathing valves are briefly described in thirteen marine teleosts at Tortugas, Florida. Some fishes had only maxillary valves, some mandibular, and a few had both. These consist of thin folds of tissue which swing back and forth as the fish breathes. A brief summary is given of breathing valves in other teleosts and in sharks and rays.The function of breathing valves in fishes is to prevent regurgitation of water during expiration as the fish swims along with partly open mouth. It is also correlated with feeding where the food is impaled on the teeth and held for swallowing, or where the fish feeds on pelagic organisms collected by swimming along with open mouth.
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  • 88
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    Journal of Morphology 57 (1935), S. 147-167 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytoplasmic structures in the spermioteleosis of Bruchus quadrimaculatus were studied, using various fixatives and stains including vital and smear techniques.Mitochondria appear in all stages following spermatogonia, exhibiting characteristic appearances during mitoses and in the spermatids. The [central substance] in the halves of the nebenkern becomes localized along the edges of the outgrowing [ribbons] as the source of the marginal filament. The undulating membrane apparently is formed by the fusion of these [ribbons.] The axial filament arises from the distal centriole, being permanently attached thereto, and lies along one edge of the undulating membrane of the tail.Golgi bodies are first observed in the secondary spermatocyte; they behave characteristically during spermiogenesis, producing the acrosome and leaving a residuum, the Golgi remnant, to be sloughed off with the cytoplasm from the tail.Chromatoid bodies occur in some spermatids but not in others. They migrate backward along the axial filament to be rejected with the Golgi remnant.
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  • 89
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 90
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    Journal of Morphology 57 (1935), S. 303-316 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The left side of the coelom of the fish is occupied by the large liver and the right side by the remaining digestive organs. The alimentary tract makes one complete coil upon itself in the coelom and terminates in an anus behind the ventral fin. The spleen is in a position dorsolateral to the liver, and its typical histological structure is modified by the presence of pancreatic tissue. The pancreas is scattered through the mesenteries of the organs in this region.The swim bladder is dorsal to the visceral organs and outside of the abdominal peritoneum. It is extensively bifurcated in the male, but only slightly bifurcated in the female.The two kidneys lie posterior to the gills and ventral to the spinal column. Two wolffian ducts arise from their posterior ends and extend posteriorly, uniting near the end of the coelom to form one duct which extends to the urinary bladder which opens into the urogenital sinus.The gonads are posterior to the anterior portion of the digestive tract. Posteriorly, the gonads open into the urogenital sinus which opens anterior to the anal fin.The anatomy of the circulatory system is unusual in that the dorsal aorta is situated on the left side of the spinal column. The right posterior cardinal vein remains as the continuation of the caudal vein.
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  • 91
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    Journal of Morphology 57 (1935), S. 317-333 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The pigmentary system of Palaemonetes vulgaris contains four pigments. These are red, yellow, blue, and white. With the exception of the blue all are found exclusively within chromatophores and are capable of becoming either dispersed into chromatophore branches or concentrated into chromatophore centers. The state of dispersion or concentration of each pigment is quite independent of the state of any other pigment and is determined by the color of the background upon which the animal lies. It is by the mixing of appropriately colored pigments by dispersion of those pigments that the animal adapts itself to its background. The blue pigment appears to be in the same chromatophore with the red but its dispersal is not restricted by the confines of the pigment cells, and its disappearance from tissues seems to be a case of destruction in situ. The rates of measured in background changes. In the case of each pigment, concentration was more rapid than dispersion and the rates for the red and white pigments were approximately the same.
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  • 92
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    Journal of Morphology 58 (1935), S. 189-209 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Although there has been much dispute in the past concerning the structure and function of the slit sense organs it is highly probable that they are chemoreceptors somewhat analogous to the pore-plate organs on the antennae of insects. The cuticular portion of a compound organ is made up of a number of more or less parallel slits in the outer cuticula. These slits are separated by thick laminae arranged as in a grid. A thin epicuticular membrane covers both laminae and slits between, while a thinner membrane is present at the inner ends of the slits. The hypodermal portion is composed of tall cells with a granular basal and a fibrillar distal cytoplasm. The sense cells are typical bipolar neurones, one for each slit of the organ. The distal sensory fiber traverses the fluid filled slit and ends at the epicuticula. It is never exposed directly to the outside. The structure of single slits is essentially similar to that of compound organs. In accordance with Schenk's well-known system of nomenclature for analogous structures in insects the term sensilla tomosa is suggested for both. The results of this study in fifteen species from nine families indicate that these organs are the same in all spiders, and that they are adapted for the function of chemoperception.
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  • 93
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    Journal of Morphology 58 (1935), S. 221-256 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In a paper published by the author in 1931 there was described a process of cell division called ‘modified mitosis.’ The present report adds quantitative studies of the process and a general evaluation of it and its role in the development of the embryo. Cell counts were made in various stages of chick embryos and the mitotic indices determined. In no cases can these mitotic indices account for the growth which the cell counts indicate. Periodicity in cell division in the chick cannot be established. Modified mitosis appears after careful study to be fundamentally mitotic in nature. Actual division of chromatin, nucleus, and cytoplasm occurs. Modified mitosis is not amitotic in character, but it is probable that it is what has been reported in the past as amitosis. It is very doubtful whether amitosis is found in the chick or in any of the vertebrates. Modified mitosis is part of the active phase of cell division and cannot be explained away as merely resting stages containing one or two nucleoli. It is probable that the division of chromatin nucleoli cannot be accounted for on any other basis than that of modified mitosis. In modified mitosis we undoubtedly see irreversible cell differentiation. The genetic implications of this process are not yet clear. If present interpretations of modified mitosis are in error a complete revision of our ideas of typical mitosis is in order.
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  • 94
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    Journal of Morphology 58 (1935), S. 257-277 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The neuromotor system and associated organelles of Oxytricha have been studied in living specimens viewed with dark field illumination, and in whole mounts and sections stained with Heidenhain's hematoxylin or Mallory's stain. Microdissection has also been used in some cases.The neuromotor system has been found to consist of the adoral membranelles and coordinating fibrils, the undulating membrane and its basal fibril, two sets of cytostomal fibrils and two sets of postesophageal fibrils. The anal cirri may possibly be involved in the complex. No neuromotorium seems to be present.Motor and feeding organelles not morphologically connected with the above system are eight frontal and five ventral cirri, and a varying number of marginal cirri. The anal cirri, if not connected with the neuromotor system, would be included here. The minute structure of each type of cirrus has been studied, and the action and probable function has been determined from studies on normal, anesthetized, and dissected individuals. A brief comparison is made between the neuromotor system and organelles of Oxytricha and those of Euplotes and Paramecium that have previously been described in the literature.
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  • 95
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    Journal of Morphology 58 (1935), S. 285-353 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The larval epithelium cells of Mycale syrinx (O. Schm.) unite syncytially with one another. The stratum so formed is continuous with the syncytial interior of the larva and into this interior the epithelial nuclei are drawn. Many of them degenerate and are digested by the syncytium or, eventually, by nucleolate cells. The syncytial cytoplasm breaks up into cell bodies, some surrounding epithelial nuclei and thus forming choanocytes, others surrounding nucleolate and non-nucleolate mesenchyme nuclei. The larval epithelial cells do not then become the choanocytes. Only their nuclei are specifically determined. The bodies of the choanocytes are picked out of the general syncytium in accordance with the location which the nuclei may occupy at the time. Non-nucleolate cells of the interior break through to the surface and form epidermis. Or non-nucleolate nuclei, usually not in special cell bodies but in the general syncytium, are drawn to the surface, the surface layer there condensing to form epidermis.There is a provisional formation of limiting membranes by the reticular syncytium around spaces of the interior and at the surface. The definitive cellular membranes, epidermis and canal epithelia, are only completed later. Some mesenchyme cells may be digested by the general syncytium. Such cells lie in vacuoles, as in a digesting protozoan.
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  • 96
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    Journal of Morphology 58 (1935), S. 385-417 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The anatomy of the lymphatic system of the snake is described, together with some preliminary observations of the blood vascular system. Lymphatic vessels are numerous and thin-walled, chiefly periangious, but some are in close relation to the vertebral, column. The aortic lymphatic enlarges to form a sac in the abdominal region which encloses several of the viscera and in many cases communicates with their connective tissue sheaths. Lymph vessels in the skin and body musculature form a regularly arranged segmental network. The system communicates with the blood vascular system in two places: by means of a pair of posterior lymph hearts in the region of the cloaca, and at the jugular lymph sac just craniad to the heart. The arrangement and distribution of lymphatic structures is of interest in relation to phylogenetic development and because of the specialization of structure due to the elongate form of the snake.
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  • 97
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    Journal of Morphology 58 (1935), S. 463-535 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A histological study has been made of the developing mid-gut or mesenteron of Melanoplus differentialis from diapause until after hatching. The primitive mid-gut consists at first of a single layer of squamous epithelium surrounding the yolk; to this is added later an outer layer. These two layers give rise to the muscular and connective tissue elements of the definitive mid-gut. Near the time of hatching, vitellophages which have been present in the yolk since earlier stages migrate peripherally to form a lining upon the inner surface of the primitive mid-gut. The vitellophage nuclei divide to form the smaller nuclei of the definitive epithelium of the mid-gut. The development of the definitive mesenteron from the primitive mid-gut takes place rapidly and occurs near the time of hatching.
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  • 98
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ‘germinal crescent’ of the primitive streak stage chick embryo is located in the zone of junction anterior and lateral to the proamnion. The primordial germ cells supposedly arise from this area.The following experiments were carried out. 1. Complete removal of the germinal crescent. 2. Partial removal of the germinal crescent. 3. Removal of areas of corresponding size of the blastodisc other than the germinal crescent.The results are as follows: In experiment 1, a careful search of the entire specimen failed to reveal any primordial germ cells. Such embryos invariably died during or before the fifth day of incubation.In experiments 2 and 3, the presence of the primordial germ cells was quite obvious. Such embryos did not invariably die. Some from each group was brought through to hatching, with the exception of that group in which the piece was taken from the lateral region of the blastodisc. In this case the injury to the circulation was too great to overcome.As was to be expected, in those specimens in which the circulatory system was injured rather severely death always ensued and occurred before the third day of incubation regardless of the type of experiment.Both cauterization and removal with scissors were tried. Mechanical removal gave superior results and was used exclusively in the latter part of the experiment.
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  • 99
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 58 (1935), S. 615-637 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Chordotonal organs are present in the prothoracic, mesothoracic and metathoracic femora of Melanoplus differentialis. These have been described and their development traced from ectodermal invaginations located at the proximal and distal ends of the prothoracic and mesothoracic and at the distal end of the metathoracic femora of the embryo.
    Additional Material: 5 Ill.
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  • 100
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 62 (1938), S. 141-175 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper is based on information derived from a sectioned skull of Cynariops robustus Broom, a prepared skull of Cynariops longiceps Olson, prepared and sectioned specimens of Captorhinus, Dimetrodon and various cynodonts, and the literature dealing with these forms.In the otic region, it is shown that the internal auditory meatus, the fallopian aqueduct and the semicircular canals change but little in the series from Captorhinus to the cynodonts. Certain structures, the fenestra ovalis, which becomes progressively smaller, the vestibule, which lies progressively more ventral to the floor of the brain case, the recessus lagenacochlea, which increases in size, and the prootic, which enlarges, show progressive change. The fenestra rotundum is discussed at length. It is absent in Captorhinus, just back of the fenestra ovalis in the Gorgonopsia and Dimetrodon, and confluent with the foramen jugularis in the Cynodontia.The length and relationships of the parasphenoid in the Gorgonopsia are offered as evidence supporting the theory of the homology of the reptilian parasphenoid and the mammalian vomer.The sphenethmoid complex in Cynariops is divided into two elements, a basal member, the presphenoid, and a dorsal member, identified as the orbitosphenoid but possibly incorporating a portion of ossified mesethmoid as well.The comparative studies point out certain basic trends of evolution in the Synapsida, and indicate the level of evolutionary development of the groups studied.
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