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  • Cell & Developmental Biology  (154)
  • Earth model, also for more shallow analyses !  (8)
  • Aircraft Design, Testing and Performance  (4)
  • 42.75
  • AERODYNAMICS
  • Animals
  • 1935-1939  (119)
  • 1930-1934  (47)
  • 1935  (119)
  • 1930  (47)
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  • 1935-1939  (119)
  • 1930-1934  (47)
Year
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 49 (1930), S. 385-413 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structure of the living blood cells is described and the cells are classified in the following species of ascidians: Phallusia nigra, Ecteinascidia turbinata, Clavelina oblongata, Symplegma viride. Evidence for the genetio relationship of the various types of cells is discussed.
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  • 2
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 49 (1930), S. 455-507 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The history of the cytoplasmic components in the spermatogenesis of Gerris is, in general, like that which has been described in the Pentatomidae. The observations of fixed material have been checked by extensive studies of freshly teased preparations. During the spermatocyte growth period the chondriosomes undergo considerable increase in mass. During the maturation divisions the chondriosomes are remarkably constant in orientation with respect to the centrioles. The nebenkern arises by fusion of chondriosomes differentiated into chromophilic and chromophobic portions. The Golgi bodies of the earlier spermatocytes are vesicular bodies, the peripheries of which are osmiophilic. These are not visible in fresh preparations, but the masses resulting from their fusion in the late prophase of the first division are visible in the unfixed cells. The non-osmiophilic material inside these masses stains with neutral red in fresh preparations. Only the osmiophilic part of the Golgi masses is involved in the fragmentation to form dictyosomes. There is very suggestive evidence that the process of acrosome synthesis largely takes place inside the sac-like acroblast (Golgi apparatus). In the spermatid, material which stains, in fresh preparations, like the acroblast is never seen, except inside or attached to the acroblast, where it appears in the form of small spheres of ‘pro-acrosomic’ material, which fuse to form the acrosome.
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  • 3
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 49 (1930), S. 579-619 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Haemichromis bimaculata is a tropical teleost fish which will produce eggs practically throughout the year at intervals of from three to four weeks. These eggs are of suitable size and character for embryological study, the features of special interest so far discovered being as follows: (1) The egg is oval; (2) it is attached to a substratum by its side, the blastopore being at one end; (3) the embryo always tends to develop along the side opposite that originally next to the substratum.Results obtained by reorienting the eggs previous to cleavage, and by centrifuging them, seem to show that the relation of the embryonic axis to the egg is determined either previous to laying or very soon afterward, possibly by the relation to the substratum, and is not subsequently affected by gravity or other known factors. There may be some tendency for the first cleavage plane and the sagittal plane of the embryo to coincide, but such coincidence is not at all constant or exact.
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  • 4
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 127-142 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Color changes in Palaemonetes had been found to be inhibited in the whole abdomen by occluding the dorsal abdominal artery. Inasmuch as these chromatic responses are brought about by means of circulating hormones, it should be possible, in view of early anatomical findings, for specific substances to reach the abdomen by way of the ventral abdominal artery which has been described for so many decapod crustaceans. This paper reports a degenerate ventral abdominal artery and a ventral continuation of the dorsal abdominal artery, the latter thus being distributed to practically the entire abdomen and therefore chiefly responsible for abdominal color-change phenomena.A method is given for injecting the arteries of small crustaceans, and the entire arterial system of Palaemonetes is described and figured. Several hitherto unreported vascular structures are noted: a plexus of blood vessels surrounding the supra-oesophageal ganglion, certain branches of the ophthalmic artery leading to the eyes, and various branches of the dorsal abdominal artery in the region of the telson and uropods. The forward flow of blood in the ventral portion of the abdomen in decapod crustaceans is held to be unique.
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  • 5
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930) 
    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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  • 6
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Histological changes which occur in the digestive system and its appendages and in the muscular system of the honeybee during metamorphosis are described. Some attention is given to changes which take place in the fat-body, the silk-glands, and the reproductive system. Material of known ages was used. Observations began with the sealing of the larva in its cell and were concluded with the young bee ready to emerge from its cell. Soon after the larva is sealed in its cell, the body tissues begin to undergo a change. Larval epithelial cells lining the midgut are cast into the lumen and they are replaced by cells which proliferate from the imaginal or ‘replacement’ cells. In the fore- and hindgut the lining of the larval cells is replaced by imaginal cells whose points of origin are probably at the anterior and posterior ends, respectively, of the midgut. While the imaginal lining is being formed, the opening from the midgut into the hindgut is closed by a small portion of tissue. A part of the larval muscles are histolyzed and then re-formed from imaginal myoblasts, other larval muscles disappear entirely. The strictly imaginal muscles (e.g., leg muscles) are formed by myoblasts which congregate at the point of muscle formation. There is no evidence of phagocytosis in the honeybee during metamorphosis.
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  • 7
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 341-359 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The growth of chick embryos of heavy and light breeds and the reciprocal crosses between them is described. The embryos of the heavier breed and the hybrids were found to be somewhat heavier than the embryos of the lighter breed from the tenth day of incubation to hatching time. In eggs of the same weight from the two breeds the size difference tends to disappear toward hatching time, probably due to the equivalence of the strictly limited food supply. It is pointed out that the size difference is more probably due to difference in the proportion of cells dividing at a given time than to a difference in duration of mitoses.The mortality of the hybrid embryos was intermediate between that characteristic of the parent breeds, while the percentage of monsters in the hybrids was less than that for either parent breed. There is thus some indication of heterosis.
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  • 8
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 475-495 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Four species of iceryine coccids have been studied cytologically in connection with certain breeding experiments. These are Icerya littoralis, Icerya montserratensis, Echinicerya anomola, and Crypticerya rosae. For the three first-named species the complete chromosomal history has been established, and the evidence on the fourth, Crypticerya rosae, is sufficient to indicate that it differs in no essential respect from the others. The following résumé may, therefore, be considered to apply to all four species. The females are diploid, with a chromosome number of four, and the males are haploid, with a chromosome number of two. Oogenesis proceeds quite normally; two tetrads are formed and two maturation divisions occur in which the chromosomes are reduced to two in each female pronucleus. All eggs undergo this reduction: if the eggs are then fertilized, the diploid number is thus restored and development into females ensues; if the eggs remain unfertilized, whether in the body of a virgin or of a fertilized female, they develop parthenogenetically, with no restoration of diploidy, into haploid males. The spermatogenesis of the haploid males involves a single meiotic division, demonstrably equational in character; the accompanying cytoplasmic division is suppressed, and from each of the binucleate spermatids thus produced two spermatozoa are formed. These conditions are contrasted with the functional hermaphroditism and haploid parthenogenesis of Icerya purchasi.
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  • 9
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 569-611 
    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 upon a close series of ontogenetic stages from cleavage until after metamorphosis.The so-called primordial germ cells, first differentiated in the lateral mesoderm, are traced to a definitive position in the genital anlagen. Careful counts of these demonstrated that they exist in larger numbers in the younger stages and that few of them ever reach the genital anlagen where they may form a small portion of the propagative cells.Evidence is presented that the majority of the germ cells are of somatic origin. From the earliest appearance of the indifferent gonad certain cells in the germinal epithelium have been observed which were increasing markedly in size and undergoing the various changes necessary in the transformation of small cuboidal or spindle-shaped peritoneal cells with oval nuclei into large germ cells with immense polymorphic or lobate nuclei. These cells are abundant in all older individuals. All the successive stages in the evolution of a somatic cell into a reproductive cell, involving as it does an increase in size, changes in shape, and a new distribution of chromatin material, are demonstrated.
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  • 10
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The various stages in the life history of Cryptocotyle lingua are identified and described. Adults naturally occur in the intestine of fish-eating birds and mammals. They were experimentally obtained in the cat, white rat, and guinea-pig. The development of the miracidium was followed within the egg. Larval stages occur in the marine snail, Littorina littorea. The structure of the redia and cercaria is described in detail, and evidence is submitted to show that the cercaria is identical with Cercaria lophocerca Lebour, described from the same snail on the British coast. Penetration and encystment of the cercaria in the skin of the cunner were experimentally secured. Excystment of the metacercaria was obtained both in experimental animals and in vitro. The metacercariae were maintained in culture media for as long a time as is required for them to attain sexual maturity in the final host. The host relations and specificity of the parasite are discussed on the basis of infection experiments. The cercaria is compared with similar larvae and its taxonomic position determined.
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  • 11
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 497-515 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Our observations confirm the recent findings of Krjukowa ('29) on the specific character of the Golgi material in the salivary glands of the Chironomus larva and are therefore in disagreement with the findings of Parat and Painlévé ('24).The Golgi material in the salivary glands of the Chironomus larva is present as discrete bodies having the form of crescents, rings, and rods. These are evenly deposited throughout the gland and show no makred variation in number at different stages of the physiological activity of the gland.The mitochondria are present in the form of filaments frequently concentrated in the area surrounding the nucleus and at the periphery of the cell.Neutral-red staining was never observed to color the Golgi bodies. It is suggested that the neutral-red bodies may represent the secretory material. However, it is clear that, whatever the significance of the neutral-red bodies, they are not Golgi material. Accordingly, this evidence supports the view that the Golgi apparatus, mitochondria, and neutral-red bodies are morphologically distinct structures in the cells of the salivary glands of the Chironomus larva.
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  • 12
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    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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  • 13
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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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  • 14
    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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  • 15
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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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  • 16
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    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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  • 17
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    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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  • 18
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    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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  • 19
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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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  • 20
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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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  • 21
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    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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  • 22
    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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  • 23
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    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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  • 24
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    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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  • 25
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    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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  • 26
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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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  • 27
    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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  • 28
    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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  • 29
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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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  • 30
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    Journal of Morphology 49 (1930), S. 153-221 
    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 made of the morphological types of the second, third, and fourth interdigital patterns of the human palm and their differential occurrence as a basis for determining the morphological significance of the digital triradii and main lines, which are the final remnants of the pattern boundaries. Certain types of patterns show a large preponderance, with a correspondingly large percentage of a certain morphological value for each digital triradius, although other morphological possibilities than the usual one are discovered in each case. Correlated combinations of rare patterns are presented and their hereditary nature discussed.
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  • 31
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    Journal of Morphology 49 (1930), S. 251-275 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Intravitam stains were used to determine the functions of several organs in two species of nemas (Rhabditis strongyloides and Rhabditis elongata). The organs were also studied in section. From the results obtained it is concluded that the amphids are not excretory in function, but more probably sensory, for definite connections were observed to extend to the nerve ring. No migratory cells, such as those described by Stefanski, were seen.The phasmids stained with all intravitam stains used. but were never observed to secrete. It seems doubtful that they serve as excretory organs.The excretory system was seen to consist of a typical X system. Actual excretion was observed. Deirids were seen for the first time in both species. Oesophageal glands were also described. A study was made of the structure of the intestinal cells, rectal glands, and anal muscles. Attention was called to the fact that there are two kinds of ejaculatory glands, one of which probably serves as a ‘cement gland,’ while the function of the other is still in doubt.
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  • 32
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    Journal of Morphology 49 (1930), S. 355-383 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The breeding season of Bugula flabellata extends from June 10th to November 15th. The young embryos develop in brood pouches (ovicells) and are finally expelled from the colony as swimming embryos. They come from the colonies at dawn or early morning. After a free-swimming period of four to six hours, each larva becomes attached and after a profound metamorphosis which involves the loss of larval organs, it develops into the bryozoan colony by budding.The larvae at first are positive to light, but become negative before attachment. Their behavior is described in detail and the mode of attachment is explained.After the larva has become attached a period of rapid growth by budding ensues. The rate of growth is given in a table in which it is shown that the first individual of the colony is completed in two days and that a new series of buds is formed every two days. There are eight or ten individuals after one week and over a hundred in two weeks. In one month the colony is half-grown and becomes sexually mature. A colony becomes senescent in three months, when it measures 112 to 134 inches in diameter.Younger colonies hibernate successfully and resume growth in early May, when new polypides are formed.
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  • 33
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The germ cells in human embryonic ovaries arise by proliferations from the germinal epithelium. These cells pass through the early maturation phases, including synizesis, beginning at about the third month. Four distinct periods may be distinguished in ovogenesis, each having its own peculiar characteristics: the early embryonic period from seven weeks to three months, the middle embryonic period from three to five months, the late embryonic period from five to seven months, and the adult period. The early embryonic period shows only growth and multiplicative phases; the middle embryonic period is distinguished by maturation phases, among which phases are interpolated which do not appear elsewhere in the species; the late embryonic period is charcterized by phases similar to those of the adult male germ cells, and the adult period by the omission of early maturation phases preliminary to the maturation divisions.
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  • 34
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    Journal of Morphology 50 (1930) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 35
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The first of a series of studies on the comparative histology of the digestive tubes of fishes selected, on the basis of their feeding habits, from the teleost group: a study of the microscopic anatomy of the digestive tube of a predaceous teleost, the sea bass (Centropristes striatus (L.)). Based on studies of sections, with details of gross anatomy from both fresh and preserved material. Includes a short survey of previous work. Deals with the histology of the various regions of the tract, their tunics and tissues, together with details of cell structure and arrangement. Approach is made from the physiological side, with particular reference to the adaptation of histological elements to functional activity. Parts treated in detail are esophagus, cardiac and pyloric limbs of the stomach, intestine, and pyloric caeca. Particular stress is laid on the histological structure and arrangement of the tunica mucosa, especially in relation to digestion and absorption. Topics given particular emphasis are: condition of mucosal folds with reference to the amount of food present in the lumen; transformation between adjacent epithelia of different types; structure of cardiac and pyloric glands; origin and differentiation of intestinal goblet cells; comparisons between histology of pyloric caeca and that of adjacent intestine, together with general conditions found in the caecal mucosa.
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  • 36
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    Journal of Morphology 49 (1930) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 37
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    Journal of Morphology 49 (1930), S. 139-151 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In Trichamoeba sp two types of inclusions are recognized on the basis of reaction to vital dyes and tomethods of osmic and silver impregnation. Globular inclusions, which are stained selectively with neutral red, may be blackened under direct observation by exposure to osmic vapor in hanging-drop preparations and demonstrated by osmic and silver impregnation. Rod-like and granular mitochondria, stainable vitally with Janus green, may be distinguished from the neutral-red globules in preparations stained with a mixture of Janus green and neutral red, and are demonstrated by Regaud's chondriosome method.
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  • 38
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Spining in Galleria begins shortly after hatching and continues throughout larval life. The gland cells secrete continuously, irrespective of the act of spinning.The nucleus plays a direct and an importnat rôle in silk secretion by the migration of nucleoli into the cytoplasm, where they enlarge and synthesize a fatty material in the center; the fatty material is transformed into a non-soluble basophllic substance, which then changes into the secretory product in its final form. The processes of converting the fat into non-soluble substance and of converting the latter into the secretory product progress inwardly from the periphery of each secretory body. The secretory bodies or masses of secretory material break up into smaller and smaller masses and eventually into a fine dispersed state before their entrance into the lumen of the gland.The mitochondria are granular in the cells of the conductive portion and filamentous in those of the reservoir and secretory portions of the gland. In the secretory portion they are orientated with the long axis toward the gland lumen. Their rǒle in silk secretion is negligible or at most a minor one.The Golgi apparatus is in the form of discrete ring- and half-ring-shaped bodies and remains so during all stages of secretion. If it plays any rǒle in silk secretion, the fact has not been detected by the author.
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  • 39
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    Journal of Morphology 50 (1930), S. 453-473 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ovaries of adult albino rats were studied, the following phases being considered: Eleven to twenty and one-half days pregnant, shortly after fertilization, oestrus, not pregnant, young sterile, old, and senile. Some new ova are produced from the germinal epithelium during pregnancy and oestrus, but it is in the ovaries of non-pregnant animals between oestrous periods that the germinal epithelium is most active. There can be no question of the formation of new ova during adult life, for there is a correlation between the activity of the germinal epithelium and the number of oocytes and young follicles present in ovaries. Also one can trace the origin of ova in the surface and follow their transformation and movement into the ovary proper. In some sterile young animals little new formation took place, in others a good deal. In old and senile animals the germinal epithelium continued to be active, especially in producing ingrowing cords of cells, but frequently these were anovular. The germinal epithelium may form different types of cells by ingrowth: ova, follicle cells, and interstitial cells, but the formation of anovular follicles at one period does not prevent a later production of normal ova and follicles.Some new ova are produced from the germinal epithelium of ovaries during pregnancy and oestrus, but it is in the ovaries of non-pregnant animals between oestrous periods that the germinal epithelium is most active. There can be no question of the formation of new ova during adult life, for there is a correlation between the activity of the germinal epithelium and the number of oocytes and young follicles present in ovaries. In some sterile young animals little new formation took place; in others, a good deal. In old and senile animals the germinal epithelium continued to be active, especially in producing ingrowing cords of cells, but frequently these were anovular. The germinal epithelium may produce different types of cells by ingrowths - ova, follicle cells, and interstitial cells - but the formation of anovular follicles at one period does not prevent a later production of normal ova.
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  • 40
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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 of the cytological changes occurring in the larval oenocytes of Galerucella nymphaeae Linn., correlating those changes with the molting cycles. Preceding each larval molt, vacuoles, apparently of nuclear origin, are found in the cytoplasm from which they are eliminated at the time of the molt. The accumulation of vacuoles is not so striking at the times of pupation and the emergence of the imago, but occurs nevertheless. Beginning with pupation or just previous to it, the larval oenocytes seemingly undergo a process of deterioration, decreasing in size and presenting a ragged appearance.The fat-cells are closely associated morphologically with the larval oenocytes, and it seems that there is a probable physiological relationship also, since the fat-cells undergo a series of changes at the same time the oenocytes are exhibiting their cyclic behavior. Furthermore, it has been observed that in many instances there is a greater accumulation of vacuoles in that part of the cytoplasm of the oenocytes which is adjacent to the fat-cells than elsewhere.
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  • 41
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    Journal of Morphology 49 (1930), S. 415-453 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The male and female germ cells of Polygra appressa were found occurring together in the acini from the time the snails were 5 mm. in width onward, and their development traced backward to the gonial stage, in which the aspect of the female cells, present in small numbers in the acinus wall, and the male cells, in greater numbers in the lumen, seems identical.In oocytes, differentiation involves the enormous increase in volume of cell, nucleus, and plasmosome; the appearance of yolk and of a secondary nucleolus attached to the first one, and, in some cells, various other nucleoli, attached to the chromosomes. Meanwhile the chromosomes become diffuse and spread into the interior of the nucleus, finally condensing again on the periphery. The employment of various technical methods produced interesting variations in the aspect of oocyte chromatin and nucleoli.The appearance of the Nebenkern in spermatocytes during the growth period was noted, but no indication of its presence discovered in oocytes until the fairly late growth period.The chromosome forms were noted in spermatogonia, first spermatocytes and oocytes, and their numbers found to be 61 63, 31, and 31, respectively, but no clear dividing oogonia were found, on which similar observations could be made.
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  • 42
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    Journal of Morphology 50 (1930), S. 71-126 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An extensive survey of the anatomy of the endolymphatic organ (i.e., endolymphatic sac and duct) has been made on thirty-four species of amphibians.1The histological structure is similar throughout the group; the sac being formed of cubical cells, which grade into the columnar cells of the duct. A part or the whole of the duct is formed of peculiar ‘ependyma-like’ cells.2The organ typically arises from the sacculus, extends to the endolymphatic foramen by which it enters the endocranial cavity. Here the sac-like expansion of the organ lies in the extradural space.3Six morphological types of endolymphatic organ may be recognized in the Amphibia.4The development of the endolymphatic organ of four of these types has been followed. The structure in each case may be considered to have reached its definitive condition at the time of metamorphosis.5The types of sac structure cannot be readily correlated with any habit of the animals possessing them.6A discussion is given of the homology, comparative morphology, and function of the organ throughout vertebrates.
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  • 43
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    Journal of Morphology 50 (1930), S. 259-293 
    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 ear of the common dogfish from the 3.5-mm. stage to the adult, with a brief review of the literature and comparison with related forms.The study includes the following topics: First indications of vesicles. The beginning of specialization. The separation of component structures. The sensory epithelium. The structure of the adult ear, including a description of the sensory areas, the innervation, the lagena.The position of the future canals is first indicated in 15- to 20-mm. stages. The sacculus and utriculus were first noted in the 22-mm. stage. Complete separation of the canals, the sacculus, utriculus, the recessus utriculus, and the lagena has occurred by the time the 33-mm. stage is reached. Definite innervation of the ampullae is found at this stage.The article contains twenty-seven figures; eight of them are drawings made from wax reconstructions of various stages.
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  • 44
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    Journal of Morphology 50 (1930), S. 361-392 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This ontogenetic study shows the following facts: (1) the presence of a vidian artery homologous with that of reptiles, which serves visceral elements of the jaw; (2) there exists a transitory occipital artery arising from the stapedial which contributes to the vascular supply of the occipital region; (3) the presence of a transitory fifth arch intimately associated with the sixth arch; (4) there is evidence of at least two presegmental branches of the aorta; (5) in the development of the adult pulmonary stem the right artery forms very little of the common vessel; (6) a single cephalobrachial trunk forms the culmination of arch development; (7) arterial development of the head and neck falls into three phases: (a) a temporary arterial pattern designed to carry nutriment to primitive head structures, (b) a plan of arterial distribution adapted to supply the rapidly forming cartilage and muscle of the jaws, and, (c) a readjustment period when the arterial plan is readjusted due to the increased heteronomy of the head.
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  • 45
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    Journal of Morphology 50 (1930), S. 413-451 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The process of ‘chromatin diminution’ may be said to be a casting off of chromatic material from the chromosomes earlier or later in the course of mitosis. A study of the phenomenon as it occurs in Ephestia and Ascaris shows it to be comparable in only the broadest and most general sense.In Ephestia the diminution substance is not formed in the nucleus, but is due to a later differentiation of the chromosomes long after their discharge from the nucleus. This can be made apparent by the use of differential stains and by other methods.In Ascaris diminution is found not to occur until the third cleavage, and then in all three cells that are destined to be somatic. The diminution process in this instance is apparently comparable to the casting out of residual substance which occurs when the nuclear vesicle breaks down in other cells.
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  • 46
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    Journal of Morphology 50 (1930), S. 517-525 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fertilized hen's eggs of known origin were incubated under predetermined, standardized, and uniform conditions of all physical factors except air, the composition of which in respect to the carbon dioxide and oxygen varied in each experiment. The growth and mortality of the embryo were studied daily, with, on an average, four observations.The experimental data show that the continuous exposure to about 0.4 per cent of carbon dioxide in the air of the incubator stimulated growth during the first part of embryonic life. A high content of carbon dioxide and at the same time a slightly reduced content of oxygen resulted in diminishing of the size and increasing of mortality of the embryo. The maximum combined proportions of these gases possible for growth of the embryo were about 22.0 and 16.3 per cent, respectively. A temporary exposure (twenty-four and forty-eight hours) to a large amount of carbon dioxide resulted in diminishing the size of the embryo without apparent deformities or increase of mortality.
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  • 47
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    Journal of Morphology 57 (1935), S. 275-302 
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    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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  • 48
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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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  • 49
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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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  • 50
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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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    Journal of Morphology 58 (1935), S. 157-172 
    ISSN: 0362-2525
    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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  • 52
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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
    Topics: Biology , Medicine
    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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  • 53
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    Journal of Morphology 58 (1935) 
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  • 54
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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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  • 55
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    Journal of Morphology 58 (1935), S. 419-437 
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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 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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  • 56
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    Journal of Morphology 49 (1930), S. 333-353 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The current view in mammals is that ova are formed in the embryo in large numbers and stored in the ovary as a reserve to be drawn on through adult life; they may persist for long periods ina latent condition, a few resuming active development at each recurring oestrous period; new ova are not and cannot be added.An alternative hypothesis has been presented by several authors: New ova are formed throughout life, from the embryonic period through the time of sexual maturity; each ovum so produced must at once begin its growth and development of die; long latency of oocytes and primary follicles is not possible and does not occur. There is a constant degeneration of most follicles, and only a few come to ovulation. A study of the albino rat presents evidence which is consistent with the second view and supports it more strongly that it does the older hypothesis. Similar evidence is found in other mammals. It seems probable that the newer hypothesis is the correct one, at least in some mammals; further investigation may show it to be of general application.
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  • 57
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    Journal of Morphology 49 (1930), S. 223-249 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: During the course of a hydrobiological survey of Monterey Bay, California, a series of pelagic organisms was taken at a depth of approximately 350 M., which appears to be a link connecting the Echiuroidea (Gephyrea armata) on the one hand and the polychaetes on the other. The range in body length is from 5 mm. to 27 mm.; and in an extended condition the anterior end of the body, with its palps and cirri, bears a close resemblance to a nereid. The supra-oesophageal ganglia and the ventral nerve cord, with eleven pairs of ganglia, are also strikingly annelidan in character. On the other hand, the spacious coelom, communicating with the exterior by a pair of anterior nephridia, allies it with the gephyreans. The same is likewise true of the gonad, which arises from the coelomic epithelium surrounding the genital vessel. The various systems are described in detail, and their resemblances to those of other annelids are indicated. This new species, Poeobius meseres, is made the representative of a new family, the Poeobiidae, which, provisionally at least, is included in the Echiuroidea.
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  • 58
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    Journal of Morphology 49 (1930), S. 277-331 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The entire ovary, including its germ cells, is produced by a local proliferation of peritoneal cells. The germ cells of the embryonic ovary grow, divide, become grouped into nests, pass through synaptic changes, and become primary follicles by three days after birth. At that time, growth of all the ova and follicles begins, and this results in a normal maturation, then a degeneration of all the ova by about thirty-two days after birth; few, if any, of the original germ cells remain after this degeneration. About twenty-three days after birth, there begins a great activity of the germinal epithelium in forming new ova, reaching its maximum between thirty-six and thirty-nine days, but continuing into the adult animal.The definitive ova of the adult are transformed peritoneal (germinal epithelial) cells formed anew during the late youthful and adult life. This occurs chiefly by a local enlargement of single germinal epithelial cells which become surounded by follicle cells and push into the ovary; there is also the production of ova from ingrowing cords of the surface layer of the ovary. The original germ cells pass through synapsis and other meiotic changes in late embryonic and early postnatal periods, but these all degenerate; synapsis cannot be distinguished later than three days after birth. But it is possible to follow, in young and adult ovaries, the transforming germinal epithelial cells into ova which pass through normal maturation and ovulation; therefore, these must be considered as true ova, which they are in fact, even though synapsis cannot be observed in their history.
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  • 59
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    Notes: A survey is made of the literature pertaining to lymph systems of the various groups of trematodes in which they occur, together with descriptions of the lymph systems in several forms not previously studied. The author reports the presence of a lymph system in two families, Cyclocoelidae and Heronimidae, which heretofore were considered to be without such organs, and the significance of this characteristic feature of certain trematodes is discussed as bearing on the problem of the evolution of monostomes, amphistomes, and other distomes. The gross morphology and the histology of the structural units of the system are described for Paramphistomum stunkardi, an amphistome from a fish, and for Diplodiscus temporatus, an amphistome from an amphibian, together with observations on the ramifications and structural components of the system in Cotylophoron cotylophorum. Various theoretical considerations concerning the development, function, and taxonomic and phylogenetic significance are treated on the basis of the morphology of the system and its resemblance to certain components of the vascular system of higher forms. The lymph system in trematodes is the natural starting-point in any study of the phylogenetic development of vascular systems.
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  • 60
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    Journal of Morphology 50 (1930), S. 193-208 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The retina of Phrynosoma cornutum bears fovea, pecten, and many varieties of cones. The light band visible in fresh retinae beneath the slit of the eyelid corresponds to a zone of action current responses characterized by a low ‘B’ rise (negative response of Chaffee.) The lack of response from pecten and fovea is due to leakage and failure to tap ganglionic fibers.Relief maps for ‘on’ and ‘off’ effects of the ‘B’ rise were prepared.Diagrams of retinal response in cross-sections were compared with corresponding curves showing density of cone distribution. In general, the height of response is inversely proportional to the density of cone distribution.The potential change due to photochemical reaction in the average rod is on the order of 23 billionths of a volt for the ‘on’ effect and 11 billionths of a volt for the ‘off’ effect.
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  • 61
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    Notes: Number of chromosomes is 13 (♂) and 14 (♀), the same as in biparentally produced relatives. In diploid groups from partheno-produced individuals homologous chromosomes tend to lie together, as ‘doubles’ or separated but near each other. In biparentally produced individuals they have as marked a tendency to lie in oppósite halves of the plate. Chromosomes of an individual tend to persist in the same position from cell to cell in the partheno-produced, with homologues side by side arranged about one center; in the biparentally produced, with seven single members arranged about each of two centers. In the partheno-produced the cells of younger animals, or of the earlier stages of organs in older animals, have a larger proportion of ‘double’ chromosomes or closely associated homologues.These conditions suggest that the partheno-produced individual arises from an egg with a single pronucleus in which there were seven ‘double’ or diad-like chromosomes, and the biparentally produced from an egg with two pronuclei, each with seven ‘single’ chromosomes. The paired position of homologues in Diptera may be due to synapsis-like tendencies in early cleavage, either as ‘hang-over’ effects from the preceding meioses or a different type of synapsis mechanism in Diptera. Partheno-produced male tettigids may be accounted for through non-disjunction among the four parts of the sex tetrad.
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  • 62
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    Notes: Experimental studies on the responses to light in Mya arenaria L. indicate that photosensitive tissue is located somewhere near the inner surface of the siphon and that the siphon is sensitive throughout its entire length.A histological study of the siphon shows cells of a special type in the photosensitive region, which are most abundant where the inner surface of the siphon is most sensitive. They are found throughout the length of the siphon, just beneath the inner epithelial layer, around both the incurrent and excurrent siphons. They receive nerve elements from branches of sixteen large nerves.Each cell contains a characteristic inner structure, the optic organelle, composed of a rather large hyaline structure, the lens, which is surrounded by a network of nerve fibrillae, the retinella. Light rays, reflected from a flat mirror through the lens in these cells, are brought to a focus in the region of the retinella, irrespective of the direction of the rays.The cells are similar in structure and function to visual cells in leeches and photoreceptors in the earthworm. Available data indicate that they function as photoreceptors and that the fibrillae of the retinella are direct receptors of light stimuli.Pigment spots found in considerable number on the distal third of the siphon, and thought by some to be eyespots, are, owing to simulation of the background, probably protective in nature, rather than functional in photoreception.
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  • 63
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    Journal of Morphology 57 (1935) 
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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
    Topics: Biology , Medicine
    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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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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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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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    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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  • 67
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    Journal of Morphology 57 (1935), S. 131-145 
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    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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    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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    Journal of Morphology 58 (1935), S. 573-583 
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    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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    Journal of Morphology 58 (1935), S. 585-613 
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    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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  • 73
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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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  • 74
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    Journal of Morphology 49 (1930), S. 45-137 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A general survey of the reaction of neutral red upon a selected series of living animal organisms is made, and the rationale indicates that neutral red is an indicator of proteolytic enzyme action, whether this be intra- or extracellular. Cellular hydrolytic and cellular synthetic systems are thus manifested. The neutral-red reaction also reveals the course of assimilation and secretion in organisms, the nature of fertilization, and the beginning of embryological differentiation.
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    Journal of Morphology 49 (1930) 
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  • 76
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    Journal of Morphology 50 (1930), S. 393-411 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the family Cottidae there is a greater variation in the shape of the sperm than has been found, with one exception, among all the remainder of the teleosts. There is an oval and a slender type of sperm with intergrading forms. The oval and the slender types vary, so that there is a more or less complete gradation from a nearly round, disc-shaped sperm to a slender, flattened sperm.Spermatid masses have been found only in some of the oval sperm forms. They have been found in seven species and subspecies of the genus Cottus and in three other genera of the family, but have not been found outside of the Cottidae. They occur in widely separated places, such as Norway and China, and in both fresh- and salt-water forms. In Cottus bairdii they are not found in all localities, their presence apparently being due to some external factor, perhaps temperature. It is highly probable that further investigation will show that in other species of the family, also, spermatid masses are present in some localities and not in others.
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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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  • 78
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    Journal of Morphology 57 (1935), S. 91-104 
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    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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    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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  • 80
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  • 81
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    Journal of Morphology 57 (1935), S. 303-316 
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    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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  • 82
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    Journal of Morphology 57 (1935), S. 317-333 
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    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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  • 83
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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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  • 84
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    Journal of Morphology 58 (1935), S. 221-256 
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    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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    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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    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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    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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    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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    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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    Journal of Morphology 58 (1935), S. 615-637 
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    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.
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    Journal of Cellular and Comparative Physiology 6 (1935) 
    ISSN: 0095-9898
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Journal of Cellular and Comparative Physiology 6 (1935), S. 387-391 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Journal of Cellular and Comparative Physiology 6 (1935), S. 181-216 
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    Journal of Cellular and Comparative Physiology 6 (1935), S. 255-261 
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    Journal of Cellular and Comparative Physiology 6 (1935), S. 317-334 
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    Journal of Cellular and Comparative Physiology 6 (1935), S. 351-368 
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    Journal of Cellular and Comparative Physiology 6 (1935), S. 425-439 
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    Journal of Cellular and Comparative Physiology 6 (1935), S. 505-515 
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    Journal of Cellular and Comparative Physiology 7 (1935), S. 23-46 
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    Journal of Cellular and Comparative Physiology 7 (1935), S. 131-136 
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