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  • Life and Medical Sciences  (395)
  • 1930-1934  (365)
  • 1905-1909  (30)
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  • 101
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    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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  • 102
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    New York, NY : Wiley-Blackwell
    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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  • 103
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 361-392 
    ISSN: 0362-2525
    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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  • 104
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    New York, NY : Wiley-Blackwell
    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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  • 105
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 517-525 
    ISSN: 0362-2525
    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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  • 106
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 51 (1931), S. 1-117 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Four functional types of viviparity are recognized, and the last, pseudoplacento viviparity, is illustrated by a review of the embryogeny of a species of Polyctenidae. This insect normally has ten embryos in the reproductive tract in successive stages of development. The problem of fertilization is discussed, for there seems to be no spermatheca and spermatic clumps are present in the haemocoel. No organ of Berlese can be found. One, apparently a nymph, when sectioned revealed spermatozoa in even greater abundance than the mature females. Four to six of her offspring would seem to be paedogenetic.Females liberate ova that are yolk-free, and no chorion is secreted about them. Blastomeres are distinct, the embryonic envelopes are formed as usual, and hemipteran embryology occurs. The trophserosa functions until blastokinesis takes place, when the pleuropodial extensions evaginate and encompass the embryo which now lies in a pleuropodial cavity. The pleuropodia function as Lutrient organs, or psedoplacenta, until shortly before birth. At birth the embryo is a little more than one-third the adult body length and bears strongly developed setae.
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  • 107
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A morphologic study of the labyrinth, especially on the perilymphatic space with its physiologic aspect, is presented in this paper. The perilymphatic space starts its development with the chondrification of the auditory capsule, and is completed by the end of the first third of metamorphosis. The author divides the whole spatium into two parts: the ductus perilymphaticus et diverticula and the pars spongiosa spati perilymphatici. The ductus perilymphaticus et diverticula may play an important rǒle in carrying out the functions of both equilibrium and audition. The pars spongiosa serves not only to fasten the membranous labyrinth to the capsular wall, but acts as a safeguard for the functions of both the membranous labyrinth and the ductus perilymphaticus et diverticula. The ductus system may have more important physiologic relations than does the membranous labyrinth in connection with the cranial cavity and spinal cord, as to the change of pressure, the transmission of vibrations, the osmosis of fluids, etc. A number of microscopic and schematic figures are shown with reference to the anatomic and morphologic relations of the membranous labyrinth, auditory capsule, and spatium perilymphaticum.
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  • 108
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 51 (1931), S. 309-318 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This investigation was made to demonstrate the direction of the current of a perfusing fluid (hence that of blood in nature) inside the so-called [renal-portal] vein of birds and to determine if this vein has any fine capillaries in the kidney substance. A domesticated male duck was anaesthetized with ether, and a warm saline (mixed with a little urea and urine) was passed through the aorta. The [renal-portal] vein was also perfused with the same fluid through the left internal iliac vein. At first the kidneys actively secreted semisolid urine, but gradually the strength of the latter varied from a milky to a watery fluid.Later, a warm carmine solution was perfused through the left internal iliac vein, and the path of the dye could be easily traced along the whole length of the left renal afferent (left [renal-portal] vein) and its final exit through the postcaval vein. The posterior lobe of the left kidney was partially tinged with red, probably due to diffusion, since the kidney substance should have taken a uniform red hue if there was any definite capillary system. The coccygeomesenteric vein contained no dye.These results (coupled with actual caliber measurements of the two [renal-portal] veins in duck and pigeon examined, the calibers of these veins increasing gradually posteroanteriorly) indicate that: 1) blood flows anteriorly in the [renal-portal] vein; 2) this vein does not break up into capillaries in the kidney substance, but receives larger affluent veins; 3) there is no [renal-portal] system in birds; 4) the urine secreted by birds is always semisolid.
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  • 109
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 51 (1931), S. 467-525 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The general morphological and histological evidence accumulated by this study suggests the following facts: 1Under out-of-door conditions, in the vicinity of Philadelphia, Pennsylvania, embryonic development begins at deposition and continues to the middle or late spring, when hatching occurs. The postembryonic development is completed during the summer. Copulation and oviposition occur in the late summer and early fall.2The embryonic development may be divided as follows: aThe prerevolution period, in which the rudiments of organs and systems are formed.bThe early-revolution period, during which the direction of the embryo in the egg is reversed.cThe late-revolation period, or time of yolk circumcrescence and completion of the dorsal wall of the embryo.dThe postrevolution period. comprising development from yolk engulfment to hatching.3The sexes are differentiated during the early- and late-revolution periods.4In the differentiation of the genital rudiments, a) the germ cells are segregated into groups; b) and indifferent mesodermal element grows in among the germ cells of such a group; c) the processes of this cell (the apical cell) form intimate connections with the processes of connective-tissue elements surrounding the germ-cell group; and, d) the covering membrane of the genital rudiment grows in between the various germ-connective-tissue cell groups, completing the rudiment of the follicle.5When the adult condition is reached the testis is functionally differentiated.
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  • 110
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 51 (1931), S. 527-543 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A vacuome (‘Golgi apparatus’) consisting of small globular inclusions has been demonstrated in Chlamydomonas sp. These inclusions may be seen in the living, unstained organism; they are stainable vitally with neutral red; they have been stained vitally with neutral red and then blackened with osmic vapor under direct observation, and they have been impregnated by osmic and silver methods without previous treatment with neutral red.The reaction of these inclusions to the iodin test for starch suggests that they may play some rǒle, possibly one of storage, in the cycle of starch metabolism.
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  • 111
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The segregation of the germ cells is related in time and differentiation to the ectoderm (ventral plate), the inner germ-band layer (lower layer) and the mesenteron (entoderm) rudiments. The inner germ-band layer is formed by invagination of cells from a median blastoporic groove and by cellular proliferations among the invaginating cells and from the median line of the ectoderm immediately caudad of the blastoporic groove. The mesenteron material is derived from inner germ-band layer material associated with the internal ends of the stomodaeum and proctodaeum. The germ cells are segregated from the lateral margins of the abdominal lobe ectoderm in the region of the amnion attachment as segmentation of the abdominal lobe is initiated. They ultimately become separated from the ectoderm cells of the lateral wall and from the amnion and migrate in a passive manner onto the coelomic sacs where they become associated with the inner walls of the sacs. When the coelomic sacs unite the germ cells and the splanchnic wall mesoderm cells form two continuous cell strands from the first to the eighth abdominal segments, inclusive. These strands form the indifferent genital rudiments. An endeavor is made to correlate the segregation of the germ cells in the grasshopper with that of various other insects.
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  • 112
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 56 (1934) 
    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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  • 113
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 56 (1934), S. 21-49 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The literature relating to the flexor and adductor muscles of the thigh and their nerve supplies, in Sphenodon, the lizards, crocodiles and mammals was correlated and new dissections made of animals belonging to the last three groups. All of these muscles can be traced as individual entities from animal to animal without loss or addition to their number, although splitting may occur. The attachments of the muscles and their relationships to one another and to the two heads of the gastrocnemius are the same in all the reptiles studied. In the mammals one group, including the adductor longus and magnus and the retractor femoralis, has migrated from the tibia between the two heads of the gastrocnemius onto the femur, and another from the ilium onto the vertebrae, the one migration being caused by expansion of the gastrocnemius, and the other by expansion of the gluteal muscles. A new lateral flexor mass has been formed from part of the reptilian ilio tibialis by migration down the fibula. The nerve supplies of the various muscles are not constant when traced from group to group, and it is suggested that a muscle receives its nerve supply from the nerve nearest to it in embryonic development, so that when a muscle has migrated the nerve supply is no longer a reliable guide to its homology.
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  • 114
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Histological studies of testes of both immature and mature individuals show that the peritoneal epithelium does not give up its proliferative capacities with the completion of testis differentiation. Certain regions of the antimesorchial surface retain their activity and continue to contribute cellular elements during testis growth. Stromal cells, germ cells, and sections of or entire seminiferous tubules originate from the peritoneum in the form of cord-like ingrowths. In this form, the proliferations of the germinal epithelium of the testes are similar to and homologous with the continuous proliferations of the germinal epithelium of the ovary.In Sternotherus, both testis and ovary differentiate out of a bisexual primordium in which the deeper parts of the germinal epithelium form an ovarian cortex. Since the germinal epithelium persists as an active part of both ovary and testis, it must be responsive to the same physiological factors of female or male differentiation respectively. It is indifferent sexually and once the direction of sex differentiation is established, the response of the germinal epithelium is in the determined direction. Its activity is then to produce either seminiferous tubules or ovarian follicles, and is directly dependent upon the processes of embryonic sex differentiation and determination.
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  • 115
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    Journal of Morphology 56 (1934), S. 295-323 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The primordia of the thymus bodies in Necturus begin to form in 7-mm. embryos. These structures arise as clumps of entodermal cells on the posterior dorsal portion of the first four visceral pouches; the first or last pouch, being rudimentary, fails to form such a primordium. All except the first of these primordia lose their connection with their respective pouches in the 16-mm. stage and lie free in the surrounding connective tissue. The primordium on the first pouch begins to show degenerative changes during that stage, losing connection with its pouch in the 23-mm. stage, finally to disappear altogether in 30-mm. specimens.The three remaining bodies continue to grow, but the second and third outstrip the fourth in development and begin to form Hassall's corpuscles in 32- to 34-mm. stages. Sections of 30-mm. Necturi show a few of these corpuscles fairly well developed and containing a faintly staining secretion. The fourth body remains relatively small a long time, not showing the Hassallian cysts until the animal is 60 mm. long. By shifting of positions and increasing in size, the three bodies come to lie in proximity, one behind the other, to form the definitive thymus gland of the adult. The gland lies embedded in the heavy musculature on top of the head in front of the gills.
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  • 116
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    Journal of Morphology 56 (1934), S. 339-359 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of vitamin E deficiency in the fowl were observed in Rhode Island Red males over a period of approximately 2 years.Mating experiments showed that after 1 year on the E-free diet all of the males were capable of fertilizing ova, but that after 2 years some of the males were sterile.Sperm smears showed that shortly after the beginning of the experiment, many of the mature spermatozoa exhibited an abnormal condition of the nuclear material of the head, while others remained normal.In histological sections of the testes made at the end of the 2 years, conditions varied from almost normal to complete atrophy, the latter being a condition that has already been described in the male mammal. Moreover, the conditions in any given section were not uniform for even in an advanced stage of E deficiency there were small islands of apparently normal tissue. However, in this case, as in the mammal, the process of degeneration affects the mature sperm cells first and gradually works to the outside of the seminiferous tubule thus attacking the youngest maturation stages last.The results of the experiment point definitely to destruction of the testis under prolonged E-deficient conditions but it is also quite apparent that the testis of the fowl is extremely resistant to vitamin E deficiency.
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  • 117
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper is an attempt to clear up the confusion concerning the osteological relationships among the Haplomous fishes.The osteology of Novumbra hubbsi was worked out by the dissection of numerous specimens. The various skeletal features found were compared with the osteology of Umbra limi, U. pygmaea, U. crameri, and Dallia pectoralis.A description of each skeletal element of Novumbra was made, followed by a description of the chief differences between it and the same structures in Umbra and in Dallia. No constant osteological differences were found between Umbra limi and U. pygmaea, and very few between these two species and Umbra crameri. Novumbra and Umbra have more in common with each other than either does with Dallia or Esox. The presence of postorbitals, postcranials, and the shape of the secondary shoulder girdle in Novumbra show it to be also closely related to Dallia and Esox.The relationships of the various forms are summarized in a synoptic key which lists the following groups: Order Haplomi. Superfamily I, Dallioidea; Family Dallidae; Genus and species, Dallia pectoralis. Superfamily II, Umbroidea; Family 1, Umbridae; Genus and species, Umbra limi, U. pygmaea and U. crameri; Family 2, Novumbridae; Genus and species, Novumbra hubbsi. Superfamily III, Esocoidea; Family Esocidae; Genus, Esox.
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  • 118
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    Journal of Morphology 56 (1934), S. 445-475 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper deals with the morphology of all the so-called gustatory and olfactory organs of blowflies, and describes tests conducted to determine whether these insects taste with their tarsi and smell with their antennae and palpi. Antennae bear two types of so-called olfactory hairs, while palpi bear only one. With the aid of an olfactometer it has been shown that antennae and palpi do not bear the olfactory organs.In order to explain the proboscis response, described by Minnich, it is not necessary to assume that tarsi bear gustatory organs, because: (1) a tarus bears no sense organs, except nine olfactory pores; (2) it is almost impossible to wet the tarsi with water or sugar water; and (3) when flies were in the proper nutritive condition and liquids were about 3 mm. from the tarsi, the insects were induced by a special method to exhibit the proboscis response. It was further clearly demonstrated by a similar method that tarsi can easily distinguish between chemically pure saccharose water and distilled water when these liquids are about 3 mm. from the tarsi. The responses, obtained by any method, are caused by two stimuli, one mechanical and the other olfactory. The act of touching the feet produces the initial stimulus and brings the liquids almost in contact with the olfactory pores on the tarsi.
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  • 119
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    Journal of Morphology 56 (1934), S. 513-531 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study of the male reproductive organs of a hemipteron, Leptocoris trivittatus, has been made. The genital system, which consists of fan-shaped testes; the vasa deferentia, to which a single pair of accessory glands are attached; ejaculatory ducts and the copulatory apparatus, is described and photomicrographs of consecutive parts presented.Then an analysis of the method of aggregation and turning of the sperms is made by means of intravitam technic. Aggregation and turning commence in the early spermatid stage. A spherical cyst forms, the tails first grow centripetally and then push out toward the lower end of the cyst. This line of growth in the cyst moves the head ends of the spermatids to the upper end where aggregation gradually takes place.The cysts spiral up and across the follicles, the moving force being, probably, the elongating tails. Later they spiral down the follicle, development progressing rapidly. The descending bundles are mature sperm, held together by a cytoplasmic cap.The accessory gland secretes a milky substance which probably activates the sperm at a later stage. Peristalsis occurs in the wall of the gland and duct.The process of massing sperm into bundles before copulation insures effective translocation. Then peristalsis and movement of tubular fluids carry the sperm down the duct to the copulatory apparatus.
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  • 120
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Glochidial cysts on the gills of immune fishes form in the same manner as normal ones, but they tend to grow larger and become more irregular. The increased thickness is due to additional cellular connective tissue in the wall. The gill tissue indicates the existing biological incompatibility only by the presence of eosinophiles, extruded chromatin spherules, and eosinophilic plastids.In natural, or racial immunity many glochidia are promptly destroyed by cytolysis, accompanied by an invasion of host cells. These disintegrating glochidia may occur in close proximity to unaffected glochidia and apparently are merely less resistant individuals that succumb to a critically adjusted reaction.In both natural and acquired immunity the normal retention of glochidia and the accompanying metamorphosis are replaced by premature shedding. After the first day, the cyst thins by the removal of stroma cells back into the filament until the wall is reduced to a thin envelope. Both intact and destroyed glochidia, and apparently their cyst coverings, are sloughed at about the second day. Repair of the resulting notched filament is prompt.
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  • 121
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Posterior regeneration in Tubifex is inhibited by suitable radiation with x-rays. Only a small knob is formed at the cut surface by rearrangement of the terminal region of the old body tissues. Location of the cut within the segment and repeated removals of segments within the posterior three-fourths of the body do not change this result. The worms are as though ‘castrated’ against regeneration. Normal worms regenerate readily under similar conditions and replace lost segments within thirty-five days. Mesodermal tissues in normal regenerating Tubifex are formed from neoblasts, which arise from peritoneal cells upon the posterior faces of septa near the cut, migrate to this wound surface, and differentiate into new structures. After radiation no neoblasts arise from peritoneal cells and there is no mesodermal regeneration. No changes, other than failure to form neoblasts, can be observed in the peritoneal cells. Migrating neoblasts are destroyed within a few hours by similar radiation.Epithelial tissues are also affected by x-rays, as shown by absence of mitoses and failure of regeneration in ectodermal and endodermal epithelia. During normal regeneration cells which form these epithelia and certain muscle fibers arise by proliferation from the epidermis and intestinal lining in the regenerating region, as shown by numerous mitoses in these layers. Failure of regeneration in radiated worms is thus related to lack of cells which are present in normal regeneration.
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  • 122
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    Journal of Morphology 53 (1932), S. 523-591 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytoplasm of the ova of ten species of insects, distributed among the Hemiptera, Coleoptera, Hymenoptera, Diptera, Orthoptera, and Neuroptera, has been studied. The Golgi bodies and chondriosomes were traced. They increase in number by fragmentation, but whether they may also arise de novo was not determined. They play no visible part in the formation of yolk or fat or any other structures or substances. Fat and yolk apparently arise independently in the cytoplasm. Vacuoles, which may stain with neutral red, may be present, but they are independent of the Golgi bodies. There is no vacuome in the sense in which Parat and others use the term. The Golgi bodies and chondriosomes are interpreted as substances rather than structures and as intermediate products of metabolism. Other bodies of unknown nature and function are present. The yolk nucleus of Gelastocoris is interpreted as a synthetic center.
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  • 123
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    Journal of Morphology 54 (1932) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Journal of Morphology 54 (1932), S. 153-160 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: The breeding season of Chaetopleura apiculata begins about June 20th to June 25th and continues until about October 1st. Spawning takes place in the early evening, 8 to 11 O'clock. The cleavage and early development are strikingly similar to that of Ischnochiton as described by Heath, and is typically molluscan. The egg is enclosed in a bristly chorion from which it hatches after twenty-five to thirty hours. The larva is a large opaque trochophore which gradually transforms into a veliger larva by the development of the shell and foot. It settles to the bottom and metamorphoses into the adult form after six to ten days. It becomes sexually mature in one year and is full grown in three or four years, when it measures 29 × 18 mm. or less.
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    Journal of Morphology 54 (1932), S. 197-220 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: The previously reported diploid number of forty chromosomes has been verified; the sex chromosomes have been shown to exist early in the growth period and to be of the X-Y type; and a chromosome-nucleolus has been described in the resting stage of the primary spermatocytes which persists throughout synapsis and divides at the time of diakinesis into two parts that are equal in size and are thought to be the largest pair of autosomes. The diakinetic bivalents have been described rather fully. These are short and heavy and assume a great variety of shapes, the most characteristic of which are ring, V, Y, cross, and hexagonal. The union of bivalents during diakinesis has been shown to be an intimate one; in every instance first chromomere unites with first chromomere or third chromomere with third chromomere. This is considered to be significant evidence of the allelomorphism of chromomeres in mammals.
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    Journal of Morphology 20 (1909), S. 461-478 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 127
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    Journal of Morphology 49 (1930), S. 333-353 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The 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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  • 128
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    Notes: Homologous chromosomes entering parasynapsis are already split. This split evidently originates in each chromosome in the resting period prior to the last spermatogonial division. In the prophase of this division the daughter chromonemata in each halfchromosome were probably incompletely separated, but the succeeding telophase effects the completion of their separation. These processes are accompanied and suceeded by an elongation, straightening, and general paralleling of the split threads and by an elongation of the cell and its nuclear space.Parasynapsis begins with intimate approximation of the daughter threads in each homologue and is continued by approximation of the homologues at the usual [bouquet] and [zygotene] periods. There results the [diplotene] thread, which therefore consists of four completely distinct strands, but which exhibits a [two-strand] appearance due to parasynapsis between daughter chromonemata being further advanced than that between homologues.The pairing process begins at the distal ends and proceeds proximally. With parasynapsis complete, the nucleus enters the [diffuse] stage On emergence, disjunction is seen to have progressed from the distal ends to near the proximal ends in each pair and the [tetrads] have taken form. In the prephase that follows each strand in a tetrad may [crimp] independently, and with the condensation and matrix (?) formation that accompany it there results the spermatocyte ‘tetrad.’
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  • 129
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    Journal of Morphology 51 (1931) 
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    Journal of Morphology 51 (1931), S. 373-433 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: An investigation into the number of chromosomes in thirty-seven species of Aphidiae belonging to twenty-seven geaera has shown that there is but one sex chromosome in the male cells of all but one species of Aphididae. That exceptional species is Euceraphis betulae Koch.The number of chromosomes and body characters are so closely correlated that we can safely judge the evolutional scale of any aphid by its number of chromosomes.In Aphididae the least number of chromosomes seems to be the most primitive.The number of chromosomes varies with the genera. The highest number is 1811 + X = 37 chromosomes, the lowest being 211 + X = 5 (diploid in male).The increase in the number of chromosomes seems to have been brought about by transverse divisions of the primitive chromosomes.The genus Tuberolachnus with 311 + X = 4 elements (♂) represents altogether different chromosomes characters from the genus Pterochlorus with 8 elements.In the genera Periphyllus and Calaphis there are species with a small m-element which is bivalent.
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    Journal of Morphology 49 (1930), S. 223-249 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    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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  • 132
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    Journal of Morphology 49 (1930), S. 277-331 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    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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    Journal of Morphology 52 (1931), S. 47-89 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: In an investigation of the hatchability of eggs from hens fed on a diet deficient in vitamin E Card found that all embryos from these eggs died during development. Study of these chicks showed that a variety of conditions were responsible for death:During early development the rate of growth and differentiation was definitely slower than under normal conditions, but malformations were rare. Some embryos died during the first two days, due to disintegration of the circulatory system or its failure to become established. At the end of the fourth day there was a definite critical period which few specimens survived and by this time distinet pathological conditions had arisen in extra-embryonic structures. These involved wiping out of the vitelline circulation by establishment of a lethal ring in the blastoderm. This structure was produced by intensive cell proliferation in the mesoderm which resulted in choking out vitelline blood vessels and their subsequent degeneration. It also caused obliteration of the exocoele, with consequent failure of the allantois to expand. In addition, many embryos showed profuse haemorrage into the exocoele. The source of bleeding was most frequently in the atrium of the heart, and at the actual rupture peculiar cells occurred which were probably histiocytic mesenchyme cells.Although death was due directly to causes enumerated above, the ultimate responsibility rests upon conditions set up by them, namely: starvation, asphyxiation, and loss of the medium (blood) by which to carry on metabolic exchange.
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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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    Journal of Morphology 50 (1930), S. 193-208 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    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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  • 136
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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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  • 137
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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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    Journal of Morphology 51 (1931), S. 435-465 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: In some insects the selection of individuals which recover in equal periods of time from immersion in water may be used to obtain material of approximately uniform physiological state; Drosophila melanogaster, Meigen, was found to have a mean of recovery for the males 0.97 ± 0.542 minute later than the females, which would indicate a lower metabolic rate for the males. The Japanese beetle, Popillia japonica Newm., was found to have a mean of recovery from immersion in water of both sexes the same in August, while in September the males were retarded by 8.1 as compared with females. This would indicate that the males have and equal me abolic rate in August with the females and a lower rate in September. Carbon dioxide, hydrogen, and nitrogen produce in the flies a condition of asphyxiation similar to immersion in water. [Vestigial] flies recover from immersion in water in a fashion similar to ‘wild’ flies.The recovery periods from immersion in water in the flies can be used to group individuals into those possessing approximately equal egg-laying capacities and to isolate spent individuals from others still capable of laying eggs. Yeast appears to be more of a stimulant to egg laying than it is to larval growth. Groups of flies which were fed yeast were found to average 71 per cent increase in egg laying over groups of flies that were not fed yeast. The O2 consumption of the groups of flies actively laying eggs, as contrasted with the groups which were not so active, was found in the former to be 32.9 per cent greater.
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    Journal of Morphology 52 (1931) 
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    Journal of Morphology 52 (1931), S. 91-113 
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    Notes: This paper discusses very briefly the ultraviolet microscope and the developments which have led to a successful technique for optically sectioning living cells; also the ultraviolet photomicrographs of living sperm cells of certain grasshoppers, which show clearly the spinning out of the chromonema from solid blocks of the diatene stage, the pairing of same in the leptotene stage, the development of the tetrads, the final distribution of the chromosomes in the resulting spermatids and their return to a spiral chromonema, each inclosed in its own vesicle. The details of the cytoplasm are equally well brought out.
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    Journal of Morphology 52 (1931), S. 165-194 
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    Notes: Neutral-red staining in Daphnia, legume seeds, starfish eggs, and Palaemonetes shows reactions to temperature changes which may be correlated with the thermal reactions of enzymes.
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  • 143
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    Notes: The oldest parts of the fibrous, cartilaginous, and bony head skeleton of vertebrates descend from the amphioxid ancestors of the myxinoid fishes. The skeleton of the velum and jaw bars of the amphioxids transform into the jaw apparatus and hyoid-velar head skeleton of the myxinoids, and some parts are passed on by inheritance to the teleostome fishes (sturgeons). These anatomical characters prove descent with modification. The theory of the origin of jaws and hyoid from branchial cartilages is not supported by the facts, as both jaws and hyoid structures were developed long before branchial cartilages furnished material for head building. The Velata, the oldest of living vertebrates, include the amphioxids and marsipobranchs, and are marked off from the higher forms by the important organ, the velum, which separates the prebranchial from the branchial head. A remnant of the velum inherited by all of the higher vertebrates is the hyoid mechanism - an important anatomical landmark.
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    Journal of Morphology 52 (1931), S. 485-511 
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    Notes: This work was designed to determine the ontogenetic variability of the morphology of mitochondria of the hepatic cell.The mitochondria of the cells of the hepatic diverticulum are minute spheres. These spheres enlarge, become associated, forming beaded filaments, which in turn become smooth filaments, the process culminating in the twenty-day fetus. There is no individual or lobular variabillty in fetuses of a given length. One-half day before birth the above process is reversed, so that separate spheres are found in the eight- to twelve-hour young. This enlargement and enspherulation are accompanied by an accumulation of large quantities of glycogen. After this age, the spheres become associated into beaded filaments again and the glycogen disappears, the cycle ending at thirty-three hours. From two to eight days of age there is great individual variability.Mitochondrial morphology characterstic of the adult is first found in the fourteen-day young, when cells contain long, smooth or beaded filaments, rods, and spheres. There is no lobular variation as to types of mitochondria, but only in numbers, the cells around the central vein containing fewer mitochondria than other cells of the lobule. Variation between individuals after birth is due to something other than age, type of food, period of digestion, and length of starvation. Fat is formed within spherical chondriosomes.
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    Journal of Morphology 52 (1931), S. 525-533 
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    Notes: There are twenty-seven spermatogonial chromosomes in Tenoder'a sinensis, three of which are larger than the others and lag behind in anaphase. These three chromosomes have been traced through the prophases of the first spermatocyte to the metaphase, where they appear as a hexad. In the first spermatocyte division two of the constituent diads of the hexad pass to one pole, the remaining one to the other, thus giving rise to two types of second spermatocytes, one with thirteen and the other with fourteen chromosomes. There are twenty-eight chromosomes in somatic metaphases of the female; four of these chromosomes are larger than the others. The sex chromosomes of the male are represented by the formula Xa + Y + Xb, that of the female by 2Xa + 2Xb.Similar conditions are reported for Mantis religiosa and Stagmomantis carolina.
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  • 146
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    Journal of Morphology 55 (1934), S. 421-433 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Paramecium caudatum was studied by micro-incineration, by stained control sections, by vital staining, and by osmic impregnation. It was found that a slow initial heating and a slow cooling after incineration greatly reduce the amount of distortion and shrinkage in the incinerated specimens. Most of the cytoplasmic components and organelles, including vacuome, chondriome, cilia, and basal granules, trichocysts, food vacuoles, and the nuclei, could be identified by their ash. No ash is found in the pellicle and only a small amount in the hyaloplasm. None of the osmiophilic components such as granules or the walls of the contractile vacuole could be identified in the incinerated specimens with certainty. The larger amount of ash in the endoplasm as compared with the ectoplasm is due to the large number of granules in the former region. The nucleus and some of the granules near the nucleus show traces of iron.
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  • 147
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    Notes: When sexually mature Procotyla fluviatilis Leidy (commonly but erroneously known as Dendrocoelum lacteum) are cut transversely into head, pharyngeal, and tail pieces of about equal length, the head and pharyngeal pieces fail to regenerate in a large percentage of cases and tail pieces never regenerate. When regeneration occurs in head and pharyngeal pieces it is somewhat slower than in similar pieces of Planaria maculata Leidy and Planaria agilis Stringer with which comparisons were made. Cutting mature Procotyla into larger numbers of pieces usually results in death of all, although smaller pieces from prepharyngeal regions sometimes regenerate. Juvenile P. fluviatilis have greater powers of regeneration, as shown by cutting head and pharyngeal regions into greater numbers of pieces, but tail pieces do not regenerate. These observations confirm and extend those of earlier investigators. Such a restricted power of regeneration contrasts with well-known powers in P. maculata and P. agilis. Counts of formative cells, from which new parts arise in all three species and which are regarded by the authors as a persistent embryonic stock, indicate about 8.5 such cells in P. maculata to 1 in P. fluviatilis per unit area. It is concluded that regeneration in planarians is correlated with numbers of such formative cells and that histological factors are no less important than physiological ones. The paper is preliminary to a study of effects of x-rays upon regeneration.
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  • 148
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    Journal of Morphology 55 (1934), S. 435-475 
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    Notes: The centrioles are recognized early in the prophase of the primary spermatocyte. They soon become double and migrate around the nucleus in opposite directions. As this is completed the nuclear membrane breaks down and spindle fibers appear. The centrioles divide in the metaphase at a time when the centrosome is still perfectly spherical. The centrosome divides in the anaphase, giving the two centers for the second division. The centriole disappears in the spermatid and cannot be seen in later stages. The behavior of the centers during the spermatocyte divisions is strikingly like that of the egg centers and other types of mitoses. Therefore, it is concluded that the centrioles of the spermatocytes are not to be regarded as different from the centrioles in other types of mitoses.The Golgi bodies increase in number and size during the growth period of the cell. They are usually found in the shape of rings. From these rings are produced the refringent granules which fuse in the late spermatid to form those of the mature sperm. It is therefore concluded that this process represents the formation of the acrosome. The mitochondria show little change during the maturation divisions. In the late spermatid they aggregate around the nucleus and become vesiculated. This is interpreted as the formation of the prenebenkern.
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    Journal of Morphology 51 (1931), S. 613-618 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The onset of hibernation in Melanoplus differentialis eggs kept at high temperatures is accompanied by a fairly abrupt cessation of cell division. The total number of mitotic figures present in the different individuals of a series of embryos of this grasshopper, from eggs kept for eighteen to twenty days at 25°C. from the time of saying, was found to vary between 1000 and 4400. In contrast to the conditions found in eggs of this age, embryos from eggs kept twenty-seven days at 25°C., as well as those older and still in the hibernating state, contained few or no dividing cells. During the course of the work it was found that, in rare cases, hibernation failed to occur, a few or many of the eggs developed without a pause when kept at 25°C., and hatched at approximately the thirty-eighth day. The detection of variations in the rate of mitotic activity over short periods, as originally planned, was found impossible, because of the comparatively small number of embryos used.
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  • 150
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    Journal of Morphology 52 (1931), S. 155-164 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Some pathological effects of supersonic waves produced by the piezo-electric oscillator described by Wood and Loomis ('27) are described.Death of fish and frogs was due to haemolysis of erythrocytes within the gill capillaries. Disruption of gill filaments, trauma, and extravasation in the head and gill region and in the peripheral musculature were noted.No effect on the nervous system was apparent histologically.Organisms were not killed in water under hyper- or hyponormal pressures. In these cases no cavitation of gases took place.Isolated frog sartorius muscle in Ringer's was not damaged.Bubbles of gas were easily observed within the muscle cells of the tadpoles when such cells were not more violently disturbed. Such bubbles were abundant in the more fluid muscles of four- or five-day tadpoles, less abundant in 15- to 35-mm. Lebistes, and entirely lacking in adult frog sartorius. Protoplasmic viscosity differences probably explain the gradient.The above-observed intracellular cavitation explains the muscular destruction, the haemolysis, the change in specific gravity of organisms subjected to the wave treatment, and may offer light upon the stimulatory effect of such waves on excitable tissues (compare Harvey, '28).
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  • 151
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    Journal of Morphology 52 (1931), S. 195-215 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this paper evidence is given in support of the author's statements (Rees, '30) that in ciliates in the genus Diplodinium a neuromotor apparatus, as described and figured by Sharp ('14), could not be differentiated. For the study of minute anatomy ciliates were cut into serial sections 3 μ thick. The body which in D. medium appeared to correspond to the motorium of D. ecaudatum was shown to be a fold of the middle layer of ectoplasm. Fibers, described and figured by Sharp as connecting the motorium to the organelles of locomotion and of food taking and to a ring about the esophagus, could not be differentiated. Other fibers which Sharp designated as opercular were shown to be part of a fibrillar complex extending throughout the middle layer and the inner boundary layer of ectoplasm. The walls of the esophagus were shown to be formed by the fused middle and inner layers of the ectoplasm. The esophageal fibers therefore belong also to the above-mentioned fibrillar complex. In D. medium a system of esophageal membranelles was differentiated, described, and figured. The ciliary systems of Paramaecium ecaudatum and of Diplodinium medium were shown to be strikingly similar. The principle of descent from a common ancestor adequately explains the above similarity, but is out of harmony with the discrepancies between Sharp's account of D. ecaudatum and this account of D. medium.
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  • 152
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    Journal of Morphology 52 (1931), S. 249-275 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The flagella of the endodermal cells of hydra have their origin in the form of a cytoplasmic spherule which appears on the cell membrane just above the blepharoplast. This spherule moves outward, and in doing so forms a small cylinder, which, in time, flattens down into a ribbon-like flagellum, the edge of which is slightly thickened. Endodermal cells were found to bear from one to five of these flagella. Dissociated endodermal cells become amoeboid and are able to move about quite freely, taking up particles of food with pseudopods; these cells are also able to elaborate flagella. In the normal well-fed hydra the endodermal cells are found to fragment endogenously; these endogenous fragments pass to the tentacles and other outlying regions, where they are taken up by the endo-epithelio cells lining these regions. The endoderm is frequently thrown into villi of quite large size: these villi, when studied over a period of days, are found to deteriorate; the cells which composed them wander to the tentacles, buds, and basal regions by means of their flagella and amoeboid movement, where they deteriorate, the cell particles being taken up by the epithelio cells lining these areas.
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  • 153
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    Journal of Morphology 52 (1931), S. 277-307 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: The most important conclusion of this investigation is that the vacuome and the classical Golgi apparatus are independent cell components in the oocytes of Ophiocephalus and Rita. The same conclusion has been arrived at by Nath in Rana tigrina. The vacuoles, the Golgi elements, and the mitochondria can be seen intra vitam side by side.In Ophiocephalus the vacuoles give rise to albuminous yolk, as has been rightly claimed by Hibbard for Discoglossus and by Hibbard and Parat for Perca and Pygosteus. The Golgi elements give rise to the fatty yolk as in so many other forms of oogenesis described by Nath and others.In Rita the fate of the vacuoles and the Golgi elements is unknown, as the fish suddenly disappeared from the Ravi during the spawning period.
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  • 154
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    Notes: Between December 10th and January 24th, using red, green, and white electric lights at equal intensities of about 1.7 foot-candles, sixty-nine males, with females, were subjected nightly to, (a) constant six- and six-and-one-quarter-hour periods of illumination; (b) periods increasing gradually from one-quarter to six and one-quarter hours; (c) no added light (controls), in a basement room lighted by day from three large windows. Relative heat intensities reaching the birds were: for white, 1; for green, 2.5; for red, 10.Birds were killed for testis study at 5, 12, 16, 22, and 23 days.Refractory period was shorter, and modification of spermatogenic activity much greater, under a than under b types of treatment, as compared with controls. Effects were also more consistent.Descending order of testis activity induced at all stages was red, white, control, green, under both a and b.Effects on testis activity are not proportional to heat intensity of incident light, but depend on wave length, since green effect is not intermediate between those of white and red, as its heat intensity is. Green inhibited germ-cell activity even in birds already at normal midwinter minimal condition.Constant six-hour red-light treatments, of this intensity, induced flrst appearance of metamorphosing sperms in twenty-three days in midwinter.Apparatus and mode of light regulation and measurement are described.
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  • 155
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    Journal of Morphology 52 (1931), S. 535-563 
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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 cell division in the chick embryo has revealed in striated muscle and in the early stages of all the principal tissues and organs a process, followed by the greater percentage of the dividing nuclei, which resembles amitosis, but is undoubtedly a highly modified form of mitosis. This process is designated ‘modified mitosis’. The belief that this is essentially mitotic rests upon the fact that a number of discrete bodies may be distinguished in the one or two chromatin masses of each nucleus. These masses, or ‘mulberries’, might easily be mistaken for nucleoli or karyosomes were it not that they exhibit division by elongation and constriction. These structures probably represent masses of minute and closely clumped chromosomes in somatic number dividing in a qualitative and a quantitative fashion. As additional evidence there are present between the dividing mulberries exceedingly fine fibers which possibly represent an attempt at spindle fibers. Neither centrosomes nor asters are present, but since, if present, they would have to be of the intranuclear variety (the nuclear membrane never disintegrating) their absence is immaterial. The nucleus divides not by constriction, but by the formation of a nuclear plate. This process of modified mitosis is probably a device which favors the speed of nuclear proliferation necessary to such rapidly growing tissues.
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  • 156
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    Journal of Morphology 53 (1932), S. 1-21 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Eggs of Melanoplus differentialis, a grasshopper, secured immediately after they had been laid, were placed in a water bath kept at 25°C, and allowed to develop for definite periods. After fixation, the embryos were dissected out of the eggs and drawn. Large numbers of eggs were examined in order to determine the degree of variation under specific conditions. For the stages following revolution, eggs were used in which ‘hibernation’ had been prevented by exposure to low temperatures.
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  • 157
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    Notes: The Golgi bodies of the nerve cells of the grasshopper are discrete elements composed of an osmiophilic cortex and an osmiophobic medulla. When seen in face, they appear ring-like, semicircular, or crescentic. The osmiophilic portion is interpreted as the homologue of the classical Golgi apparatus and may under certain conditions be dissolved away, leaving clear spaces homologous to the canalicular apparatus (negative image of Golgi apparatus). When the osmiophilic portion is dissolved, the osmiophobic portion remains as a definite structure which apparently has no homologue in the classical Golgi apparatus. The mitochondria are granular, rod-like, or filamentous and show no transformation into Golgi bodies. Neutral-red bodies (‘vacuome’) of two kinds have been observed, neither of which is a constant preformed structure or has any relationship to the Golgi bodies. Prolongations of the capsule (trophospongium?) of the nerve cell penetrate into the cell approximately one-third the distance to the nucleus. These are interpreted as supportive rather than nutritive in function. A basket-like net of neurofibrillae surrounds the nucleus. It is suggested that the networks described as Golgi apparatus in certain invertebrate nerve cells may really consist of these neurofibrillae.The conclusion of Parat that Golgi material consists either of mitochondria or ‘vacuome’ is rejected. The idea that all structures in the living cell which stain with neutral red (‘vacuome’) are homologous is also rejected.
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  • 158
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    Notes: Part of the nutriment of metamorphosing glochidia is supplied by the cellular host tissue, bitten by the larvae during attachment. Some of this is taken up piecemeal by the mantle cells and digested intracellularly. The coarse granules that first pack the mantle cells are apparently the precursors of a digestive secretion, some of which escapes into the mantle cavity. Here it also causes the prompt dissolution of additional utilizable host tissue.Another source of nutriment is furnished by the provisional larval adductor muscle which undergoes degenerative changes in situ, then fragments, and finally is carried away bit by bit by amoeboid cells. These turn over their muscle content to the larval mantle, where the particles are further reduced beyond recognition. The mantle remnant itself is finally sacrificed and doubtless becomes an additional source of nutriment.The gut serves as an organ of nutrition throughout the last two-thirds of the parasitic period. It appears to admit and digest pieces of the adductor muscle and certain unidentified particulate matter. In addition, the gut, like the definitive mantle and other organs, doubtless absorbs tissue transudate from the host.Special vascularization of the host tissue to facilitate the passage of nutriment from host to parasite does not occur, yet there is no reason to doubt that an appreciable part of the larval nutrition results from transuding tissue juices.
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  • 159
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    Notes: A study was made of the development of the suprarenal gland of the chick with reference to the following points: 1) Topographical relationship of the sympathetic cell masses to the cortical cords, and to the sympathetic nervous system. 2) Cytological differentiation of the sympathetic cells.The migrating indifferent sympathetic cells, although becoming generally distributed over the medial surface of the cortical ridge, form a series of more prominent aggregations at certain definite loci. These aggregations are the rudiments of two longitudinal ganglionic chains, which develop from the sixth to the seventh day. Around and between the ganglionic rudiments the indifferent cell groups become penetrated by sympathetic fibers from the ganglionic rudiments as well as by fibers of sympathoblasts which develop from indifferent cells of the sympathetic-chromaffine complex. At the same time multipolar sympathetic cells lying between the cortical cords and processes to the tracts developing between the ganglia on the surface of the cortical ridge.Differentiation of ‘chromaffine cells’ from indifferent cells of the aggregations begins during the eighth day, after a profuse innervation of the rudiments has been established. Differentiation is evidenced by the appearance of cytoplasmic granules, and by the appearance of the ‘chromaffine reaction.’ The possible bearing of the innervation of the indifferent cell aggregations upon their differentiation and upon their penetration of the cortical bodies is discussed.
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    Journal of Morphology 56 (1934), S. 621-635 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 161
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    Notes: Observations of earlier workers concerning the limited region from which anterior regeneration will occur in Tubifex and the reduced number of segments formed were confirmed in control worms used in these experiments. Only three anterior segments are replaced when as many as twelve are removed. Regeneration is completed within 18 days.Removal of anterior segments from worms that have received 9000 (r) units exposure to x-rays is not followed by regeneration. The wound heals rapidly and worms have been kept in laboratory 70 days without further change. Longitudinal sect ons of injured ends show that the epidermis and muscle layers extend across the wound surface to completely close the body cavity. The intestine retracts slightly and heals to form a blind tube. No mitotic figures appear in cells of this region and there is no evidence of regeneration.In control worms material for formation of the cerebral ganglia and new epidermis arises by proliferation of epidermal cells. The new pharynx arises from the region of the old intestine adjacent to the wound surface. The muscle layers of the body wall and pharynx in new segments are apparently formed by migration of cells from the old muscle elements about the margin of the wound area. No neoblasts were observed in anterior migration or in the process of formation upon adjacent septa in any of the worms.
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  • 162
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    Journal of Morphology 54 (1933) 
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  • 163
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    Journal of Morphology 54 (1933), S. 429-449 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: The rudimentary copulatory organ of chickens was first observed as a phallic knob in 6-day embryos. This phallic knob enlarged similarly in both male and female embryos up to the twelfth day: from the twelfth to the seventeenth day it was distinguished by a large process in the males and a diminishing process in the females. Further differentiation took place from the eighteenth to the twenty-first days: some females lacked the porcess, others retained a smaller process than that of the male. As growth advance, fewer females retained the process until at 12 weeks of age it had entirely disappeared. The process was found in all males and showed no retrogression, whereas the few capons examined lacked it. A ridge-shaped ‘pseudo’ process developed at about 1 week in some females and was present up to 3 weeks of age. Histologically and embryologically, the process was seen to possess some characteristics of a penis. The cloacal method of sex determination might be used with an average maximum accuracy of about 90 per cent in living day-old chicks.
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    Journal of Morphology 54 (1933), S. 521-547 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sex cycles of a chimpanzee were studied for 18 months, during which the animal matured, menstruated four times, conceived, and delivered.Pronounced swelling of the ano-genital region appeared periodically prior to the first menstruation. During menstrual cycles the swelling endured during most of the period between flows. Genital swelling was always accompanied by estrus; copulation and insemination never occurred during its absence.The animal was alert and active when in estrus, demonstrated non-sexual affection for the male just prior to the flow, and appeared to be physically distressed during the first days of each flow.There were periodic weight changes coordinated with the animal's menstrual cycles.During pregnancy menstruation ceased, but genital swelling, with accompanying sexual receptivity, continued in irregular cycles.Cyclic changes in the desquamation of the vaginal epithelium occurred during menstrual cycles, were absent during pregnancy.The gestation period was approximately 246 days. At death from puerperal sepsis, 15 days after delivery, the ovaries were in a restin stage, one of them bearing a degenerating corpus luteum.The evidence given indicates that sex-skin swelling and estrus are similarly controlled, but may occur independently of menstruation, cornification of the vaginal epithelium, or ovulation.
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    Journal of Morphology 55 (1933), S. 1-13 
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    Notes: The molluscan genus Indoplanorbis is shown to differ markedly from all other members of the family Planorbidae in the generative complex, the vas deferens being encased in a long, flexible tube in which it is freely movable. The preputium of the male complex is shown to be completely evertible from the male opening and to act as a male copulatory organ. The presence of a single, heavy penial retractor innervated by an equally strong nerve is indicated. Comparisons are made with the genitalia of the European Coretus and the American Helisoma showing fundamental differences in the generative apparatus of the three groups. Indoplanorbis is most closely related to Coretus, the vas deferens of that group being also encased in a tube. Helisoma differs from both of these genera, the vas deferens not being encased in a tube and is of the same diameter throughout its length.
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    Journal of Morphology 55 (1933), S. 119-129 
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    Notes: The vascular channels and sinuses of this trematode contain three varieties of cells: eosinophilic granulocytes, primitive hemocytoblasts (‘amebocytes’), and modified hemocytoblasts. The latter suggest a specialized blood corpuscle, but represent apparently only a stage in the dissolution of intravascular hemocytoblasts. These ‘corpuscles’ have the form of flattened lenticular discs, approximately 12 μ in diameter. The eosinophils differentiate extravascularly from hemocytoblasts. The hemocytoblasts are in part free parenchymal cells, in part they arise from a bilaterally paired ‘lymphogenous organ’ or ‘blood island’ associated with the lateral vascular channels at the level where the ceca diverge from the esophagus.
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    Journal of Morphology 19 (1908) 
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    Journal of Morphology 19 (1908), S. 369-438 
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    Journal of Morphology 19 (1908) 
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    Journal of Morphology 19 (1908), S. 497-510 
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    Journal of Morphology 19 (1908), S. 561-631 
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    Journal of Morphology 20 (1909), S. 549-628 
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    Journal of Morphology 19 (1908), S. 439-468 
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    Journal of Morphology 19 (1908), S. 541-560 
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    Journal of Morphology 49 (1930), S. 45-137 
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    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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    Journal of Morphology 50 (1930), S. 393-411 
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    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 53 (1932) 
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    Notes: Nyctotherus cordiformis and Opalinids infesting Rana pipiens were studied by microincineration and in stained control sections. A marked difference in concentration and distribution of mineral salts was noted within saprozoic and holozoic organisms. The endoplasm in the saprozoic protozoa was free from inorganic residue except for the ‘vegetative’ granules; the protoplasm of the holozoic infusorians consisted of a fine network of mineral salts. Detailed examinations suggested that the qualitative and quantitative differences might be correlated with diffusion of digestible material through the cuticle. The inorganic residue of the walls of vacuoles was relatively rich in iron.
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  • 181
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    Journal of Morphology 54 (1933), S. 451-457 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Recent and fossil fishes may be divided into groups having both pectoral and pelvic fins, pectorals only, pelvics only, or with a second pair of fins located anteriorly and seemingly not homologous with pelvics. In some groups the pelvics are located near the cloaca, with an extensive hiatus between the pectoral and pelvic neuromeres; other groups are of an intermediate character, while in a third group the second pair of fins appears to have no relationship to the pelvics. The character of the innervation indicates that they could hardly have been derived from the latter, and the few nerves, consecutive with the brachial plexus, which supply them suggest origin from the posterior elements of the dermal series, the anterior of which became the pectoral fins. Instances even occur (Polynemus) in which a third pair of appendages has been derived from the original pectoral complex.
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  • 182
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: The authors are preparing a table for the normal developments of the guinea-pig. This paper deals with the external form and the development of the external characteristics of guinea-pigs between 21 days and 35 days, copulation age. About one hundred embryos were used from thirty-six litters.Length and weight are good criteria for determining age, although there is some variation. The flexures, the disappearance of the tail, the development of hair follicles at specific locations, the degree of development of the mouth and external ear are better criteria for the determination of age.At 27 days there is a sudden increase in both weight and length. This increase is rather uniform from this period until the end of 35 days. At this time the embryo has the appearance of a newborn guinea-pig.
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  • 183
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    Notes: Basophiilic granule cells which occur in vast number in the connective tissue throughout all regions of the alimentary canal of sockeye salmon and speckled trout are interpreted as histogenous mast cells. Their occurrence in several other species is noted. None could be found in blood or in any other organs. Their development from mesenchymal cells is described (speckled trout). Their function or possible relationship to functional conditions of the tract could not be determined. Experiments showed the granules to be quickly destroyed by acids and bases but not by water in the fresh condition, but they were extremely stable structures after Helly fixation. In living cells, the granules are probably fluid, and consist of proteins. There was no indication of the granules being composed of mucin, or of the cells being degenerated forms. The granules are basophilic at all times.
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  • 184
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    Journal of Morphology 55 (1933), S. 81-118 
    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 interatrial septum and the relation of the sinus venosus and sino-atrial valves to the interatrial septum was followed in chick hearts ranging from 50 hours of incubation to the adult. The following singificant facts were established. The interatrial septum first appears at about 50 to 55 hours of incubation. It fuses with the endocardial cushions of the atrio-ventricular canal, typically in the last quarter of the fifth day. Secondary perforations appear in the septum at the time of closure of the interatrial foramen primum. These are retained until hatching, although they may persist in the adult heart. The sinus venosus, a sinus septum, and the sino-atrial valves are retained as definite structures in the adult fowl heart. The pulmonary vein and the left precava as they enter the heart form a prominent addition to the inter-atrial septum proper which I have designated as the pars cavo-pulmonalis. The pulmonary orifice in the left atrium is provided with an extensive flap-like valve. A prominent limbus of Vieussens is present in the right atrium. A well-developed median muscular arch overlies the interatrial septum and a pair of lateral muoscular arches extend over the atria. Their position would seem to be significant in the closing septal perforations during atrial systole.
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  • 185
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    Notes: The alignment and condition of mitochondria in the epithelial cells indicate that secretion is apparently the chief function of the midgut and the attached caeca. In view of the response of these cells to vital dyes, and to various fixatives, other cell structures-particularly vacuoles-are uncertain evidence of cell activities. Many structures visible by means of vital dyes indicate changes in the permeability of the cell membrane, and subsequently in the cytoplasm. Hence, they are artifacts, just as truly as those found in fixed tissue.
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  • 186
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    Journal of Morphology 55 (1933), S. 137-149 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mid-dorsal protective hair-shafts from forty-five species of Soricidae were studied with the object of investigating the relation between the differences in certain microscopic structural elements and the diameters of the shafts in which they were developed, and the possible occurrence of specific characters in these elements. In comparing like portions of like hair-shafts, it was found that scale- and medulla-forms were related (with slight variations within their form-groups) to the diameters of the hair-shafts in which they were developed. It is possible that further study of these slight variations may show them to be associated with the species bearing the hair.
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  • 187
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    Journal of Morphology 55 (1933) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 188
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    Journal of Morphology 55 (1933), S. 253-263 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A survey of biological literature of the present reveals a tendency to turn to the study of the living cells and tissues. This tendency is indicated by the use of microdissection, ultraviolet microscopes, transparent chambers in rabbits' ears, growing nerve cells and fibers in tailfins of amphibian larvae, and by intravitam technic on insect germ cells. The division stages of the germ cells of Anasa tristis which were carefully studied and drawn thirty-odd years ago are now shown by actual unretouched photomicrographs. These photomicrographs confirm the drawings in many points and show other structures such as mitochondria even more clearly than the drawings do. An account of a peculiarly shaped spermatozoon which has not been described heretofore in the literature is added. The question of the great variations of shapes of spermatozoa is discussed. The advantages of the use of methods for studying living cells, especially of intravitam technic, is emphasized.
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  • 189
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    Journal of Morphology 55 (1934) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 190
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    Journal of Morphology 52 (1931), S. 565-592 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Serial sections of seven embryos were examined, in four of which the chondrocrania were reconstructed. Parachordals appear as independent precartilages on each side of the notochord in the otic region. Later chondrification occurs, and they fuse with the notochord. Orbitals and trabeculae appear as independent precartilages; later, as cartilages they fuse with the basal plate and with each other, forming the cranial wall between the orbital cavity and brain. An apparent shifting posteriorly of the bases of the fifth, seventh, and eighth cranial nerves, in respect to the anterior end of the notochord and to the otic vesicles, occurs between the 10-mm. and the 60-mm. stages. The otic vesicles, proportionately small in the 10-mm. stage, reach their relatively largest size in the 19-mm. embryo. The floors of the otic capsules begin as lateral extensions of the basal plate at the 25-mm. stage, and from these anlagen chondrifications extend, forming the anterior and posuerior cupolas. Most of the tegmen cranii forms by chondrifications that approach the median plane from each side. It is practically complete in the 60-mm. embryo. The cervical neural arches also contribute in forming the tegmen cranii and the occipital region. The ventrally recurved end of the notochord of the 10-mm. stage persists through the 60-mm. embryo.
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  • 191
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    Journal of Morphology 53 (1932), S. 133-187 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study deals with the development of the duck embryo from the unincubated blastoderm to the 1-to-3-somite stage. In the unincubated stage the thickened posterior germ wall is the most active region mitotically, contributing cells to complete the entodermal layer. The slightly thickened ectoderm of the posterior half of the pellucid area is the precursor of the embryonic shield. During incubation this ectoderm increases in height, forming the embryonic shield. The primitive streak arises in the posterior part of the shield, where tall ectodermal cells in the midline become several-layered and proliferate cells from their ventral surface which migrate laterally, becoming mesoderm. At first short and broad, the streak becomes longer and narrower until it attains its definitive stage.The greatest proliferation of ectodermal cells occurs always at the anterior end of the streak of all stages, forming at the definitive stage a definite thickening-Hensen's node. Proliferation diminishes posteriorly along the streak.The number and orientation of mitotic figures indicate cell movements as follows: Prestreak stages-ectodermal cells migrate from posterior part of shield toward midline, thence forward in midline; early streak stages-anterior movement in streak and to sides of streak, and lateromedial movement from sides toward middle of streak; definitive streak stages-postero-anterior and lateromedial migration of cells.The embryonic axis, of prestreak and streak stages, lies approximately at right angles to the egg axis in slightly over 50 per cent of the cases.
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  • 192
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    Topics: Biology , Medicine
    Notes: The parietal cells of the salivary glands of the grasshopper are large and roughly spherical or sometimes pyramidal in form, scattered for the most part singly among the zymogenic cells of the lobules. They possess a magnificent system of intracellular canaliculi into which their secretions are directly emptied and conveyed to the exterior of the cell. These intracellular canaliculi are strikingly impregnated with osmic-acid methods (Nassonov, Mann-Kopsch) in a manner comparable to the contractile vacuole of Paramecium as described by Nassonov. However, in addition to the impregnated system of intracellular canaliculi, Golgi bodies are found evenly distributed throughout the cell in the form of crescents, semicircles, or ring-like structures typical of insect tissue.Inasmuch as a direct homology between the intracellular canaliculi and the contractile vacuole of Paramecium, both from the point of view of morphology and physiology, seems justified, we question the inference drawn by Nassonov that the impregnated walls of the contractile vacuole in Paramecium actually represent Golgi material. Deduction is made from these and previous studies that the magnificent network of ‘vacuome-Golgi apparatus’ described by Parat and Painlevé ('24) in the salivary glands of Chironomus larvae is nothing more or less than intracellular secretory canaliculi.Mitochondria in the parietal cells are abundant in the characteristic form of short rods and filaments. No evidence of a direct transformation of mitochondria into Golgi bodies. as held by Parat, was observed. Golgi bodies and mitochondria show no marked topographical relationship to the intracellular secretory canaliculi.
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  • 193
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    Journal of Morphology 53 (1932), S. 327-343 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study is based on a wax model reconstructed from serial sections stained with basic fuchsin and picro-indigo-carmine. It shows: 1) that the columna ethmoidalis and planum basale are chondrified at this stage; 2) that a cartilaginous antorbital process is present; 3) that the stapedial plate is cut out from the wall of the otic capsule; 4) that the so-called crista trabecularis is an independent element homologous with the sphenolateralis of the Anura; 5) that the fourth visceral arch is not present and that the fifth is still in the precartilaginous stage; and, 7) that there is no evidence that a pro-occipital vertebra is formed.
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  • 194
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    Topics: Biology , Medicine
    Notes: Opalinids from the rectum of Rana pipiens were isolated in large numbers and fixed in a mixture of nine parts of absolute alcohol and one part of neutral formalin. These were embedded in paraffin and incinerated according to the technique of Policard. Examination of the preparations by dark-field illumination showed that the micro-incinerated protozoa retained their distinctive morphological and cytological characters, for the mineral ash had the same topographical distribution as the cell inclusions in the control stained preparations.The coarse vegetative granules of the cytoplasm were preserved as distinct masses of ash which corresponded exactly to these bodies in the control preparations. The structure of the myonemata and the cilia was perfectly preserved. The chromatin material of the nucleus, more or less abundant, left little or no ash, which is quite in contrast to the findings of Scott with regard to amphibian and mammalian nuclei.
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  • 195
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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 blood of Batrachoseps one part of the erythrocytes is formed inside the nucleus of plasmocytes as a result of the metamorphosis of chromatin substance. When erythrocytes are completely formed, they separate themselves from the plasmocytes.Disappearance of the hemoglobin of erythrocytes with pigment metamorphosis is visible in the drawings.When the disappearance of hemoglobin with pigment metamorphosis takes place, the color of the hemoglobin cytoplasm frequently becomes very pale. The hemoglobin cytoplasm may vanish also without pigment metamorphosis in such a way that the whole cell (nucleus and cytoplasm) swells, and the cytoplasm becomes paler, and finally only a pale shadow remains which is rather difficult to distinguish. The author has noticed in the blood of Batrachoseps, besides extrusion of small nuclei from the erythrocytes, also a particular way in which chromatin substance is eliminated from the cell. While the cell and the nucleus become pear-shaped, the nucleus moves toward the periphery, touching the surface of the cell with its funnel-shaped narrow side. From this narrow side the chromatin substance flows out in the form of a band stained red, according to Romanowsky.
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  • 196
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    Journal of Morphology 56 (1934), S. 125-155 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The chromosomes of D. melanogaster have been followed through the entire cycle of mitosis in ganglion cells. Primary constrictions exist at about the middle of the second and third chromosomes, at a sub-median position in the Y, at a sub-terminal in the X, and probably also at a sub-terminal position in the fourth chromosome. Secondary constrictions, in addition to those reported by Bridges, are sub-terminal in the arms of the second and third chromosomes. A pronounced sub-median secondary constriction in the left limb of the second chromosome offers a criterion for distinguishing between the second and third chromosomes, and between right and left arms of the second chromosome. The proximal secondary constriction in the X-chromosome and that in the short arm of the Y are associated with the normal development of the nucleolus. Anaphase chromosomes are longitudinally double, the split following the turns of the chromonemata. Metaphase and anaphase chromosomes are essentially isodiametric from end to end, except at the constrictions or indentures. Somatic pairing of chromosomes reaches its maximum expression during late prophases, both in male and female ganglion cells. The four chromatids of the tightly appressed homologues open out in two planes giving distinct chiasma-like configurations. Separation of the paired chromosomes is completed in late prophase, so that at metaphase the homologous chromosomes are not in contact.
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  • 197
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytology of corpora lutea of non-pregnant ewes is described with reference to the origin, structure, fate, and function of these organs. The lutein cells, characteristic of corpora lutea, are derived from the cells of the stratum granulosum of the Graafian follicle; connective-tissue cells, embryonic cells, and non-striated muscle cells, from the theca interna; and erythrocytes, leucocytes, and histiocytes, from the blood stream. The lutein cells undergo changes in size, nuclear structure, and cytoplasmic inclusions correlated with the period in the estrous cycle and disappear during retrogression. Although secretory products have not been identified, a secretory function is postulated on the basis of the structure of the cell.
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  • 198
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    Journal of Morphology 56 (1934), S. 231-241 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The three species of Trichonympha found in Zootermopsis angusticollis were studied by micro-incineration, by control sections, and by Macallum's methods for iron and calcium. The mineral ash is concentrated in the neuromotor system, chromatin, nuclear membrane, the posterior end where ingestion takes place, and in cytoplasmic granules. Micro-incineration and Macallum's Prussian blue method reveal iron in the chromatin alone; Macallum's haematoxylin gives a positive test for iron in the chromatin, rostrum, neuromotor fibrils, etc. It probably is not as specific as the other methods. The two staining methods give negative tests for iron except after acid hydrolysis. Calcium is present in the chromatin, neuromotor system, posterior region of the body, and in many endoplasmic granules. The localization of calcium is correlated with the localization of normally gelated regions.
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  • 199
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    Journal of Morphology 56 (1934) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 200
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    Journal of Morphology 56 (1934), S. 213-229 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The conspicuous intracellular fibers (figures of Eberth) which are present in the basal epidermal cells of Rana pipiens and Rana clamitans tadpoles are thought to be connective tissue branches from the corium. They are not believed to represent fused mitochondria as concluded by Saguchi ('13). Their probable function is to furnish support to the basal epidermal cells and to strengthen the connection of the epithelial layer to the corium.It is believed that fully developed tadpole skin, before the period of metamorphosis has begun, consists of only two layers of cells, although there may appear to be more. Each of these layers is believed to be self-maintaining by mitotic division within the individual layer. The basal layer apparently does not furnish cells to the outer layer, nor was any evidence found that the outer layer is sloughed during the larval period.
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