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  • Life and Medical Sciences  (2,612)
  • AERODYNAMICS  (2,113)
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  • 1975-1979  (4,702)
  • 1935-1939  (587)
  • 1925-1929  (199)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 40 (1925) 
    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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  • 2
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 40 (1925), S. 111-167 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Microscopic examination of both living and stained forms indicates that the so-called ‘multivacuolate’ and ‘amicronucleate races of Paramecium caudatum’ belong to the species Paramecium multimicronucleata. The published accounts of the morphology and cultural characteristics of the various forms are compared and provide additional evidence. A more complete description is given, including distinctive characters previously omitted.The conjugation process of P. multimicronucleata in general resembles that of P. caudatum, most of the differences being due to the presence of four micronuclei instead of one. These each divide twice with characteristic figures, twelve of the sixteen daughter nuclei then degenerating. One of the remaining four splits to form a single pair of functional pronuclei in each cell. The two migratory pronuclei interchange as in P. caudatum. The synkaryon divides three times, and probably seven of these nuclei degenerate. The remaining one apparently undergoes two divisions. In most cases by six to eight hours after the conjugants separate two micronuclei of the four thus produced form enlarged macronuclear anlagen, the other two remaining as micronuclei. Each anlage divides within the next two or four hours, producing four macronuclear and four micronuclear analagen. Two fissions, each preceded by a division of the micronuclei, restore vegetative conditions.The process described above is compared with conjugation in P. bursaria, P. caudatum, and P. putrinum.
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  • 3
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 40 (1925), S. 261-297 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The parasynaptic union of chromosomes associated with the formation of a karyosphere is demonstrated in the spermatocytes of Phanaeus.The twelve V-shaped leptotene threads are polarized with their apices embedded in one plasmosome-like body, their distal ends in another (primary and secondary caps, respectively), and undergo a conjugation of the parasynaptic type. The distal ends of the chromosomes are freed from their attachment in the secondary cap. The six pachytene loops retain their polarized configuration.The basichromatin of the pachytene chromosomes appears ultimately to be withdrawn to form the karyosphere comprising six chromatic bodies within an oxychromatic «plasmosome,» the latter probably derived from the primary cap. The two caps are believed to arise from the chromosomes. The primary cap apparently becomes incorporated again in the chromosomes; the secondary cap, together with linin remnants of the pachytene chromosomes, disintegrates in the nucleus as residual chromatin.In the dissolution of the karyosphere six ring-shaped tetrads emerge arranged in a temporarily connected chain, giving under certain conditions, the misleading impression of twelve components arranged end to end. The entire content of the karyosphere appears to be employed in the formation of the chromosomes; no visible plasmosome remains.
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  • 4
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 40 (1925), S. 417-459 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development and cytology of cartilage and bone in the limbs from the fifty-second hour of incubation to the first day after hatching are described.The chief points of interest arising from this study are: (1) Chondroblasts when liberated during cartilage resorption die and disintegrate. (2) All the long bones possess structures which, though not undergoing independent ossification, are homologous with the mammalian epiphyses. (3) Endochondral ossification occurs only in the epiphyses and ends of the diaphyses. (4) The marrow cavity contains multinucleated giant cells which appear to be formed by the fusion of degenerating cells.
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  • 5
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The blood of Perophora viridis is found to contain six types of cells: (1) Green cells, which have green-colored fatty bodies embedded in clear cytoplasm. (2) Orange cells, with orange-colored bodies of unknown composition in the cytoplasm. (3) Colorless berry-like cells, with fluid-filled vesicles in the cytoplasm. (4) Granular amoeboid cells. (5) Compartmental amoeboid cells, which have box-like vacuoles containing brownian granules of a fatty substance. (6) Vesicular, signet-ring type of cell having a single large vacuole. The cytological structure of these cells and their reaction to various dyes are described.An effort has been made to homologize the types of cells found in the blood of other ascidians with those found in Perophora.It is concluded that the variety of colors found in the cells of ascidian blood is due to the varying chemical states of the vanadium-containing chromogen present in the cells.
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  • 6
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 41 (1926), S. 441-546 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Embryological study of bullfrog tadpoles collected from various parts of the United States has shown the existence of local races which differ markedly in regard to the time of occurrence and character of the developmental processes involved in the formation of the definitive testis of the male individuals. Those races in which the gonads of the two sexes are easily distinguished in early larval stages are called differentiated. Other local races show a peculiar gonadic development chiefly affecting the males, the definitive testis sometimes not appearing until near the end of the second year of larval life. Such races are called undifferentiated, because the morphological features of the definitive testes are not established until late. The larvae first develop a peculiar gonad (progonad) which later degenerates and is replaced by the definitive testis. All male animals of the undifferentiated strains exhibit the gonad cycle.The progonad varies among the local frog races in regard to the length of persistence and degree of differentiation attained before undergoing degeneration. Its germ cells may exhibit a typical male maturation cycle ending in degeneration, or the cells may differentiate along both male and female lines or remain sexually neutral.The development and differentiation of the progonad in the various races are described and a detailed account given of the origin of the definitive testis. The problems of sex differentiation and continuity of the Keimbahn in anurans are discussed.
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  • 7
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926) 
    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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  • 8
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926), S. 111-141 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Disintegration in killing agents was studied throughout development. In the unfertilized egg and cleavage stages the death gradient runs from animal to vegetal pole. In the late blastula stage the future dorsal surface and future point of gastrulation show heightened susceptibility. The gastrula has a gradient from anterior to posterior end along its dorsal surface, with a slight reverse gradient around the blastopore; lateral and ventral regions are least susceptible.Before and after the appearance of the neural groove, the dorsal surface shows increased susceptibility with gradient in it from anterior to posterior end. The neural tube is highly susceptible, with a death gradient from anterior to posterior end and a slight reverse gradient at its posterior end.During late stages and in the larva the double gradient is present; death begins at the two ends and progresses backward from head, forward from anus; from the former most rapidly. The least susceptible place is near the posterior end. The posterior reverse gradient is less developed in the lamprey than in other vertebrate embryos, due, probably, to its lack of a tail bud.Assuming that death differences indicate differences in rate of activity, it appears that such differences in activity may be causes and not results of developmental processes, for the development of certain parts (dorsal surface, blastopore, central nervous system) is indicated by heightened activity before it is evident morphologically.
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  • 9
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926), S. 371-439 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The prochordal plate in the chick is a thickening of the entoderm in the anterior part of the area pellucida. It consists at first of several layers of yolk-charged cells, which finally lose their yolk and form a thin layer of entoderm.The prechordal plate (an area of mesodermal proliferation immediately anterior to the notochord) arises immediately anterior to the primitive streak (and head process when the latter appears) in a part of the region once occupied by the prochordal plate. Later the prechordal plate comes to lie upon the dorsal wall of the foregut.The premandibular cavities arise in condensations of the prechordal mesoderm. The cavities seem to appear during the rapid expansion of the prechordal mesoderm which occurs in response to a release from constraint imposed by surrounding structures. They are connected with one another across the midline by a usually solid bridge of mesoderm.Later, the cavities are replaced by a mesodermal condensation which serves as a mold, on the surface of which the oculomotor muscles appear, arising before the disappearance of the premandibular head cavities.Differences in the relations of notochord and hypophysis in the chick and robin may be explained by an analysis of the growth of the two forms. The analysis furnishes a basis for understanding the relations of the anterior end of the notochord in the mammal.
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  • 10
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1926) 
    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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  • 11
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1926), S. 81-103 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Paramecium trichium varies from 50 μ to 105 μ long with most individuals between 80 μ and 90 μ. The width varies from one-third to one-half the length. It is somewhat depressed dorsoventrally. The broad buccal groove extends from the anterior left border diagonally across the ventral surface to the mouth, which is usually slightly anterior to the middle and to the right side of the median line. The mouth leads into a relatively long cytopharynx containing an undulating membrane. The cytopyge is subterminal and the small caudal tuft of longer cilia is subapical. The plastic ectosarc contains numerous trichocysts. A contractile vacuole apparatus occurs near either end. Each is deeply located and stains more intensely than surrounding protoplasm. In life there appear to be two alternately contracting vacuoles with smaller ones adjacent. Contractions are from fifteen to twenty-five per minute. The macronucleus is medium in size and the single micronucleus is of the ‘caudatum’ type.Binary fission appears to be initiated by a metaphase-like condition of the micronucleus. This is followed by great enlargement and the eventual separation of the chromatin threads into two anaphase groups. The metaphase thus appears to precede the changes which correspond to a prophase in other cases. During division of the body, the two old contractile vacuoles persist as the posterior ones for the daughters, new anterior ones being developed.
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  • 12
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1927) 
    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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  • 13
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1927), S. 299-345 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The chondriosomes are first recognizable as two clusters in contact with the nuclear wall. Beneath each cluster lies a chromosome. This relationship is constant and indicates that these two chromosomes play a part in the growth and development of the chondriosomes. The two masses fuse and the single mass grows considerably during the early growth period. Later it breaks up into a number of threads which become rings in the late growth period. The rings fuse into the large nebenkern which plays the usual rôle in the formation of the tail.The Golgi material is first seen outside of the chondriosomal cap. Early in the growth period, it breaks up into Golgi bodies which remain distributed in the cytoplasm during the growth period and spermatocyte divisions. About the midgrowth period a large number of spheres suddenly arise. Since they later fuse to form the idiosome, they are called the proidiosomal spheres. These spheres, which may originate in the Golgi bodies, remain scattered in the cytoplasm during the growth period and spermatocyte divisions. In the spermatid the Golgi bodies collect about the idiosome to form the acroblast. The Golgi remnants pass into the cytoplasm of the tail, while the acrosome elongates into a tail-like structure at the anterior end.The centriole was followed with unbroken continuity from the midgrowth period into the middle-piece of the sperm.
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  • 14
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1927), S. 521-546 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The literature on the general subject of freezing and survival both in plants and in animals is briefly reviewed and a bibliography given. Insects representing three ecological groups, (1) the oak borers - exposed to temperature extremes normally; (2) stored-products insects representing supposedly a tropical or subtropical group, and, (3) aquatic insects never exposed to temperatures lower than 0°C., were chosen for this study. Determinations of the freezing and undercooling points were made during the yearly cycle.Both the stored-products insects and the aquatic insects studied showed no periodicity in freezing or undercooling. The oak borers showed marked periodicity. The freezing-point varies directly with the moisture content. Cold-hardiness was produced experimentally by, (1) exposure of insects to low temperatures and, (2) by dehydration. Loss of cold-hardiness was produced experimentally by combinations of high temperature, food, and high relative humidity. The freezing-point ordinarily found corresponds with that of the blood. Repeated freezings of the same insect or tissue showed no hysteresis. There exists in certain insects a secondary freezing-point below that ordinarily found. Oak borers in summer condition die at the first freezing-point; in fully hardened condition they die at the secondary freezingpoint.
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  • 15
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 1-20 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ant Formica exsectoides F. builds mounds with some reference to sunlight, and measurements of internal temperatures have shown them higher in upper parts of the mound, but different in different faces of the mound - all higher than the earth outside the mound.Inside temperatures are not constant; they are due to the sunshine. The mound is so fabricated that the internal temperatures are conserved during the night. The ants make use of the differential internal temperatures for rearing broods.Some mounds show bilateral symmetry dependent upon sun exposure.Measurements of rate of running of these ants show a falling off with lower temperatures, and possibly this is one factor in the smaller development of northerly aspects of these mounds.
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  • 16
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    Journal of Morphology 44 (1927), S. 313-339 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The rates of oxygen consumption of single pupae of blowflies (Phormia terraenovae, Phormia regina, Lucilia sericata), of the flesh fly (Sarcophaga sarracenioides Aldrich), of the Mediterranean flour moth (Ephestia kuehniella), and of the bee moth (Galleria mellonella) during metamorphosis, until emergence, have been determined. The record for each pupa, with the exception of those of blowflies, is practically continuous day and night during the period of pupal development which lasted from 140 to 300 hours, according to the species, at the temperatures used. During pupal development there is first a period of decrease in rate, which is later followed by a steady increase until a short time before emergence, when a sudden decrease occurs.The ‘oxygen curves’ of the blowfly pupae (Diptera) are quite different from those of the flour-moth and bee-moth pupae (Lepidoptera), although all are of the same general U-shaped type. There are strong indications of a specific difference in the curves of the blow-fly pupae. The flour-moth pupae curves differ slightly from those of the bee-moth pupae. During the major part of development the rates of O2 consumption of pupae of both sexes of bee moth and flour moth are about the same, but near the end of metamorphosis the females have higher rates than the males. No such sex difference appears among the dipterous pupae used.
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  • 17
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The results of the study of certain factors which affect encystment in Didinium nasutum indicate the following: Absence of food constitutes an adverse environmental condition which induces encystment in approximately 50 per cent of the didinia subjected to it, though the presence of a certain amount of food in the cell body is requisite for encystment. The prevention of encystment for 750 generations does not affect the percentage of didinia which encyst in the absence of food, and hence Didinium does not become progressively more disposed to encystment as generations pass. Conjugation does not affect the percentage of didinia which encyst in the absence of food. Metabolic by-products of Paramecium inhibit encystment to a striking degree when didinia are deprived of food in the presence of these products. Metabolic waste of Didinium markedly facilitates its encystment in the absence of food. Hay-infusion culture fluids of different ages have singularly diverse effects on the encystment of didinia in the absence of food; recently prepared infusions inhibit encystment; infusions four to six days old induce encystment in 90 to 100 per cent of the specimens, and infusions seven to fourteen days old, in approximately half of the specimens.
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  • 18
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    Journal of Morphology 44 (1927), S. 89-115 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The investigation is based upon hemal nodes of dog, man, and sheep. The material can be arranged in a regressive series leading from a typical lymph node, except for the occurrence of blood in parenchyma and sinuses, to a lymphoid structure at a late stage of involution. These structures uniformly lack lymphatics. There is no evidence of direct luminal connection between the blood-vascular supply and the sinuses. The observation that certain cervical and subcutaneous lymph nodes of the rabbit undergo a myeloid metaplasia following atrophy and disjunction of their lymphatics is used as an explanatory key of hemal nodes. According to our view, hemal nodes represent stages in the involution of transient lymph nodes. Disjunction of the lymphatics leaves the sinuses filled with entrapped lymphocytes. These differentiate into erythrocytes. These red blood cells may disintegrate and pass into solution or be removed either by giant cells or mononuclear phagocytes. Late stages in this process are represented by small irregular masses of lymphocytes, with wide sinuses practically free of blood.
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  • 19
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 20
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    Journal of Morphology 44 (1927), S. 29-87 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The anlage of the abducens musculature appears first at 24-25 somites as a condensation situated dorsal to the mandibular arch.The anlage of the superior oblique grows forward from a mesodermal condensation situated in the maxillomandibular region, termed for convenience the maxillomandibular condensation. This last consists of three parts: (1) the anlage of the superior oblique: (2) the anlage of the abducens musculature, and, (3) an intermediate region.The intermediate portion of the maxillomandibular mass forms a condensation with which the anlage of the abducens musculature fuses. Its fate is, therefore, similar to that of the so-called ‘muscle E’ of elasmobranchs, which has been described as fusing with the lateral rectus. How much muscle is formed from the intermediate condensation in the chick has not been determined.The development of the pyramidalis and quadratus nictitans muscles, derivatives of the abducens complex, is described.The premandibular head cavities are replaced by solid mesodermal condensations, on the surface of which the anlagen of the oculomotor muscles appear. The premandibular mass expands laterally and anteriorly over the bulbus, carrying the oculomotor muscles to their respective positions on the bulbus.Portions of the premandibular and maxillomandibular condensations not involved in eye-muscle formation take part in the formation of choroid and sclera.The growth shiftings of the eye muscles are analyzed. The order of their appearance is commented upon.
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  • 21
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    Journal of Morphology 44 (1927), S. 127-216 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study represents the first critical investigation on the development of the embryonic skull of the porcupine. A complete series of stages makes it possible to trace the developing chondrocranium from its first formation in precartilage to its later transformation into cartilage bone. Concurrent with this growth is the investment of the cartilaginous cranium by membrane bone.The very primitive nature of the chondrocranium offers an excellent opportunity to discuss the existing problems of the embryonic skull from a new angle. Evidence is presented in support of the assumption that the ala temporalis is the homologue of the cynodont epipterygoid. The lamina parietalis develops from a single chondrifying center, thus producing a different arrangement of parietal elements from that found in most mammals. New evidence as to the relationship of the dens epistrophei and basal plate is presented. The position of the internal carotid artery on entering the cranium is different from the condition found in most mammals and throws new light on the interpretation of surrounding structures. The presence of a structure comparable with the crista longitudinalis of Lacerta shows close affinity to the solum nasi of more primitive forms.The great specialization of the face is seen in the early and rapid growth of the membrane bones. The chondrocranium is long persistent and cartilage bone appears late in embryonic life.
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  • 22
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    Journal of Morphology 44 (1927) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 23
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    Journal of Morphology 44 (1927), S. 417-465 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Observations indicate that this Balantidium from the guinea-pig is Balantidium coli, the form found in the pig and man. The lengths and breadths of this Balantidium and the ratios of length to breadth are very close to the measurements and ratios given by McDonald for B. coli. When plotted, the body lengths of the guinea-pig parasites appear in two groups, the smaller individuals being the exconjugants. Many of these exconjugants resemble Neiva's B. caviae. The structure of the Balantidium from the guinea-pig is essentially identical with that of B. coli as given by McDonald.Fission and conjugation of this ciliate follow the general course found in a number of other ciliates. During fission the micronucleus divides and the daughter micronuclei migrate to each end of the macronucleus before the latter divides. In conjugation there are two divisions of the micronucleus, one of these nuclei dividing to form the pronuclei. Pronuclear exchange and fusion are followed by a heteropolar division of the synkaryon, resulting in the formation of the new macronuclear and micronuclear anlagen.The parasite was found in the intestinal tissue of the host. No reproductive stages were found in the cysts. New hosts are invaded through contamination of the food and drink with the cysts.
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  • 24
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: By the use of a satisfactory technique, excellently preserved spermatogenetic tissue was had both for Rattus rattus and Rattus norvegicus. The careful examination of twelve spermatogonial cells of the former species and of twenty in the latter species shows that R. rattus has forty diploid chromosomes and R. norvegicus, forty-two. A careful examination of the haploid cells of both species, both in the first and in the second spermatocyte divisions, confirms the diploid determinations.Both species have an unequal pair in the spermatogonial divisions and the finding of a similar unequal pair in the first spermatocyte division constitutes the evidence for an X-Y mechanism in each. A comparison of the morphology of the first spermatocyte tetrads in the two species reveals the presence of a large K-shaped chromosome in R. norvegicus which is not present in R. rattus. Furthermore, a comparison of the X-Y complex in both the spermatogonial and first spermatocyte divisions shows that these are morphologically different in the two species, the Y in particular being markedly dissimilar in size. A short discussion as to the bearing of these findings on the questions of the origins of the two species and their known intersterility is presented. The marked similarity of the tetrads of the black rat to those described for the mouse is noted.
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  • 25
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A technique is developed whereby the large heavily yolk-laden grasshopper egg may be sectioned for cytological study. Eggs of Chortophaga viridifasciata and Circotettix verruculatus were examined.In C. viridifasciata the structure of the late ovarian nucleus and the chromosomes in meiosis, fertilization, and early cleavage are described. In the first maturation twelve rod-shaped tetrads are found. Near the caudal end of the egg a polar body is given off, and in the second maturation division there are twelve dyads. At fertilization, twelve separated vesicles of the female pronucleus are seen scattered about a male pronucleus in which the chromosomes are in prophase.In early cleavage the chromosome numbers in the metaphase are found to differentiate the male- and female-producing eggs. In the former there are twenty-three and in the latter twenty-four chromosomes. A vesicular condition in which the chromosomes retain their boundaries in interkinesis is indicative of chromosome individuality.A comparison of the first and second maturation metaphase chromosomes of the oocyte with those of the spermatocyte shows a similar compact group on the spindle, a likeness in size seriation, and a similarity of form. They differ in that in the spermatocyte complex there are eleven tetrads and one dyad. This latter, the unpaired sex chromosome, falls among the large chromosomes.A comparison of the chromosome complex of Chortophaga viridifasciata with that of Circotettix verruculatus indicates constancy of generic differences in form, size, number, and behavior of the chromosomes.
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  • 26
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    Journal of Morphology 45 (1928), S. 233-257 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytological and histochemical evidence presented in this paper shows the following facts: (1) The mitochondria are not directly transformed into yolk. They may be concerned in its synthesis in so far as they are a factor in the interacting cytoplasmic system, but there are no visible morphological expressions of this functioning. (2) The accumulations of aequeous substances in the cytoplasm in the form of droplets stainable vitally by neutral red, ‘vacuoles,’ are the forerunners of the first yolk. During the building up of the yolk the aequeous droplets become more and more dehydrated and lose their capacity for being vitally stained. (3) These aequeous vacuoles give the impregnation results commonly ascribed to the Golgi apparatus and are interpreted as such. Special emphasis is laid on the question of the identification of the Golgi apparatus. (4) The fat arises de novo in the cell independently of the mitochondria or the vacuoles. It becomes dispersed throughout the cell among the yolk plates, and the lipoidal content of the latter increases at the end of vitellogenesis, when the fatty globules are intimately pressed in among the yolk plates. (5) At a late stage in the growth of the yolk plates there is the sudden appearance of large quantities of glycogen in the perinuclear zone and throughout the cytoplasm.
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  • 27
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    Journal of Morphology 45 (1928), S. 441-471 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The septomaxillary bone is described in the various families of the urodeles in which it occurs. Its identity as a hitherto unrecognized cartilage bone of the skull is established and its close relationship with the nasal muscles followed through the group. Its presence or absence, which is found to be another criterion for the recent classification of the urodeles as proposed by Dunn and Higgins, is correlated with the development of the accessory dilatator muscle, since it occurs only in groups where this muscle attains an appreciable size.
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  • 28
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    Journal of Morphology 45 (1928), S. 537-554 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Modifications of the gastro-intestinal tract of Nereis virens are two dorsolateral esophageal cecums, directed anteriorly and posteriorly from the point of attachment. The cecal and esophageal lumina are continuous. Each cecum is composed of acini, possessing a row of elongated cells, basement membrane, and intima. Fibro-elastic tissue is present. The elongated cells contain glycogen and fat.The hepatopancreas of Asterias vulgaris consists of two lobes in each ray, and the numerous acini empty into the bifurcated hepatopancreatic duct which leads into the pyloric stomach. The hepatic cells are columnar and contain glycogen and fat. Pancreatic cells lie in the midregion of the acini.The lobulate liver of Loligo pealii lies on the ventral surface of the duodenum. A capsular membrane envelops the organ. The acini possess basement membrane, columnar cells, and intima; their lumina anastomose, forming a common duct, which leads into the blind sac. The hepatic cells contain fat.The hepatopancreas of Melanoplus femur-rubrum consists of six cecums histologically continuous with the digestive epithelium of the pyloric stomach. Each cecum consists of simple and compound acini which empty into a duct leading to the pyloric stomach. Each acinus possesses basement membrane, columnar hepatic cells, pancreatic cells, and intima. The pancreatic cells occur in islets, usually adjacent to the basement membrane. The hepatic cells contain glycogen and fat.
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  • 29
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    Journal of Morphology 46 (1928) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 30
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    Notes: Fetuses from forty-three gravid uteruses from sows of known breeding dates, as well as from 448 uteruses with unknown breeding dates, were studied. Growth curves are given for weight and length of fetus and for weight of fetal membranes. The weight of the fetus first reaches that of the fetal membranes between the sixtieth and seventieth days of pregnancy. Degenerate fetuses were found in 3.68 per cent of the cases. They were found at all stages of gestation. Size of litter was found to decrease from 11.4 at the twentieth day to 6.8 at the 110th day. Also, the calculated per cent of ova lost up to each ten-day stage tends to increase as gestation advances. Crowding was found to be an important factor, but probably not the only factor, in causing degeneration. Genetic factors were probably responsible for part of the resorbing fetuses.In the study of the normal fetuses, significant correlations were found between fetus length and weight of fetal membranes, as well as between fetus weight and weight of fetal membranes. Lower correlations, but probably significant, were found between total distance (spacing) between fetuses in the uterus and weight of fetal membranes. Correlations between size of fetus and total distance between fetuses were very low. As in the case of the degenerates, crowding has an important relationship to size of fetus, but is probably not the only factor involved.
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    Journal of Morphology 46 (1928) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 32
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    Notes: This study deals with the seasonal distribution of protozoa (February, 1927, to February, 1928) in correlation with seasonal fluctuations of temperature, hydrogen-ion concentration, and the relative amounts of dissolved oxygen and other gases in a small fresh-water pond. Twenty-seven species of Sarcodina, thirty-one species of Mastigophora, and 109 species of Infusoria were recorded in the surface water of the pond.As found especially for Mastigophora and Infusoria, the number of species is inversely correlated with the abundance of individuals in the seasonal distribution.Higher temperatures probably accelerated the rate of reproduction, since the seasonal maxima for most of the species were recorded in warmer weather.Colonial flagellates and Zoochlorellae-bearing ciliates seemed to be favored by higher oxygen content, with a simultaneous abundance of volatile acids, especially CO2. Although hydrogen-ion concentration was limited between 6.2 and 7.05, it was probably one of the factors influencing protozoan distribution, since several species disappeared when the lowest pH was recorded. Sunlight is one of the important factors in bringing certain heliotropic protozoa to the surface.The seasonal maxima of many of the protozoa occurred during September and October, 1927, when most of the observed physical environments seemed much more favorable than in other months.
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    Journal of Morphology 46 (1928), S. 563-583 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The urinogenital organs of Myrmecobius fasciatus conform to the marsupial type in both their anatomical characters and histological details. The external genitalia indicate a close relationship with the Dasyuridae.
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    Journal of Morphology 47 (1929), S. 135-199 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Definite information concerning the time of development and location of the different imaginal discs of Drosophila melanogaster was needed in order to interpret especially the gynandromorphs, mosaics, and intersexes that have been extensively reported in cultures of this fly. This information was also desirable for many of the mutant types. It was not known, for example, when an organ was reduced or absent, whether its imaginal disc showed a corresponding reduction, or whether it was full size in the larvae and pupae, and failed to carry through to the later stages.Three mutant types with eyes smaller than those of the wild type, namely, lozenge, bar, and eyeless, were examined. It was found that there is a corresponding difference in size as far back as the imaginal disc could be detected. Similarly for the two mutants, vestigial and no-wing. Conversely for the mutant, bithorax, in which the metathorax is larger than the normal and has assumed many of the characters of the normal mesothorax, the imaginal disc was correspondingly enlarged.It follows that the effects of the mutant genes for these characters can be observed in the very earliest condition of the imaginal disc.
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    Journal of Morphology 47 (1929), S. 201-225 
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    Notes: There are eleven pairs of chromosomes in the somatic cells of the opossum.The sex chromosomes are of the x-x type in the female and the x-y type in the male.The number and type of the chromosomes are constant in the wide variety of tissues and organs studied, except that one dividing giant cell of the spleen showed an 8n number of chromosomes.The arrangement of the chromosomes in equatorial plates is that of an autosomal ring surrounding the centrally located sex chromosomes.
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    Journal of Morphology 48 (1929), S. 45-79 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: It was found that thyroid deficiency in the albino rat (Mus norvegicus albinus) is followed by a trend to increased concentration of epinephrin in the suprarenals. The basis of this lies in the relatively greater retrogression of the cortex as contrasted with the medulla which becomes a relatively greater proportion of the organ as a whole. Confirmatory evidence is found in cell counts per unit area and the part of the disappearance of lipoid from the cortical cells of the suprarenals of thyroidless animals.
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    Journal of Morphology 48 (1929), S. 123-151 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: From a study of over 1000 mothers, the female chromosome number appears to be 2N = 22; N = 11. The male number has not been exactly determined, but is presumably not haploid. Only one maturation division occurs in the parthenogenetic egg, and the authors have seen only one in the sexual egg. During the growth stages of the eggs, the chromatin is totally obscured by a large amount of deeply staining nucleolar material which exhibits several phases. Ultimately, this material is apparently absorbed into the ooplasm. Just before the egg is laid, the ovoid chromosomes, in late prophase or in metaphase, are seen in a germinal vesicle situated always at one side of the egg. The maturation division occurs immediately after egg laying. A degenerate body, hitherto undescribed, is noted in the ripe parthenogenetic egg, situated at the pole opposite the germinal vesicle. It is believed to arise by reorganization of nucleolar substance. The body in the sexual egg desribed by Weismann and Ishikawa ('91) as the Paracopulationzelle is noted and its interpretation by these authors questioned, but, for lack of sufficient evidence, no counter-explanation is offered. The possible relation between experimental sex control and the time of maturation division in the parathenogenetic egg is discussed.
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  • 38
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    Journal of Morphology 48 (1929), S. 253-279 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Technique. This work is based not only on the fixed preparations, but also on fresh cover-slip preparations treated with neutral red or 2 per cent osmic acid for a short time.Golgi elements and fatty yolk. The Golgi elements are hollow vesicular bodies with a distinct osmiophilic rim and a central osmiophobic substance. In the youngest oocyte they form a circumnuclear ring. Gradually the vesicles spread out, grow in size, store up fat in their interior, and give rise to the fatty yolk. On account of their higher refractive index, due to the presence of fat, the Golgi vesicles can be occasionally seen even in the young oocytes without any treatment.Mitochondria. The mitochondrial granules also form a circumnuclear ring and are later distributed uniformly.Albuminous yolk. The albuminous yolk is nucleolar in origin. Early in oogenesis, the nucleous buds off small, homogeneous, and highly chromatic particles in the cytoplasm, which sooner or later disappear. Subsequently, the nucleolus becomes less chromatic and develops vacuolar bodies in its interior, which, becoming vacuolated exactly like the parent nucleolus, migrate into the the cytoplasm. These bodies become more and more chromatic and travel toward the periphery of the egg, where they grow in size. Ultimately they break down into small, homogeneous, and highly chromatic bodies which are the definitive albuminous yolk spheres and which subsequently grow enormously in size.
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  • 39
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    Notes: Maturation of the male germ cells in the rat shows some slight modifications of the typical procedure in sex cells, a distinct and rather prolonged synapsis occurring before synizesis and a confused stage immediately after it. The clumping in synizesis is not extreme. In the mixed strain of rats both twenty-one and thirty-one tetrads appear in the late diakinesis. This procedure in the male resembles the maturation of the oocytes in only two points, the beginning of the process, the deutobroch nuclei, and the end of it when the haploid number of chromosomes take their places on the spindle.
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  • 40
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    Journal of Morphology 48 (1929), S. 493-541 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The cells of the blastoderm which are to form the serosa are two- to four-nucleate; the smaller cells of the embryonic rudiment, uninucleate. The band-like embryonic rudiment encircles the yolk at the equator of the egg. The amnion does not begin to form until after the serosa completely covers embryo and yolk. The epithelium of the midgut arises from cells situated at the tips of stomodaeum and proctodaeum. These cells, though not differentiated from adjacent ectoderm at the time of the invagination, are nevertheless interpreted as part of the preprimordium of the endoderm. In the eighty-four-hour stage a fold of amnion grows over the dorsal side of the embryo, entirely covering it in the course of the next few hours. A portion of the amnion thus forms the dorsal wall of the embryo. At the completion of the amnion the embryo rotates so that its ventral side is directed toward the egg center. The amnion raptures just before the larva begins to feed on the yolk which still remains around it. The serosa is consumed before hatching, which takes place about five and one-half days after deposition.
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  • 41
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    Journal of Morphology 48 (1929), S. 585-609 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The caeca of fourteen bantam fowls have been studied. These fowls ranged in age from six days' incubation to three years after hatching. Between the fifth and sixth days of incubation rectal caeca arise as evaginations from the intestine at the junction of the ileum with the colon. The develoing caeca closely resemble histologically the intestine to which they are attached.The caeca are essentially devoid of content until about the nineteenth day of incubation, but during the remaining days of incubation are gorged with a bluish-gray material similar to that found in the colon. Thus, an early defecatory function is indicated.In general, the proximal third of the caeca remains histologically similar to the intestine, but the distal two-thirds undergoes regression. The latter involves the atrophy of the epithelium and glands, accompanied by the appearance of lymphoid tissue. Much of the lymphoid tissue eventually disappears, to a large extent by atrophy and dissolution of the leukocytes. However, to some extent, lymphocytes develop into granulocytes which escape with other leukocytes into the lumina of the caeca and there disintegrate.Lymph nodules begin to appear in the caeca about one week after the chick hatches. The leukocytes, at least in part, arise in situ from the reticular stroma. Eosinophils arise in certain areas of the tunica propria, and in the earlier stages of their development resemble large lymphocytes, in the cytoplasm of which basophilic, amphophilic, and acidophilic granules are intermingled.
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    Journal of Morphology 45 (1928), S. 599-613 
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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 spermatogenesis was made on four groups of a pedigreed strain of the moth Philosamia cynthia, and the results were compared with spermatogenesis in the wild material.Deviations from the normal number of chromosomes were observed in two groups. In some individuals the haploid number was 12 instead of 13. Giant spermatocytes were also observed with twenty-four chromosomes. In other individuals, two haploid numbers, 13 and 14, occurred in the same testis.The twelve-chromosome condition is due to linkage of two chromosomes during the late prophase of the primary spermatocyte. The double chromosomes thus formed appeared to divide equally in both divisions. The origin of the fourteenth chromosome was not determined.Correlation of the genetic and cytological data indicates the restriction of aberrant chromosome complexes to two of the four groups and the regularity of the twelve-chromosome complex in certain families, suggesting the conclusion that a new strain arose in the pedigreed material with regard to chromosome variability and that the twelve-chromosome condition is a well-defined characteristic, partly established in some families and probably fully established in others.
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  • 43
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    Notes: The spermatogenesis of five guinea-pigs was studied. The spermatogonial chromosome number is approximately sixty-two plus or minus two. The primary spermatocyte number is approximately thirty-one. The spermatogonial number in the early prophase is lower than it is in later stages. This condition is due to late fragmentation of the large chromosomes found in the earlier stage. A possible sex chromosome of the X-Y type may be identified. Its components segregate during the first maturation division.
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  • 44
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    Journal of Morphology 48 (1929), S. 543-561 
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    Notes: The parietal fossa or pit is situated in the middorsal line between the ear capsules. From its floor four (sometimes only two) apertures lead into the ear capsules. The anterior apertures are the foramina of the endolymphatic ducts; the posterior ones are the fenestrae. Through the fossa each endolymphatic duct passes from its formen to its external aperture in the dorsal integument, describing in its course a loop with the convexity directed anteriorly. The part of the duct involving the loop is enlarged into an endolymphatic pouch. Into the angle of this loop a small muscle is inserted which is a continuation of the anterior trunk muscles, or one taking a more lateral origin from the edge of the fossa. The fenestra may or may not be closed by a definite fenestral membrane. The posterior semicircular canal (posterior utriculus) bears a peculiar relation to the fenestra. The endolymphatic pouch, like the sacculus, contains otoconia, and sometimes siliceous sand grains. Various functions have been assigned to the endolymphatic organ. There is no convincing experimental evidence as to its significance.
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  • 45
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    Journal of Morphology 57 (1935), S. 1-29 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two kinds of spermatozoa are formed in the testis of Goniobasis laqueata, typical (eupyrene) and atypical (apyrene); a similar dimorphism is noted in several other related genera. The development of each type of spermatozoon is described in Goniobasis. The apyrene spermatozoa do not appear in the testis until eupyrene spermatogenesis has progressed to the formation of mature eupyrene spermatozoa. After this time apyrene spermatogenesis becomes predominant. It is suggested that this condition is indicative of a modified protandric hermaphroditism, according to a recent theory of spermic dimorphism. The anatomy of the reproductive system of Goniobasis is described briefly, and the behavior and fate of the two types of spermatozoa are noted. Only the eupyrene spermatozoa are inclosed in a spermatophore formed in a special organ of the male, the apyrenes being somehow excluded. Thus the latter do not reach the female in copulation and can have no necessary functional relationship to the ova at the time of fertilization. The delayed formation of the apyrene spermatozoa, and other facts, indicate that they are probably not concerned with the nutrition or transport of the eupyrene spermatozoa.
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  • 46
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    Journal of Morphology 57 (1935), S. 31-59 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The little capsules in which snails of this family deposit eggs are so durable as sometimes to be found adherent to museum specimens; hitherto, however, detailed descriptions of such capsules have been restricted to the capsules long known as made by Neritina fluviatilis in fresh waters of Europe. The present paper adds descriptions, with measurements and sketches, of Neritina reclivata from Florida, Neritina virginea, Neritina punctulata, Theodoxus mneleagris, Nerita peloronta, Nerita alticola, Nerita tesselata and Neritilia succinea from Jamaica, British West Indies.These capsules are found to be remarkable in that the digestive tract aids in their formation; that is, the capsules are made as secretions of the lower oviduct to which mineral particles are added, and these mineral particles are supplied from the intestine and stored up in a special sac opening into the oviduct. Moreover, the mineral particles are of twofold origin; in some Neritinas they come from the ooze taken in with the food and passed through the intestine; in some Neritas they come from the liver as calcospherites, to be passed through the intestine.It is hoped that the data given will aid future descriptions of capsules from other species till a firm foundation is built for utilization of these capsules as aids in taxonomy.
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    Journal of Morphology 57 (1935), S. 105-112 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: There is as yet no proof that the prepollex and postminimus ever occurred as actual digits. Romer's discovery of previous confusion of the preaxial with the postaxial fin border of Sauripterus allows a more accurate interpretation of primitive conditions. The latter involved essential asymmetry. The carpal cartilages of the Sauripterus type offin must have split into transverse rows. When the radius and ulna had become of equal length there was redistribution of the most proximal carpals, thus displacing elements in the other rows. It seems that eventually the original first carpale assumed the position and function of a first metacarpal, while the original fifth metacarpale assumed the position and function of a fifth carpale.
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    Journal of Morphology 57 (1935), S. 113-129 
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The external genitalia of female termites are readily homologized with those of female roaches. Mastotermes and other representative termites from every family are compared and their phylogenetic relationships within the group are found to agree, with the exception of the Hodotermitidae, with those based on studies of other structures.
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  • 49
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    Journal of Morphology 57 (1935), S. 131-145 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A hitherto unknown secondary sex character in male frogs consists of a series of connective tissue bands which extends the entire length of both layers of the Obliquus muscle, at both their dorsal and ventral borders. Extensions of the ventral bands may be carried inward toward the midline at certain of the inscriptiones tendinae. These bands are named the Lineae masculinae. They are clearly visible in specimens from which the skin has been removed, and are visible even through the skin in living specimens of certain species of Kaloula.Ninety-one genera and 553 species of the frogs and toads of the world were examined for the presence or absence of this structure. It is distinct in the common American and European ranids, such as Rana pipiens and Rana esculenta. It is entirely absent in many genera. When present it is found only in adult males, being absent in sexually immature males and females of all ages. Examination revealed no seasonal variations in males of Rana pipiens. This indicates that there is some correlation between the expression of this character and the sexual hormones. No function is assigned to the Linea masculina, although it is suggested that it may be associated in some way with voice production. A discussion of the taxonomic distribution of the character is included.
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    Journal of Morphology 57 (1935), S. 213-251 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The hyobranchial apparatus and throat musculature of the plethodontid salamanders are examined. The interhyoideus is thought to be the homologue of the intermandibularis posterior and the posterior part of the intermandibularis anterior. The quadrato-pectoralis is found only in Desmognathus (Leurognathus?), and Aneides. Its presence in the former is a primitive condition; in the latter, secondary. The gularis had its phylogenetical origin as a slip from the quadrato-pectoralis. The lingual cartilage is found only in Gyrinophilus, Pseudotriton, Eurycea, and Manculus. It is the homologue of the [sehnenplatte] of Salamandra; not the otoglossal. The presence of the suprapeduncularis and the absence of the genioglossus is not peculiar to adult free tongued genera. The anatomical evidence allies Batrachoseps with Hydromantes and Oedipus. The latter two genera are derived from ancient Plethodon stock, not from Gyrinophilus stock. Stereochilus, Typhlotriton, and Typholomolge are the degenerate descendants from ancient Gyrinophilus stock.
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    Journal of Morphology 57 (1935), S. 429-459 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Accounts of binary fission for two species of Chilomastix by Bélar ('21) and Boeck and Tanable ('26) differ. Consequently, investigations were initiated to study the cytology and to determine the nature of binary filssion in Chilomastix mesnili of man, Chilomastix mesnili (?) of anthropoid apes and monkeys, and Chilomastix intestinalis of guinea pigs.The material used for the study included the following: four heavily infected human cases of Chilomastix mesnili, twenty-one infections of Chilomastix mesnili (?) from a survey of thirty-six anthropoid apes and monkeys at the Philadelphia Zoölogical Gardens, and Chilomastix intestinalis from six guinea pigs.The results of the investigations indicate that binary fission of the above three species of Chilomastix are similar in essential details. Encystment is described for the species from man and from anthropoid apes and monkeys. No evidence for mitosis within the cysts was obtained for C. mesnili of man. In C. mesnili (?) from primates other than man, the appearance of cyst nuclei resembling mitotic processes is explained as variations occurring in nuclei. Binucleate cysts are believed to be formed by the encystment of abnormal binucleate individuals which never had undergone plasmotomy after division of the nuclei.
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  • 52
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    Journal of Morphology 57 (1935), S. 275-302 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sexual dimorphism of Chinese cobitids consists of peculiar structures of the pectoral fins and of variations in the lengths of these as well as of the ventral fins. In all groups the paired fins are, as a rule, longer in the male sex, and the female has no lamina circularis, enlargement of pectoral rays or dilation of lateral muscles.In males of Cobitis and Misgurnus, the second rays of the pectorals are enlarged and possess at their base a bony plate (lamina circularis). In other Chinese genera the lamina circularis is absent. Males of the Misgurnus group are easily recognized by the dilation of the lateral muscles in the region of the dorsal fin. Males of Barbatula have several enlarged inner rays in the pectoral fin and numerous nuptial tubercles on the head, arranged in prepercular and preorbital groups. In the European, B. barbatula, however, tubercles on the head are wanting.In males of the Leptobotia and probably Botia groups, the first pectoral ray is enlarged, and the membrane between several of the inner rays is covered with nuptial tubercles.In general, in the Chinese cobitids the differences in sexual dimorphism are correlated with the differences between genera, i.e., each genus possesses a quite different sexual dimorphism; thus the secondary sexual characters can be used for taxonomic purposes.
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  • 53
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    Journal of Morphology 57 (1935), S. 533-545 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The thyroid primordium is a solid median outgrowth from the pharynx which is attached to the truncus arteriosus at its bifuracation. The thyroid is soon detached from the pharynx and migrates to its definitive position ventral to the aorta between the bases of the third visceral pouches. After detachment the primary follicle appears in the lower part of the primordium; during migration and early growth it is divided apparently by stress and pressure to form secondary follicles. Independent follicles are formed also by secretion of colloid between solid masses of thyroid cells. Other secondary follicles are formed by pinching off evaginations from large follicles. Colloid appears soon after the primary follicle is divided. The adult thyroid is a group of follicles scatterd in a venous plexus in the ventral pharyngeal region, around the aorta.
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  • 54
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    Journal of Morphology 57 (1935), S. 617-653 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Three to 5 minutes after implantation of a spermatophore in Placobdella parasitica there is a pronounced granulation of the tissues in the immediate region of the capsule. During the following 20 minutes a path 81 to 120 μ across communicating with the sinuses of the body cavity is established. By a mechanical shrinkage of the distended spermatophore the spermatozoa are injected through this path into the coelomic sinuses. They are dispersed through the body by the haemolymph and possibly by muscular contractions of the recipient. Fifty to 75 hours after their introduction into the body some of them arrive in the ventral sinus. From here they penetrate the walls of the ovisacs and take up a position in the lumina in preparation for fertilization. Two to 30 hours after implantation a plug of cells composed of migrating cellular elements of the recipient's body and of cells introduced along with the spermatozoan bundles forms in the subhypodermal region of the sperm path. Twenty to 45 hours later the wound is entirely repaired. Hypodermal epithelium is replaced by a migration into the affected region of similar reserve cells. The parenchymatous tissue is restored by a differentiation and growth of some of the cellular elements making up the plug.
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  • 55
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    Journal of Morphology 58 (1935), S. 1-39 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Flatfishes lying on one side and that blind and colorless, but having the upper side two-eyed and colored are abnormal fishes which in their own group are perfectly normal. Some normally lie right side up (dextral) others point left (sinistral). Any departure from these normal conditions constitutes such a specimen an abnormal flatfish. The simplest departure is reversal-i.e., a normal dextral fish lies on its right side and points left and vice-versa. Sixteen reversed fishes have been described, but in various species from 3 to 100 per cent reversals have been noted.Reversal might be thought dependent on the structure of the optic chiasma. The Psettodidae (lowest family) have a dimorphic chiasma (right or left nerve dorsal) and are indifferently dextral or sinistral. But the dextral Soleidae and the sinistral Cynoglossidae (highest families) have dimorphic chiasmas with only five recorded reversals. In between, the monomorphic sinistral Bothidae have the right nerve dorsal even in the five indifferent species. And the monomorphic dextral Pleuronectidae include three indifferent species (one having up to 100 per cent reversed) with the left nerve dorsal even in reversed fish. The explanation of reversal must be found in genetics.
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  • 56
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    Journal of Morphology 58 (1935), S. 157-172 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study reveals the existence of four distinct but genetically related types of upper jaw mechanisms:1. The non-protractile, with no mechanism for the protrusion of the pre-maxillae. The maxillaries form part of the upper margin of the mouth, as in Isospondyli, Apodes and Haplomi.2. The crossed ligaments in the snout as in Acanthopteri, Heterosomata and Anacanthini.3. The twisting action type in which the internal hook of the maxilla drives out the pre-maxilla as found in Cyprinodontes and Percesoces.4. The rostral or sigmoid ligament attached to the pre-maxilla as in Cyprinidae and Catostomidae.The three protractile types all possess an enlarged pre-maxilla with a medium dorsal process, suggesting a common origin of all from a single non-protractile form of upper jaw.
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  • 57
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    Journal of Morphology 58 (1935), S. 211-220 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The shell of Cardium corbis is composed of three layers, an outer periostracum of conchyolin and two layers of aragonite. The outer aragonitic layer presents a laminated appearance, but in reality is made up of fibers which extend across several of the curved lamellar lines. Each fiber is enclosed in an organic sheath which can be dissolved in potassium hydroxide. The inner aragonitic layer is composed of vertical prisms which are made up of two sets of fibers inclined to each other at an angle of 55 to 60°. The outer layer of aragonite is secreted by glands on the mantle edge outside the pallial line; the inner layer is secreted by glands on the mantle area within the pallial line. The dentition is formed of the same material as the inner aragonitic layer.The ligament is composed of two layers, the outer being less impregnated with calcium carbonate than the inner. Both layers are continuous with the organic matrix of the shell.
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  • 58
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    Journal of Morphology 58 (1935) 
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  • 59
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    Journal of Morphology 58 (1935), S. 355-383 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: New dissections of the caudal and short posterior thigh muscles of the reptiles Iguana, Varanus, Crocodilus and Testudo, and the mammals Sciurus, Galago and Herpestes were made, and the findings correlated with those described in the literature. The condition in the lizards, Sphenodon and crocodiles is very constant; in each case there is a puboischiofemoralis externus and an ischiotrochantericus passing from the pelvis to the femur, a deep caudal mass passing from the tail to the femur, and a superficial caudal sheet attached to the ilium and ischium. In the Chelonia, with the specialization of the gait, the deep caudal musculature has lost its attachment to the femur, and has migrated onto the vertebral column and the inner surface of the pelvis, while the other muscles occupy their typical position. In the Mammalia the deep caudal musculature has undergone a change similar to that in the Chelonia, forming the pubo-, ilio-, sacro- and ischiococcygeus muscles, while the superficial caudal musculature has disappeared except for a part which forms a sphincter cloacae. The posterior part of the puboischiofemoralis externus has formed the quadratus femoris, and the ischiotrochantericus the obturator internus and the two gemelli. In specialized mammals with reduced tails the caudal musculature has taken over new functions and become respecialized in different ways.
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    Journal of Morphology 58 (1935), S. 419-437 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A histological study has been made of the developing mid-gut or mesenteron of Melanoplus differentialis from diapause until after hatching. The primitive mid-gut consists at first of a single laver os squamous epithelium surrounding the yolk; to this is added later an outer layer. These two layers give rise to the muscular and connective tissue elements of the definitivo mid-gut. Near the of hateching, vitellophanges which have been present in the yolk since earlier stages migrate peripherally to form a lining upon the inner surface of the primitive mid-gut. The vitellophage nuclei divide to form the smaller nuclei of the definitive epithelium of the mid-gut. The vitellophage nuclei divede to form the smaller nuclei of the definitive epithelium of the mid-gut. The development of the definitive mesenteron fron the primitive mid-gut takes place rapidly and occurs near the time of hatching.
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  • 61
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    Journal of Morphology 59 (1936), S. 91-112 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Increases in weight, total body length, and width and length of the head capsule of Japanese beetle larvae were studied. Since the progression factors decreased with succeeding molts and exhibited considerable variation it was concluded that Przibram's principle is inapplicable. Cells were counted in the mid-intestine and brain. Columnar cells of the mid-intestine were measured. The data show: (a) No increase in cell number occurs at the time of molting. (b) The progression in weight and length cannot be correlated with an increase in cell number. In the first instar the progression for increase in weight was 5.73; while for increase in cell number, it was 1.67 for the mid-intestine, and 1.19 for the brain. In the second instar, the corresponding figures were 5.24, 1.98 and 1.69. In the third instar average weight increased 3.18 times, but there was practically no increase in cell number. Thus, molting does not represent a definite increase in number of cells of the insect's body as suggested by Przibram and Megusar, and Bodenheimer's method of calculating cell divisions seems to have no factual basis. Increase in size of the larva is largely due to an increase in cell size. The ratio of increase in total cell volume of the columnar cells of the mid-intestine is approximately equal to the ratio of weight increase.
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    Journal of Morphology 59 (1936), S. 123-161 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An atypical euchromosome, characterized by the large size and deep stainability of its chromomeres during the meiotic prophase, occurs in representatives of seven genera of Acridinae, viz., Chorthippus curtipennis, Euchorthippus pulvinatus, Stenobothrus lineatus, Omocestus ventralis, Stauroderus biguttulus, Gomphocerus rufus, and Aeropedellus clavatus. This element, which is termed the ‘megameric chromosome,’ stains more deeply than the other euchromosomes also during interkinesis and early spermiogenesis. The megameric chromosomes of the individual exhibit striking similarity in the number, size, and arrangement of their chromomeres through successive stages of the meiotic prophase. All the evidence from cytological study indicates that these chromosomes are intergenerically homologous. This is chiefly significant in the support it gives to the theory of chromosome individuality. The heteromorphic megameric tetrad of one individual of S. biguttulus - unequal because of a deficiency - usually undergoes segregation in the second division. The megameric chromosomes display splits previous to synapsis. Pairing begins at their proximal ends and proceeds distally. All the euchromosomes of the spermatid nucleus show splits in preparation for the first cleavage division of the zygote.
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    Journal of Morphology 61 (1937), S. 485-494 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper presents an account of the morphology of the hypophysis and adjacent hypothalamic regions of young adult Amblystoma tigrinum. The description deals primarily with reconstructed models made from blotting paper; transverse and sagittal sections are also considered. A new term, hypophysis, pars subdistalis, is used to describe a discrete portion of the hypophysis embedded in the medial and ventral portion of the pars distalis. The other portions of the hypophysis also are described in detail.
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    Journal of Morphology 59 (1936), S. 163-172 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Serial sections and dissections of the eye and orbit of Holocentrus ascensionis (Osbeck) reveal a relatively well-developed accommodation muscle (m. retractor lentis or campanula Halleri) supplied by a ramus of the short ciliary nerve which traverses the region of the vitreous humor in an invaginated fold of choroid, the processus falciformis. The ramus contains chiefly heavily myelinated nerve fibers with a few finely myelinated or unmyelinated fibers. The type, origin and probable function of these constituents follows: 1.Medullated postganglionic processes of ciliary ganglion cells about which end the preganglionic fibers of the oculomotor nerve.2.Medullated postganglionic fibers from the trigeminal sympathetic ganglion which traverse the ciliary ganglion to join the nerve. These and (4) may supply accompanying blood vessels.3.Medullated sensory fibers to the profundus ganglion.4.Unmedullated or finely medullated fibers from the trigeminal sympathetic ganglion.
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    Notes: This investigation is intended to be the first of a contemplated series to study correlation of diet with morphological change. The material here reported is from grasshoppers on satisfactory diets. The gross anatomy shows a typically acridine arrangement. Fixation with B3 and staining with haematoxylin and eosin shows that peritoneum, muscle and chitin in different areas vary only in arrangement and relative development. The epithelial cells of the various regions differ in structure as well. Modifications of the cytoplasmic elements of these cells are correlated with cellular activity. The epithelial cells of the mid-gut and its six bi-lobed gastric caeca, and of the six rectal glands have a striated border of separate filaments which are cilia-like in appearance but devoid of motion. The caeca are most active in gastric secretion, which is merocrine or holocrine according to conditions. Essentially different granules and vacuoles are secreted, and extruded by rupture of the cells; which are replaced from nidi.
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    Journal of Morphology 58 (1935), S. 285-353 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The larval epithelium cells of Mycale syrinx (O. Schm.) unite syncytially with one another. The stratum so formed is continuous with the syncytial interior of the larva and into this interior the epithelial nuclei are drawn. Many of them degenerate and are digested by the syncytium or, eventually, by nucleolate cells. The syncytial cytoplasm breaks up into cell bodies, some surrounding epithelial nuclei and thus forming choanocytes, others surrounding nucleolate and non-nucleolate mesenchyme nuclei. The larval epithelial cells do not then become the choanocytes. Only their nuclei are specifically determined. The bodies of the choanocytes are picked out of the general syncytium in accordance with the location which the nuclei may occupy at the time. Non-nucleolate cells of the interior break through to the surface and form epidermis. Or non-nucleolate nuclei, usually not in special cell bodies but in the general syncytium, are drawn to the surface, the surface layer there condensing to form epidermis.There is a provisional formation of limiting membranes by the reticular syncytium around spaces of the interior and at the surface. The definitive cellular membranes, epidermis and canal epithelia, are only completed later. Some mesenchyme cells may be digested by the general syncytium. Such cells lie in vacuoles, as in a digesting protozoan.
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    Journal of Morphology 58 (1935), S. 385-417 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The anatomy of the lymphatic system of the snake is described, together with some preliminary observations of the blood vascular system. Lymphatic vessels are numerous and thin-walled, chiefly periangious, but some are in close relation to the vertebral, column. The aortic lymphatic enlarges to form a sac in the abdominal region which encloses several of the viscera and in many cases communicates with their connective tissue sheaths. Lymph vessels in the skin and body musculature form a regularly arranged segmental network. The system communicates with the blood vascular system in two places: by means of a pair of posterior lymph hearts in the region of the cloaca, and at the jugular lymph sac just craniad to the heart. The arrangement and distribution of lymphatic structures is of interest in relation to phylogenetic development and because of the specialization of structure due to the elongate form of the snake.
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    Journal of Morphology 58 (1935), S. 463-535 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A histological study has been made of the developing mid-gut or mesenteron of Melanoplus differentialis from diapause until after hatching. The primitive mid-gut consists at first of a single layer of squamous epithelium surrounding the yolk; to this is added later an outer layer. These two layers give rise to the muscular and connective tissue elements of the definitive mid-gut. Near the time of hatching, vitellophages which have been present in the yolk since earlier stages migrate peripherally to form a lining upon the inner surface of the primitive mid-gut. The vitellophage nuclei divide to form the smaller nuclei of the definitive epithelium of the mid-gut. The development of the definitive mesenteron from the primitive mid-gut takes place rapidly and occurs near the time of hatching.
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    Notes: The ‘germinal crescent’ of the primitive streak stage chick embryo is located in the zone of junction anterior and lateral to the proamnion. The primordial germ cells supposedly arise from this area.The following experiments were carried out. 1. Complete removal of the germinal crescent. 2. Partial removal of the germinal crescent. 3. Removal of areas of corresponding size of the blastodisc other than the germinal crescent.The results are as follows: In experiment 1, a careful search of the entire specimen failed to reveal any primordial germ cells. Such embryos invariably died during or before the fifth day of incubation.In experiments 2 and 3, the presence of the primordial germ cells was quite obvious. Such embryos did not invariably die. Some from each group was brought through to hatching, with the exception of that group in which the piece was taken from the lateral region of the blastodisc. In this case the injury to the circulation was too great to overcome.As was to be expected, in those specimens in which the circulatory system was injured rather severely death always ensued and occurred before the third day of incubation regardless of the type of experiment.Both cauterization and removal with scissors were tried. Mechanical removal gave superior results and was used exclusively in the latter part of the experiment.
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    Journal of Morphology 58 (1935), S. 615-637 
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Chordotonal organs are present in the prothoracic, mesothoracic and metathoracic femora of Melanoplus differentialis. These have been described and their development traced from ectodermal invaginations located at the proximal and distal ends of the prothoracic and mesothoracic and at the distal end of the metathoracic femora of the embryo.
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    Journal of Morphology 60 (1936), S. 159-187 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The development of the nervous system is traced by stages and, in general, is found similar to that already described for other insects. Terms such as ganglionic gangliomeres, medullary masses, optic nerve, etc., are shown to have no significance. The intraganglionic thickening of Viallanes is shown to be a misnomer. A chronological table of the developmental processes is appended.
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    Journal of Morphology 60 (1936), S. 191-209 
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    Topics: Biology , Medicine
    Notes: Differing from hitherto known spermatophores, these are found to have the form of a loop with a thick body and the slender ends twisted together.Also one end bears a spiral row of triradiate spicules, unique in being chitinoid secretions. Each is formed within a vacuole of a cell of a small gland found in the males. The ends of the spermatophores hold sperms, but the main mass consists of granules of problematical value. Spermatophores after discharge are stored up within the female, where remnants of them remain indefinitely.For the first time stages in the formation of spermatophores were found within the males. The head organ in the male is found to be more complex than hitherto known in this genus. A special head organ in the female is described for the first time in this family. An hypothesis is advanced as to the possible use of these male and female head organs in transfer of spermatophores. The suggestion is made that in this family the spermatophores and their organs of transfer and of storage may serve as generic characters.
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    Journal of Morphology 60 (1936), S. 243-259 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The post-embryonic growth of the notochord, sensory retinal cells, cartilage and gut epithelium in frog tadpoles, trout and lamprey is described. Increase in the number of notochord and sensory retinal cells results only from the mitotic division of cells which have not yet undergone the structural modifications characteristic for these cells. The specialized and functional cell does not divide. In the frog tadpole the cartilage cells increase by mitotic division of the fully-formed and functional cell: in addition there are centers of proliferation consisting of small, rapidly-dividing cells. The trout is similar except that there are no centers of proliferation, in addition amitotic division occurs. The gut epithelium grows by mitotic division of the functional constituent cells. During division the cell assumes a spherical shape and its functional activities are suspended.
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    Journal of Morphology 60 (1937), S. 317-324 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The last muscle in the transverse superficial throat series in all genera of salamanders is here called ‘gularis.’ This eliminates a long list of synonyms. A description of its metamorphic changes in Dicamptodon (Ambystomidae) and comparison of the larval and adult conditions in this genus with those in other known genera clears up the homologies of the muscle throughout the series. The study is based on dissections and a survey of the literature covering all important groups except the Hynobiidae.
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    Journal of Morphology 59 (1936), S. 351-399 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: During the quiescent fourth larval instar the larva of Drosophila becomes loosened from the puparium and takes on the form of a pupa. A large gas bubble is formed within the body during this prepupal period. At the end of this stadium, which lasts 11 1/2 hours at 25°C., it pupates, shedding the prepupal cuticle. The gas bubble is used as a mechanism to separate the cuticie from its hypodermis. Practically all of the tissues undergo histolysis and are replaced by imaginal structures derived from specialized cells. Some of the muscles persist longer than the general mass and perform special functions in the pupa. The sequence of histolytic and histogenetic changes is accurately timed at a constant temperature.
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  • 76
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    Notes: Since differential maturation has been used in explaining sex determination in Hymenoptera, the pertinent stages were studied cytologically in Habrobracon by using whole mounts of timed eggs stained by the Feulgen reaction.The egg is laid with the maturation figure in an arrested first anaphase close to the ventral egg surface, and with the spindle horizontal to the latter. Eggs from different stocks show differences in position of maturation figure. A single sperm enters during oviposition, the maturation spindle revolves to a vertical position and normal maturation and change of the sperm ensues. Nuclei of unfertilized eggs behave similarly. Ten chromosomes enter each of the three polar and the one matured egg nuclei, the latter being always the innermost of the four. Unfertilized eggs have ten chromosomes at first and eleventh cleavages; fertilized eggs have around the expected twenty. Chromosomes in maturation divisions are too small and round to show individual differences. There is no good evidence of chromosome elimination.
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  • 77
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    Journal of Morphology 59 (1936), S. 549-587 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The phytosaur of the Triassic exhibits many interesting adaptive modifications of the diapsid skull. The modifications of the muscle attachment areas for the jaw muscles have been examined in comparison with the musculature of the recent forms Sphenodon and Alligator. It has been determined that the development of the fleshy anterior pterygoid and of the intramandibular muscles is an adaptation concomitant with the elongation of the snout. The modification of the temporal region in the phytosaur with the posterior extension of the squamosal is also seen to be an adaptation to gain speed in closing the great mouth. The forward position of the head-neck joint would appear to gain advantage in the support of the heavy head. Such similarities as are seen between the phytosaur and the crocodilian may be accounted for as parallel adaptation.
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  • 78
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    Journal of Morphology 60 (1936) 
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  • 79
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    Journal of Morphology 60 (1937) 
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  • 80
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    Journal of Morphology 60 (1936), S. 287-315 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The musculature of forearm and manus basically is divisible into dorsal matrix and ventral matrix of elbow, and dorsal matrix and ventral matrix of the podium. The former contributes to the present musculature of brachium and antibrachium, and the latter to the musculature of antibrachium and podium. The forearm muscles of the former category are divisible into humero-radial (carpi radialis), humero-podial (digitorum communis et sublimis), and humero-ulnar (carpi ulnaris) components. The deep muscles of the forearm (mm. abductor pollicis longus, extensor pollicis longus, extensor indicis proprius; flexores digitorum profundus et pollicis longus) have been derived from podial matrices that have migrated proximally along the ulna. The short flexors of the hand have been derived from a superficial and a deep basic series: From the former have come mm. palmaris brevis, abductor pollicis brevis, superficial head of the flexor pollicis brevis, abductor et flexor digiti 5, and lumbricales. From the deep series have been derived mm. contrahentes (including adductor pollicis), interossei, opponens pollicis, deep head of flexor pollicis brevis, and opponens digiti 5.
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  • 81
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    Journal of Morphology 61 (1937), S. 127-148 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: The Gelgi bodies in Meretrix casta being visible in fresh eggs, an attempt was made to elucidate the nature of the contents of neutral red vacuoles. These are neo-formations which arise on treatment with neutral red Ringer. As recent researches have shown that neutral red forms compounds with enzymes, it is suggested that the new vacuoles in Meretrix are visible products of the attempt of the Golgi apparatus to eliminate neutral red which is a foreign substance to the egg. The function of Golgi bodies in the control of cell metabolism by production of intra-cellular enzymes is discussed.
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  • 82
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    Journal of Morphology 61 (1937), S. 175-221 
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    Notes: The reproductive organs of Bruchus quadrimaculatus Fabr., and B. (Callosobruchus) chinensis L., including histology are described in detail. The role of the different parts of the male and female copulatory apparatus is discussed and the physical composition and function of the secretions of the accessory glands are indicated. The specific differences in the structure of the genitalia of the two species are shown.
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  • 83
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    Journal of Morphology 60 (1936), S. i 
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  • 84
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    Notes: Two sizes of cells are found in the mid-gut epithelium of late embryos. The larger cells contain nuclei having twice the number of prochromosomes and nearly twice the volume as compared with the nuclei of the smaller cells. During each larval instar, the nuclei of the functional mid-gut epithelium nearly double their volume and there is a corresponding increase in the amount of chromatin. It is suggested that chromosome division without nuclear division occurs in these epithelial cells during the pre-ecdysial periods of each instar. The mid-intestinal epithelial cells and their nuclei undergo characteristic changes during the feeding and pre-ecdysial periods of each instar. Prochromosomes as well as cytoplasmic globules, which represent a cytoplasmic diminution process, are visible in the latter period. The regeneration cells which give rise to the pupal and mid-gut epithelia have origin from the small embryonic mid-gut cells and from nuclei and cytoplasm derived from the larval epithelium by means of an apparent ‘pseudoreduction’ of the large larval nuclei during the late third and fourth instars.
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  • 85
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    Journal of Morphology 61 (1937), S. 165-173 
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Observations are reported which fully establish the aglomerular nature of the kidney in the following teleostean species: Hippocampus trimaculatus, Hippocampus kuda, Hippocampus hudsonius, Microphis boaja, Batrachus grunniens and Pterophryne histrio. It is possible that we are dealing with an additional aglomerular species (Microphis sp.), but this cannot be determined from the available material. All species were taken in sea water except Microphis boaja and Microphis sp., which were taken in fresh water.
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  • 86
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    Journal of Morphology 61 (1937), S. 285-307 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytoplasm of Opalinid infusorians contains two principal components; the mitochondria and the vegetative granules of the endoplasm. A third component in the form of Golgi bodies has been previously described. Under the influence of radium radiations the mitochondria are re-orientated so that they assume a transverse polarity to the longitudinal axis of the organism. Later the mitochondria are segregated by the radiations so that they lie apart from the vegetative granules with which they are closely associated in the normal organism.
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  • 87
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    Notes: The development of the gonads of the marsh hawk, Circus hudsonius, Cooper's hawk, Accipiter cooperi, and the red-tailed hawk, Buteo borealis borealis has been investigated. The occurrence and relatively long persistence of the cortex on both testes of the marsh hawk is evidence of bilateral amphisexuality in this form. The embryonic condition of the ovaries is related to the degree of asymmetry in the adult organs. Nearly symmetrical, paired ovaries were found in three species and varying amounts of reduction of the right ovary in all others.The disappearance of the right oviduct in the ontogeny of the female red-tailed hawk and the occurrence of accessory gonad tissue in male embryos of the same species are described and figured. The extent of reduction of the right ovary of eleven species is described, figured and classified. The following species are listed in the above order of classification: Circus hudsonius, Accipiter cooperi, Accipiter velox velox, Accipiter atricapillus atricapillus, Falco sparverius sparverius, Aquila chrysaëtos canadensis, Buteo borealis borealis, Buteo lineatus lineatus, Buteo lagopus sancti-johannis, Cathartes aura septentrionalis, Buteo platypterus platypterus.It is concluded that two ways by which organs may disappear are realized in the right ovary and oviduct of the hawks. (1) by failure of an embryonic inductor in the case of the ovary, and (2) in the right oviduct by secondary atrophy of an originally well-developed embryonic structure.
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  • 88
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    Journal of Morphology 61 (1937), S. 433-451 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The nasal capsule of the chameleon differs greatly from that of other lizards in several respects. Cartilage is extremely persistent, particularly in the roof. The anterior chamber is produced backward to form an accessory posterior chamber. This posterior extension lies lateral to the olfactory chamber, from which it is incompletely divided by a longitudinal fold which may represent the normal concha.The organ of Jacobson is extremely reduced and occupies an abnormal position with relation to other structures. The olfactory nerves and their branches are much reduced, and the olfactory epithelium is poorly developed. The chameleon is at best a microsmatic animal.
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  • 89
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    Journal of Morphology 60 (1937), S. 489-519 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Plethodon cinereus is favorable for a study of the history of the germ line. The germ cells are large, while the gonads are small and show an almost diagrammatic structure. Germ cell degeneration is not extensive during ontogeny. As long as all the germ cells contain yolk during development, these cells are derived solely from germ cells. In Plethodon, yolk lasts in all germ celis through sex differentiation. A comparison of the number of mitoses necessary for the primordial germ cells to produce the numbers of germ cells in gonads where every germ cell contains yolk, with the mitoses necessary for the primordial cells to produce the adult complements of germ cells, shows that at least 72% of the increase of germ cells can be followed by yolk. A cytological study from the embryo through the adult sexual cycle gave no evidence that somiatic cells ever transform into germ cells. Mitoses are abundant in the testes of salamanders starved 4 months. This fact together with a statistical study on the adult male sexual cycle indicates that the germ cells present in the testis do not need to be augmented by transformed somatic cells. It is concluded that in Plethodon germ cells alone give rise to germ cells, and that the germ line is continuous.
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    Journal of Morphology 62 (1938), S. 3-15 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Comparisons have been made of the weights of the suprarenals of 525 mature female dogs in dioestrus, oestrus, pregnancy and lactation. Tables and graphs show that there was a slight increase in the size of the suprarenals during oestrus. There was hypertrophy of both the cortex and the medulla in the oestrous dogs. Only slight increase was shown in the weights of the glands of pregnant animals when the net body weight was considered and no increase when the total body weight was used in the study. There was no hypertrophy of the glands of lactating animals.There was only a slight variation in the seasonal occurrence of oestrus. From 34 to 37% of the total numbers of mature females examined in the seasons were found to be in oestrus. From 13 to 16% of the total numbers were found to be pregnant.
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  • 91
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    Notes: Nucleoli in the germ cells of certain Orthoptera, Hemiptera and the crayfish have been studied. In Ceuthophilus (camel cricket) these bodies are found to be definitely connected with chromatin threads and are believed to be products of chromatin.The large structure in the ova of Nemobius (cricket) is interpreted as a nucleolus because of its very irregular behavior and apparent complete disappearance.It is found that some of the nucleoli of Gelastocoris (toad bug) arise within the chromatin threads.Observations on Cambarus (crayfish) fail to show nucleolar extrusion, a phenomenon which has formerly been reported for this form.The unique behavior and fate of the nucleolar material in Pselliopus (true bug) is described. In this species the nucleolar material is added to and becomes part of the general oxychromatin network of the nucleus.This study fully supports the opinion that nucleoli have a chromatin origin.
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  • 92
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    Notes: A new limb skeleton will form in regenerating limbs of the larval Amblystoma in which the humerus had been completely removed. The cartilage of the new limb skeleton develops out of a blastema in which there are no cells of cartilage origin. This regeneration blastema is a composite structure made up of cells derived from a dedifferentiation of the injured tissues of the limb. The tissues which have been observed as contributing to the regeneration blastema are: muscles, especially the muscles of the shoulder; connective tissue of the sheath of the brachial nerve plexus; muscle connective tissue; and, to a certain extent, subcutaneous connective tissue. The new cartilage of the limb skeleton develops out of this composite blastema by means of a differentiation of cells in the central axis of the blastema.The amount of cartilage regenerated appears to depend on the mass of the blastema. When the blastema does not extend fully into the glenoid cavity of the scapula, the head of the developing humerus is deficient in size and structure. However, a complete limb skeleton is regenerated when the blastema does extend fully into the glenoid cavity.Since the new cartilage of the regenerated limb has no genetic continuity with the old limb skeleton, it would appear that the limb field exerts some kind of histogenetic determining action.
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  • 93
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    Journal of Morphology 62 (1938), S. 263-297 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Artemia salina, a very widely distributed species in North America, Europe and Asia, breeds freely and rapidly under laboratory conditions, living in all salinities from fresh water to almost saturated brine. Its soft exoskeleton permits of easy sectioning.The morphology and embryology of the segmentally arranged excretory glands - the antennal, mandibular and maxillary glands, are described. The antennal gland, consisting of extracellular end sac and intracellular excretory duct, is located in the second antenna and opens to the exterior on the lateroposterior face of the protopodite. It attains its maximum development by the sixth instar, degenerating by the tenth. The vestigial mandibular gland consists only of an end sac surrounding a schizocoele, and a rudimentary duct. The large maxillary gland in the adult consists of an end sac, an excretory duct of three circular coils, and a terminal duct opening to the exterior. The maxillary gland develops from a mass of mesenchyme cells in the maxillary segment of the nauplius, becoming fully differentiated by the sixth instar.The vestigial second maxilla has two bristles. It serves only as a terminus for the maxillary gland. A pair of small ganglia are accepted as internal evidence for the presence of a maxillular segment.The presence of three pair of schizocoeles in three consecutive segments is interpreted as evidence of homology with the Annelid coelome, with the possibility of further homologizing the excretory ducts with the segmental nephridia.
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    Journal of Morphology 62 (1938), S. 503-521 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In early embryonic stages of Passalus there are, in addition to the brain and suboesophageal ganglion, three thoracic and ten abdominal ganglia; one ganglion to each body segment. Before hatching the tenth, ninth and eighth abdominal ganglia coalesce. During the three larval instars the terminal ganglion remains in the sixth abdominal segment and only minor changes occur. By the end of the third day of pupal life the adult form of the nervous system is practically assumed. All abdominal ganglia are fused into a single, solid, elongated ganglionic mass. Connectives have disappeared between meso- and meta-thoracic and between metathoracic and abdominal ganglia; and with exception of the brain, sub-oesophageal and prothoracic ganglia, the entire ventral chain has come to lie in the mesothorax. The peripheral nerves still arise from the ganglia and ganglionic mass in their same relative positions and still supply the same segments in which they were originally located.
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    Journal of Morphology 62 (1938), S. 599-607 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Analysis of measurements of the trunk region of the vertebral column and of the various segments of the wing and leg skeleton in sixty-four specimens (thirty-four males, thirty females) of Fulica americana shows that: The males average about 7% larger (longer) than females in all parts of the skeleton; the difference is uniform throughout the body. The coefficient of variability ranges from about 3.00 (humerus, et al.) to about 5.00 (hind toe). The correlation between lengths of parts is very high between different segments of the wing skeleton, or of the leg; it is somewhat less between homologous segments of the wing and leg; and it is still less between limbs and trunk. This decreasing order of correlation indicates an increasing order of independence of variability. The wing proportions in Fulica are those characteristic of the type of flight called flatterflug. The proportions of the leg are those of a bird moderately adapted for cursorial locomotion; the very long toes characterize a swimming bird.
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  • 96
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    Journal of Morphology 150 (1976) 
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    Journal of Morphology 150 (1976), S. 19-58 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A thin, compressible, lateral suture and ventral plate overlap permit limited movement of the thick and rigid dorsal and ventral plates of Fuscouropoda agitans. Seven pairs of large dermal glands debouch onto the surface. Trochanteral rotation permits defensive leg adpresion and an insectan type of ambulation. The complex hypopharynx-pedipalpal-coxae has a buccal and cheliceral cavity separated by an atriculated epipharynx. The pharynx is Y-shaped in cross section. Extensive paired salivary glands lie above the very long and dexterous 3-segmented chelicerae, and a large pair of coxal glands debouch on coxae 1. From four blunt-ended tracheae, bundles of unbranching tracheoles extend in specific tracts to all organs. The ventriculus is small with three pairs of large caeca; a tightly packed single layer of digestive cells individually enlarged to absorb-phagocytize and digest the food. A typical mesostigmatid excretory tube is present. A typical acarine synganglion is present; mixed nerves have a basal swelling. A postulated neurosecretory organ arises from the pedipalpal nerve. The oocytes enlarge within funicular stalks from the walls of the small median ovary. A large spermatophore is stored in the seminal vesicle; fertilization occurs during oviposition. A tension hinge partially opens both male and female genital plates; closure effected by muscles acting on very long genital plate apodemes. Within sequentially produced spermatogonial cysts of the testes, meiosis is completely synchronous. A large, multilobed male accessory gland produces a large volume of seminal fluid; a mixture of at least four secretions. The origins and msertions of the body wall, genital organ, digestive tract, mouthpart and leg muscles are listed and illustrated. A comparison of anactinotrichid and actinotrichid mites indicates fundamental and consistent morphological differences in aspects of the cuticle, leg articulations, digestive system, excretory system, reproductive system and coxal glands.
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  • 98
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    Journal of Morphology 150 (1976), S. 279-297 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An investigation of the structure of the iridescent scales of the green hairstreak, Callophrys rubi, reveals an internal lattice which is probably cubic close-packed in form. We present a model which explains the formation of the lattice in terms of packing of spheres and surface tension forces and generalize these results to internal structures in other Lepidopteran scales.
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  • 99
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    Notes: There are 36 to 42 taste bristles on each half of the labellum of Drosophila melanogaster; most of them are two-pronged with a pouch between them. Some end bluntly with a pore at the tip.Each taste-bristle has two lumina: one is circular, the other crescent-like in cross section. In most bristles four dendrites of chemoreceptor neurons run along the circular lumen. In five to seven taste-bristles only two chemoreceptor neurons are found. A mechanoreceptor neuron sends a dendrite to the base of each taste-bristle.The dendrites are surrounded by four concentrically-arranged sheath cells. The inner cell secretes the cuticular sheath; cells II and III are presumably two trichogens, one secreting the bristle material around the circular lumen, the other around the crescent-like lumen. Cell IV, especially rich in bundles of microtubules, secretes the cuticle of the socket, and corresponds to the tormogen. The neurons have the typical structure found in insect sensilla. In many sensilla one neuron is less electron-dense than the others and may be the water-sensor.On the medial side of the labellum between the pseudotracheae are rows of taste pegs covered by folds. In each peg one chemoreceptor and one mechanoreceptor are found.The number of axons in each labial nerve agrees with the total number of dendrites in all taste organs of each lobe.
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  • 100
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    Journal of Morphology 150 (1976), S. 359-368 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Stereological analysis of the ultrastructural composition of the pulmonary alveolo-capillary region of mice living at sea level compared with that of the same species (Phyllotis darwini) genetically adapted to life at 4,660 m reveals a trend at high altitude towards a greater volume percentage of tissue components. On a weight-specific basis, non-circulating tissue occupies a significantly greater volume in high-altitude mice, but air space and capillary contents are not correspondingly greater. Since the arithmetic mean thickness of the tissue layers and of the air-blood barrier are the same in the two altitudinal groups, the average alveolus must have a smaller volume in the high-altitude mice.Epithelial, endothelial, and erythrocyte surface areas per gram body weight are significantly greater in the high-altitude mice.Nuclear counts indicate that the larger lungs of mice adapted to high altitude are due to larger Pneumocyte I and II and endothelial cells rather than to an increase in the number of these cells. Hematocrits measured within the pulmonary capillaries in the two altitudinal groups were equal.An heretofore unrecognized feature of possible adaptive value is the surface/volume ratio of erythrocytes, which is similar for erythrocytes in alveolar space of mice at low and high altitudes but within lung capillaries is 14.7% greater at high altitude.
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