bluuebunny/crossref_metadata_2025 huggingface dataset:
The formation of the sex glands and germ cells of mammals. II. The history of the male germ cells in the albino rat
Authors: Hargitt Geo. T.
Published: February 2005

The testis is differentiated from the indifferent gonad in embryos of fourteen days. The indifferent gonad and the sex cords contain large and small cells, both of which are derived from the coelomic epithelium. The large cells have generally been called primordial germ cells, they increase by mitosis and reach their maximum in embryos of seventeen days. But all the large cells degenerate and have completely disappeared by nine days after birth. The large cells, therefore, do not contribute to the formation of cells in the tubules of the adult testis. After the disappearance of the large cells, the solid seminiferous tubules are composed of indifferent epithelial cells of a uniform type, which are descendants of the small cells of the genital ridge, and which later form both the germ cells and the Sertoli cells of the seminiferous tubules of the adult testis.

Definitive spermatogonia begin to form fifteen days after birth, when the solid cords are becoming hollow tubules; spermatocytes occur at twenty‐three days, when the testes are entering the inguinal canals; spermatids are first observed about thirty‐three days, when the testes enter the scrotum, and perfect spermatozoa at forty‐eight days. Sertoli cells cannot be clearly distinguished until almost puberty; these cells may be only indifferent epithelial cells. During the development of the seminiferous tubules, a good many cells of all stages of spermatogenesis degenerate.
The development of the premandibular head cavities and the relations of the anterior end of the notochord in the chick and robin
Authors: Adelmann Howard B.
Published: February 2005

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.
The structure and division of paramecium trichium stokes
Authors: Wenrich D. H.
Published: February 2005

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.
Freezing and survival of insects at low temperatures
Authors: Payne Nellie M.
Published: February 2005

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.
The development of the eye muscles of the chick
Authors: Adelmann Howard B.
Published: February 2005

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.
The effects of certain physical and chemical factors on locomotion and others life‐processes in Amoeba proteus
Authors: Hopkins D. L.
Published: February 2005

Amoeba proteus was raised in a modified and diluted Ringer solution. When the pH of this culture medium became less than 6.0, the normal activities of the amoebae were interfered with; and when a still lower pH was attained, the amoebae died off. The same was true when the pH became greater than 8.0. At neutrality the activities were subnormal, very dark, and rounded. The rate of locomotion of amoebae raised in solutions with a pH less than 7.0 showed a maximum rate of locomotion at pH 6.6, which decreased as the pH changed in either direction, dropping to a very low rate at pH 7.0 and above and also below 6.0. For amoebae raised at a pH above 7.0 the rate was maximum at pH 7.6 and decreased as the pH changed in either direction; it was low at pH 7.0 and below and also above 8.0.

On increasing the external osmotic pressure of the medium it was found that the effects caused varied somewhat with the hydrogen‐ion concentration. Small increases in osmotic pressure decreased the rate from the normal at pH 6.0 and 8.0, increased it at pH 6.6 and 7.6, and did not affect it at pH 7.0. Osmotic pressures above that produced by M/20 lactose caused locomotion to cease in a short time at all pH values.
Spiral movement in man
Authors: Schaeffer A. A.
Published: February 2005

Blindfolded persons walk, run, swim, row, and drive automobiles in clock‐spring spiral paths of greater or less regularity when attempting a straightaway. The spirals turn either right or left in one and the same individual, and may do so even in one experiment. But either right or left turns predominate in the great majority of individuals, often to a high degree. The paths show marked individuality, and there is some ground for thinking there exists a correlation between temperamental differences and general character of path.

The mechanism which produces the spiral path is not located in the locomotor organs, but in the central nervous system and is probably identical essentially with the spiral mechanism in other motile organisms, all of which move in spiral paths when there are no guiding senses to direct the path. The clock‐spring spiral in man is interpreted as the expression in two dimensions of space of a helical spiral mechanism which seems to exist in all motile organisms moving in three dimensions of space and in amebas which move in two dimensions. In a large number of lower organisms the number of body lengths per spiral turn is almost constant, being about 4.5. The smallest regular swimming spirals in man are very close to this value, but the smallest regular walking spirals are somewhat larger. The fundamental spiral mechanism seems to be of molecular dimensions, and there seems to exist a demonstrable locomotor bilateral asymmetry in very nearly, if not quite, all organisms.
A comparative study of the spermatogenesis of five species of earwigs
Authors: Morgan William Pitt
Published: February 2005

The following species of earwigs are used in this study: Labidura bidens, Labia minor, Anisolabis annulipes, Anisolabis maritima, and Forficula auricularia.

In all species the chromosomes are divisible into, a) autosomes and, b) XY‐complex.

The chromosome distribution in regular in Labidura bidens and Labia minor. The male diploid number is 12 and 14, respectively. Each has an XY‐complex in which the X is a single chromosome.

In both Anisolabis annulipes and Anisolabis maritima the male diploid number is 25, or 22 autosomes and an XXY‐complex. The two X components remain fused during the first spermatocyte division.

The diploid number in the male of Forficula auricularia is 25 and 24. The chromosome number is constant in the individual. The irregularity is interpreted as due to the fusion of the two X components in the individuals with 24 counts and to these X components remaining separate in the earwigs with the 25 counts.

An explanation is given for some of the variable results obtained in former studies of the chromosomes of Forficula auricularia.

The discussion considers the possible origin of the variations in chromosome numbers in the earwigs.
Observations on the gross and microscopic anatomy of the sloths (Bradypus griseus griseus Gray and Choloepus hoffmanni Peters)
Authors: Wislocki George B.
Published: February 2005

In this study observations are reported upon the morphological differences between the three‐toed and two‐toed forms of sloths, as well as a comparison made of some aspects between the sloths and the other groups of the Xenarthra. Much attention has been paid to the gross, as well as the histological examination of the viscera, musculature, and the vascular and lymphatic systems.

The importance of the correlation of the morphological findings with physiological studies has been emphasized. For example, the probable correlation of the vascular plexuses of the extremities with the postures and muscular activity of the different members of the Xenarthra is discussed. Much new information has been gained concerning the placentation and development of the sloths, as well as concerning the structure of the male and female reproductive tracts.
The septomaxillary of the Amphibia Anura and of the Reptilia. II
Authors: Lapage Enid Oldham
Published: February 2005

The septomaxillary is described in certain anurans and in some of the reptiles in which it occurs. In urodeles and some anurans this bone arises by ossification of the nasal cartilages. Lack of embryological material has prevented the verification of this in the young stages of the reptiles. Adult reptiles have been examined, and in these the bone appears to be and has often been described as a ‘membrane bone.’ It is suggested, however, that the septomaxillary is originally a ‘cartilage bone,’ and that in the reptiles additional membrane bone layers form its main part and obscure its cartilaginous origin. The infolding of the bone in the anurans and reptiles until it lies in close contact with the nasal septum, and thereby loses contact with the external nasal structures, appears to be correlated with the loss of the external nasal muscles. This loss in its turn results from the adoption of terrestrial life and consequent changes in the respiratory mechanism.
The significance of the ultimobranchial body (postbranchial body, suprapericardial body): A comparative study of its occurrence in urodeles
Authors: Wilder Magel C.
Published: February 2005

The significance of the ultimobranchial body has been the object of a comparative study of the structure in twenty‐four species of urodeles. In nineteen of these it has not hitherto been described.

Caudal to the last branchial arch, it develops as a thickening and later as an outpushing from the ventral wall of the pharynx. Due to the growth mechanics of the region, it comes to lie obliquely to the pharynx, ventral to it, and dorsal or dorsolateral to the pericardial cavity in its anterior region. It persists throughout life as an epithelioid or epithelial structure, usually of irregular shape, frequently containing vesicles; in some cases it exhibits a considerable amount of secretory activity of variable quality. Except in Amphiuma and Necturus, where it is regularly paired, and in occasional instances in individuals of other species, where it occurs on both sides, it is usually present on the left side only. Its occurrence is constant in all of the species of urodeles for which it has been examined.

It is variable in size, form, and position. This, together with the quite inconstant indication of secretory activity, marks it as a structure of little or no physiological significance. ‘Colloid’ is, however, present in some instances, and hence a comparison with the thyroid was considered.
Growth and maturation in the parthenogenetic and sexual eggs of Moina macrocopa
Authors: Allen Ezra , Banta A. M.
Published: February 2005

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.
A connecting link between the Annelida and the Echiuroidea (Gephyrea armata)
Authors: Heath Harold
Published: February 2005

During the course of a hydrobiological survey of Monterey Bay, California, a series of pelagic organisms was taken at a depth of approximately 350 M., which appears to be a link connecting the Echiuroidea (Gephyrea armata) on the one hand and the polychaetes on the other. The range in body length is from 5 mm. to 27 mm.; and in an extended condition the anterior end of the body, with its palps and cirri, bears a close resemblance to a nereid. The supra‐oesophageal ganglia and the ventral nerve cord, with eleven pairs of ganglia, are also strikingly annelidan in character. On the other hand, the spacious coelom, communicating with the exterior by a pair of anterior nephridia, allies it with the gephyreans. The same is likewise true of the gonad, which arises from the coelomic epithelium surrounding the genital vessel. The various systems are described in detail, and their resemblances to those of other annelids are indicated. This new species, Poeobius meseres, is made the representative of a new family, the Poeobiidae, which, provisionally at least, is included in the Echiuroidea.
Variation in spermiogenesis in the teleost family Cottidae
Authors: Hann Harry W.
Published: February 2005

In the family Cottidae there is a greater variation in the shape of the sperm than has been found, with one exception, among all the remainder of the teleosts. There is an oval and a slender type of sperm with intergrading forms. The oval and the slender types vary, so that there is a more or less complete gradation from a nearly round, disc‐shaped sperm to a slender, flattened sperm.

Spermatid masses have been found only in some of the oval sperm forms. They have been found in seven species and subspecies of the genus Cottus and in three other genera of the family, but have not been found outside of the Cottidae. They occur in widely separated places, such as Norway and China, and in both fresh‐ and salt‐water forms. In Cottus bairdii they are not found in all localities, their presence apparently being due to some external factor, perhaps temperature. It is highly probable that further investigation will show that in other species of the family, also, spermatid masses are present in some localities and not in others.
Golgi bodies, vacuome, and mitochondria in the salivary glands of the Chironomus larva
Authors: Beams H. W. , Goldsmith J. B.
Published: February 2005

Our observations confirm the recent findings of Krjukowa ('29) on the specific character of the Golgi material in the salivary glands of the Chironomus larva and are therefore in disagreement with the findings of Parat and Painlévé ('24).

The Golgi material in the salivary glands of the Chironomus larva is present as discrete bodies having the form of crescents, rings, and rods. These are evenly deposited throughout the gland and show no makred variation in number at different stages of the physiological activity of the gland.

The mitochondria are present in the form of filaments frequently concentrated in the area surrounding the nucleus and at the periphery of the cell.

Neutral‐red staining was never observed to color the Golgi bodies. It is suggested that the neutral‐red bodies may represent the secretory material. However, it is clear that, whatever the significance of the neutral‐red bodies, they are not Golgi material. Accordingly, this evidence supports the view that the Golgi apparatus, mitochondria, and neutral‐red bodies are morphologically distinct structures in the cells of the salivary glands of the Chironomus larva.
The origin of the germ cells in Amblystoma maculatum
Authors: McCosh Gladys K.
Published: February 2005

This study is based upon a close series of ontogenetic stages from cleavage until after metamorphosis.

The so‐called primordial germ cells, first differentiated in the lateral mesoderm, are traced to a definitive position in the genital anlagen. Careful counts of these demonstrated that they exist in larger numbers in the younger stages and that few of them ever reach the genital anlagen where they may form a small portion of the propagative cells.

Evidence is presented that the majority of the germ cells are of somatic origin. From the earliest appearance of the indifferent gonad certain cells in the germinal epithelium have been observed which were increasing markedly in size and undergoing the various changes necessary in the transformation of small cuboidal or spindle‐shaped peritoneal cells with oval nuclei into large germ cells with immense polymorphic or lobate nuclei. These cells are abundant in all older individuals. All the successive stages in the evolution of a somatic cell into a reproductive cell, involving as it does an increase in size, changes in shape, and a new distribution of chromatin material, are demonstrated.
An investigation of the nervous system as a possible factor in the regulation of ciliary activity of the lamellibranch gill
Authors: Lucas Alfred M.
Published: February 2005

Certain variations of ciliary activity in the lamellibranch gill occur which are an intrinsic part of the gill tissue and which are due to causes other than environmental changes. Experimental and morphological evidence indicates that the central nervous system is not involved in the production of these variations.

A comparative study of laterofrontal and lateral ciliated cells leads to the conclusion that the coordination impulse passes through the cytoplasm of the cell and that the velocity of the propagation wave is influenced by the number of cell walls per unit length through which it passes. It is suggested that the ciliary rootlets in the laterfrontal cells, due to their arrangement bring the impulse simultaneously to both rows of cilia within a single cell.
The distribution of the branchial nerve in Mytilus edulis and its relation to the problem of nervous control of ciliary activity
Authors: Lucas Alfred M.
Published: February 2005

The branchial nerve of Mytilus edulis, traced by means of serial sections, has been found to be limited entirely to the epithelial and connective tissues bordering the axis of the gills. Most of the numerous branches which originate from the branchial nerve extend posteriorly and lie close to the interfibrillar matrix of the connective tissue which supports the epithelium of this region. Fibers of these nerves have been traced to this epithelium.

The chitinous supporting structures of the gills lie in close proximity to these nerves, yet neither nerves nor nerve fibers have been observed to penetrate them. Moreover, a careful study of the gill tissues fails to reveal the presence of structures which might be interpreted as nerves or nerve fibers.

Since no innervation of the gills has been demonstrated, it seems probable that the ciliary activity of the gill epithelium is not regulated by means of fibers connected with the central nervous system.
The effects of vitamin‐E deficiency on the development of the chick
Authors: Adamstone F. B.
Published: February 2005

In an investigation of the hatchability of eggs from hens fed on a diet deficient in vitamin E Card found that all embryos from these eggs died during development. Study of these chicks showed that a variety of conditions were responsible for death:

During early development the rate of growth and differentiation was definitely slower than under normal conditions, but malformations were rare. Some embryos died during the first two days, due to disintegration of the circulatory system or its failure to become established. At the end of the fourth day there was a definite critical period which few specimens survived and by this time distinet pathological conditions had arisen in extra‐embryonic structures. These involved wiping out of the vitelline circulation by establishment of a lethal ring in the blastoderm. This structure was produced by intensive cell proliferation in the mesoderm which resulted in choking out vitelline blood vessels and their subsequent degeneration. It also caused obliteration of the exocoele, with consequent failure of the allantois to expand. In addition, many embryos showed profuse haemorrage into the exocoele. The source of bleeding was most frequently in the atrium of the heart, and at the actual rupture peculiar cells occurred which were probably histiocytic mesenchyme cells.

Although death was due directly to causes enumerated above, the ultimate responsibility rests upon conditions set up by them, namely: starvation, asphyxiation, and loss of the medium (blood) by which to carry on metabolic exchange.
Keimbahn determinants and continuity of the germ cells in Sphaerium striatinum (Lam.)
Authors: Woods Farris H.
Published: February 2005

During oogenesis granular mitochondria become concentrated in the proximal portion of the oocyte and remain concentrated in the line of cells that gives rise to the germ cells. Two cells of characteristic structure, appearing at gastrulation one on either side in the mesoderm, contain this mitochondrial cloud. All functional germ cells seem to be lineal descendants of these two primordial germ cells. The cloud disappears during gonad formation, but reappears in oocytes of the next generation. Except during meiosis and fertilization the germ‐cell cycle is traceable from fertilized egg to sexual maturity. Details of meiosis and chromosome number were not ascertained.

Capacity for producing germ cells in Sphaerium is traceable from a definite region in the egg to primordial germ cells through a localized cloud of mitochondria in the mature ovum and certain cells of cleavage stages. Mitochondria, therefore, serve as a Keimbahn determinant in the sense that they mark a region of oocyte cytoplasm destined for cytoplasm of primordial germ cells. They are not considered causal factors in production of germ cells, but are probably storage products persisting unused in the egg and in cleavage cells having lower metabolic rates. Disappearance of these mitochondria during gonad formation is explained by their dispersal among a number of cells and by their utilization in furnishing energy and material for production of new cells.
A microscopical study of glochidial immunity
Authors: Arey Leslie B.
Published: February 2005

Glochidial cysts on the gills of immune fishes form in the same manner as normal ones, but they tend to grow larger and become more irregular. The increased thickness is due to additional cellular connective tissue in the wall. The gill tissue indicates the existing biological incompatibility only by the presence of eosinophiles, extruded chromatin spherules, and eosinophilic plastids.

In natural, or racial immunity many glochidia are promptly destroyed by cytolysis, accompanied by an invasion of host cells. These disintegrating glochidia may occur in close proximity to unaffected glochidia and apparently are merely less resistant individuals that succumb to a critically adjusted reaction.

In both natural and acquired immunity the normal retention of glochidia and the accompanying metamorphosis are replaced by premature shedding. After the first day, the cyst thins by the removal of stroma cells back into the filament until the wall is reduced to a thin envelope. Both intact and destroyed glochidia, and apparently their cyst coverings, are sloughed at about the second day. Repair of the resulting notched filament is prompt.
The effects of x‐rays on regeneration in Tubifex Tubifex
Authors: Stone Raymond G.
Published: February 2005

Posterior regeneration in Tubifex is inhibited by suitable radiation with x‐rays. Only a small knob is formed at the cut surface by rearrangement of the terminal region of the old body tissues. Location of the cut within the segment and repeated removals of segments within the posterior three‐fourths of the body do not change this result. The worms are as though ‘castrated’ against regeneration. Normal worms regenerate readily under similar conditions and replace lost segments within thirty‐five days. Mesodermal tissues in normal regenerating Tubifex are formed from neoblasts, which arise from peritoneal cells upon the posterior faces of septa near the cut, migrate to this wound surface, and differentiate into new structures. After radiation no neoblasts arise from peritoneal cells and there is no mesodermal regeneration. No changes, other than failure to form neoblasts, can be observed in the peritoneal cells. Migrating neoblasts are destroyed within a few hours by similar radiation.

Epithelial tissues are also affected by x‐rays, as shown by absence of mitoses and failure of regeneration in ectodermal and endodermal epithelia. During normal regeneration cells which form these epithelia and certain muscle fibers arise by proliferation from the epidermis and intestinal lining in the regenerating region, as shown by numerous mitoses in these layers. Failure of regeneration in radiated worms is thus related to lack of cells which are present in normal regeneration.
The genitalia of the Indian mollusk Indoplanorbis exustus
Authors: Baker Frank Collins
Published: February 2005

The molluscan genus Indoplanorbis is shown to differ markedly from all other members of the family Planorbidae in the generative complex, the vas deferens being encased in a long, flexible tube in which it is freely movable. The preputium of the male complex is shown to be completely evertible from the male opening and to act as a male copulatory organ. The presence of a single, heavy penial retractor innervated by an equally strong nerve is indicated. Comparisons are made with the genitalia of the European Coretus and the American Helisoma showing fundamental differences in the generative apparatus of the three groups. Indoplanorbis is most closely related to Coretus, the vas deferens of that group being also encased in a tube. Helisoma differs from both of these genera, the vas deferens not being encased in a tube and is of the same diameter throughout its length.
The homologies of the flexor and adductor muscles of the thigh
Authors: Haines R. Wheeler
Published: February 2005

The literature relating to the flexor and adductor muscles of the thigh and their nerve supplies, in Sphenodon, the lizards, crocodiles and mammals was correlated and new dissections made of animals belonging to the last three groups. All of these muscles can be traced as individual entities from animal to animal without loss or addition to their number, although splitting may occur. The attachments of the muscles and their relationships to one another and to the two heads of the gastrocnemius are the same in all the reptiles studied. In the mammals one group, including the adductor longus and magnus and the retractor femoralis, has migrated from the tibia between the two heads of the gastrocnemius onto the femur, and another from the ilium onto the vertebrae, the one migration being caused by expansion of the gastrocnemius, and the other by expansion of the gluteal muscles. A new lateral flexor mass has been formed from part of the reptilian ilio tibialis by migration down the fibula. The nerve supplies of the various muscles are not constant when traced from group to group, and it is suggested that a muscle receives its nerve supply from the nerve nearest to it in embryonic development, so that when a muscle has migrated the nerve supply is no longer a reliable guide to its homology.
The cytology of the corpora lutea of the ewe
Authors: Warbritton Virgene
Published: February 2005

The cytology of corpora lutea of non‐pregnant ewes is described with reference to the origin, structure, fate, and function of these organs. The lutein cells, characteristic of corpora lutea, are derived from the cells of the stratum granulosum of the Graafian follicle; connective‐tissue cells, embryonic cells, and non‐striated muscle cells, from the theca interna; and erythrocytes, leucocytes, and histiocytes, from the blood stream. The lutein cells undergo changes in size, nuclear structure, and cytoplasmic inclusions correlated with the period in the estrous cycle and disappear during retrogression. Although secretory products have not been identified, a secretory function is postulated on the basis of the structure of the cell.
The idiochromosomes of an earwig, Labidura riparia
Authors: Asana J. J. , Makino Sajiro
Published: February 2005

The diploid number of chromosomes of a species of Indian earwigs, Labidura riparia, is fourteen; six pairs of autosomes with X and Y idiochromosomes for the male; six pairs of autosomes with X and X for the female.

The chromosome distribution is normal, and constant for all the individuals studied.

X and Y are derived from a single chromatin nucleolus of the early growth period which assumes a clavate form later, and remains in the same form till the metaphase of the primary spermatocyte is reached.
Development of the sense organs of the larva of Botryllus schlosseri
Authors: Grave Caswell , Riley Gordon
Published: February 2005

A study of the development of the sense organs of the larva of Botryllus schlosseri to determine, if possible, any homologies between its sense organs and those of other types of ascidians such as Molgula and Ammaroucium, which have sense organs structurally very different.

The statolith appears in the Botryllus embryo as a single club‐shaped cell. The lightsensitive organs have their primordia slightly later as five small filaments, each developed from a ganglion cell. A cavity appears in the statolith into which the light‐sensitive filaments penetrate. Later development is concerned with pigmentation of the statolith, and a twisting process which orients it into the position in which it is found in the free‐swimming larva. The three tactile papillae develop from evaginations of ectoderm at the anterior end of the embryo. The ectodermal cells at the center of a papilla are differentiated into rod‐shaped sensory receptors and ganglion‐like masses of nerve tissue. Nervous connections are established between these peripheral ganglia and the central nervous system.

Results of the investigation indicate that the statoliths of the different ascidian larvae are homologous; the direction eyes probably are not, but have evolved independently from a light‐sensitive area in the primitive larva of a common ancestral ascidian. The larvae of Molgula and Ammaroucium possess no structures comparable to the sensory papillae of Botryllus.
The development and structure of the eyes, ocelli, of the female black scale, Saissetia oleae bern
Authors: Marshall William Stanley
Published: February 2005

The female black scale possesses a pair of lateral ocelli. Each develops as a small disc of enlarged hypodermal cells which increases in size and invaginates. The disc finally becomes cut off from the hypodermis to form a vesicle lying between the regular hypodermis and the lateral margin of the brain. The vesicle becomes differentiated into two parts. The outer group of cells forms the vitreous body, the inner group gives rise to the retina. The vitreous body soon begins to secrete the lens which, during embryonic life, becomes biconvex. Pigment granules form only in the retinal cells; at first yellow, later black. The ocellus of the first instar is similar to that of the embryo. During first and second ecdyses the old lens is cast off and a new one secreted by the vitreous body. A large, irregularly shaped crystalline body forms between the vitreous body and the retina. The ocellus is of four parts: lens, vitreous body, crystallin body and retina. Retinal cells are at first nucleated but the nuclei probably pass to the nerve fibers each one of which is connected to a retinal cell. The ocellus does not change in structure throughout the life of the insect but finally disintegrates. The disintegration begins on the inner surface of the lens. Ocelli developed in the embryo remain unchanged throughout the insect's life.
The microscopic structure of the shell and ligament of cardium (cerastoderma) corbis martyn
Authors: Mitchell Harold D.
Published: February 2005

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.
The myology of salamanders with particular reference to Dicamptodon ensatus (Eschscholtz). I. Muscles of the head
Authors: Eaton Theodore H.
Published: February 2005

This paper is the first of a series of four describing the anatomy and development of the muscles of Dicamptodon ensatus (Ambystomidae) and comparing them in detail with those of other genera and families of Urodela. In the present paper the muscles of the eye, jaw and hyobranchial apparatus are included, with the exception of the few longitudinal throat muscles derived from trunk myotomes; the second paper will include those of the trunk and tail and their derivatives; the third, those of the limbs and the fourth, a discussion of developmental principles in myology and the bearing of muscles upon classification and phylogeny in the salamanders. The correlation of data on various larval, perennibranchiate and adult forms reduces many muscle names to synonymy, and simplifies the understanding of certain difficult parts of the anatomy. Less attention is given to innervation than to developmental changes and the derivation of the muscles. Dicamptodon, in the larval stage, typifies other larval and most perennibranchiate forms, at metamorphosis it shows the most generalized methods of muscular and skeletal transformation, and when adult the animal serves as a landmark for recognizing the directions of evolution among other Urodela.
Germ cell origin and spermatogenesis in the Siamese fighting fish, Betta splendens
Authors: Bennington N. L.
Published: February 2005

Residual germ cells larger than primary spermatogonia but similar in other respects are found throughout the testis in the walls of the lobules and in the cysts of developing germ cells. There is no evidence for germ cell migration through the testis. Spermatogonia arise in situ from residual cells.

Forty‐two chromosomes are found in the spermatogonial cells. Two of these chromosomes are much larger than the others and possibly represent sex chromosomes. The haploid chromosome number as seen in primary spermatocyte cells is twenty‐one. A large ovoid chromosome, considered to be a sex chromosome, lags during the formation of the primary spermatocyte spindle. It divides after the division of the other chromosomes into equal chromosomes which pass to opposite poles of the spindle.

The evidence for sex chromosomes as presented here is meagre but is consistent with the evidence from chromosome studies in other teleosts. It has been proposed that sex chromosomes are in a nascent condition and hence are differentiated but little from autosomes and also that the members of the sex chromosome pair are morphologically alike.
Phylogeny of the distal musculature of the pectoral appendage
Authors: Howell A. Brazier
Published: February 2005

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.
Panniculus carnosus and formation of the pouch in Didelphids
Authors: Enders Robert Kendall
Published: February 2005

Panniculus carnosus is well developed in the five Didelphids studied. It is described in three parts: pars dorsalis, pars thoracoabdominalis and pars pudenda, in Marmosa, Didelphis, Metachirops, Metachirus and Chironectes, and in Orolestes, a caenolestid marsupial. Pars dorsalis is well developed in all five genera, but not so well developed as in Orolestes; pars thoracoabdominalis is present in all five Didelphids, but not in Orolestes; and the degree of development of pars pudenda is correlated with the development of the pouch, being absent in Orolestes, weak in Marmosa and strong in both males and females of the other genera. In Chironectes, in which genus the male develops a pouch, pars pudenda is strikingly developed. The ‘sphincter marsupii’ of other writers is considered to be a portion of pars pudenda.

In early development an epidermal ridge arises surrounding part of the mammary area. In Marmosa these ridges move laterally and posteriorly before the expanding mammary area. In Didelphis, Metachirops, Metachirus and Chironectes the ridges form the lips of the pouch. The pouch is formed when the ridges remain stationary and the expanding mammary area throws the skin into a double‐walled fold.
Morphology of Campeloma rufum, a parthenogenetic snail
Authors: Mattox N. T.
Published: February 2005

Collections of Campeloma rufum were made at all seasons of the year from the Salt Fork River at Homer Park, Illinois, for gross anatomical and histological studies. No males nor male reproductive cells were found, all individuals showing definite female structures. The gonad, found on the columellar surface of the digestive gland, shows ovarian cells. A U‐shaped tube from the albumen gland to the uterus receives the oviduct near its proximal end. This duct leads into a glandular pocket, the shell gland, which in turn empties into the sac‐like uterus. The uterus terminates near the edge of the mantle in a muscular vaginal tube. The previously undescribed kidney, a glandular, pyramidal organ, lies posterior and to the left of the upper end of the mantle cavity. The kidney possesses two orifices opening into the pericardium and ureter respectively. The ureter opens between the vagina and the anus. Intra‐uterine young were observed during all seasons of the year varying progressively from small veliger to fully formed young. A later paper on oogenesis, will attempt to substantiate parthenogentic reproduction for C. rufum.
The embryology of the guinea pig. II. The polydactylous monster. A new teras produced by the genes PxPx
Authors: Scott J. P.
Published: February 2005

A detailed study of Wright's polydactylous monster (produced by a semi‐dominant lethal gene) indicates that it belongs to a general type found also in rare human cases. The diagnostic characteristics are: clubbed feet and approximately double the usual number of digits, embryonic posture, microphthalmia and enlargement of the diencephalon, and missing tibia and telescoped sternum; all organ systems in the body except the genital and circulatory are grossly abnormal. The defects appear to be produced by an arrest of morphogenesis and an alteration of relative growth rates. It is indicated that a controlling center of digit formation exists on the lateral (postaxial) side of the foot, that skeletal and dermal structures are controlled by it, but that muscles are differentiated according to the area of the limb in which they lie. The gene itself is not atavistic, although its effects in the heterozygote have that appearance.
Adaptations for viviparity in embryos and ovary of Anableps Anableps
Authors: Turner C. L.
Published: February 2005

In the Anablepidae, a family of viviparous Cyprinodont fishes, the mature eggs are fertilized in the ovarian follicles. The embryos are retained in the modified ovarian follicles until birth and are born when about 44 mm. in length. The embryos develop expanded yolk sacs which reach a maximal diameter of about 10. mm. The vitelline veins on the surface of the yolk sac develop rows of bead‐like swellings, yolk sac bulbs, which serve to facilitate absorption of materials from the fluid of the follicle cavity. There is an extensive system of follicular villi upon the internal lining of the follicular capsule, the apparent function of which is to increase the vascular surface of the internal lining of the follicular capsule and to facilitate the interchange of materials between the blood of parent and fluid of the follicular cavity. The follicular villi and the yolk sac bulbs develop at the same time. These two adaptations for viviparity are apparently unique in this family of fishes.
The microscopical anatomy of metamorphosis in a haploid salamander, triton taeniatus laur
Authors: Fankhauser Gerhard
Published: February 2005

The microscopical examination of the first haploid salamander to live through metamorphosis shows that the transformation to a terrestrial vertebrate was normal and practically completed at the time of its death. All the organs and structures that develop shortly before and during metamorphosis and are typical for the adult salamander, e.g., the integument, the pharyngeal derivatives, and various glands of special function, are present.

The nuclei in all organs and tissues of the haploid animal are smaller than normal. This is indirect evidence of the uniformly haploid condition of the animal. The majority of the organs are smaller than in the control but contain a larger number of cells. In some glands, the reduced cell size has been completely compensated by the increase in cell number.