bluuebunny/crossref_metadata_2025 huggingface dataset:
Chromosome studies. V. Diploidy and persistent chromosome relations in partheno‐produced Tettigidae (Apotettix eurycephalus and Paratettix texanus)
Authors: Robertson W. R. B.
Published: February 2005

Number of chromosomes is 13 (♂) and 14 (♀), the same as in biparentally produced relatives. In diploid groups from partheno‐produced individuals homologous chromosomes tend to lie together, as ‘doubles’ or separated but near each other. In biparentally produced individuals they have as marked a tendency to lie in oppósite halves of the plate. Chromosomes of an individual tend to persist in the same position from cell to cell in the partheno‐produced, with homologues side by side arranged about one center; in the biparentally produced, with seven single members arranged about each of two centers. In the partheno‐produced the cells of younger animals, or of the earlier stages of organs in older animals, have a larger proportion of ‘double’ chromosomes or closely associated homologues.

These conditions suggest that the partheno‐produced individual arises from an egg with a single pronucleus in which there were seven ‘double’ or diad‐like chromosomes, and the biparentally produced from an egg with two pronuclei, each with seven ‘single’ chromosomes. The paired position of homologues in Diptera may be due to synapsis‐like tendencies in early cleavage, either as ‘hang‐over’ effects from the preceding meioses or a different type of synapsis mechanism in Diptera. Partheno‐produced male tettigids may be accounted for through non‐disjunction among the four parts of the sex tetrad.
The aortic arches and their derivatives in the embryo porcupine (Erethizon dorsatus)
Authors: Struthers Parke H.
Published: February 2005

This ontogenetic study shows the following facts: (1) the presence of a vidian artery homologous with that of reptiles, which serves visceral elements of the jaw; (2) there exists a transitory occipital artery arising from the stapedial which contributes to the vascular supply of the occipital region; (3) the presence of a transitory fifth arch intimately associated with the sixth arch; (4) there is evidence of at least two presegmental branches of the aorta; (5) in the development of the adult pulmonary stem the right artery forms very little of the common vessel; (6) a single cephalobrachial trunk forms the culmination of arch development; (7) arterial development of the head and neck falls into three phases: (a) a temporary arterial pattern designed to carry nutriment to primitive head structures, (b) a plan of arterial distribution adapted to supply the rapidly forming cartilage and muscle of the jaws, and, (c) a readjustment period when the arterial plan is readjusted due to the increased heteronomy of the head.
A study of living sperm cells of certain grasshoppers by means of the ultraviolet microscope
Authors: Lucas Francis F. , Stark Mary B.
Published: February 2005

This paper discusses very briefly the ultraviolet microscope and the developments which have led to a successful technique for optically sectioning living cells; also the ultraviolet photomicrographs of living sperm cells of certain grasshoppers, which show clearly the spinning out of the chromonema from solid blocks of the diatene stage, the pairing of same in the leptotene stage, the development of the tetrads, the final distribution of the chromosomes in the resulting spermatids and their return to a spiral chromonema, each inclosed in its own vesicle. The details of the cytoplasm are equally well brought out.
Some histological effects of ultrasonic waves on cells and tissues of the fish lebistes reticulatus and on the larva of rana sylvatica
Authors: Chambers L. A. , Harvey E. N.
Published: February 2005

Some pathological effects of supersonic waves produced by the piezo‐electric oscillator described by Wood and Loomis ('27) are described.

Death of fish and frogs was due to haemolysis of erythrocytes within the gill capillaries. Disruption of gill filaments, trauma, and extravasation in the head and gill region and in the peripheral musculature were noted.

No effect on the nervous system was apparent histologically.

Organisms were not killed in water under hyper‐ or hyponormal pressures. In these cases no cavitation of gases took place.

Isolated frog sartorius muscle in Ringer's was not damaged.

Bubbles of gas were easily observed within the muscle cells of the tadpoles when such cells were not more violently disturbed. Such bubbles were abundant in the more fluid muscles of four‐ or five‐day tadpoles, less abundant in 15‐ to 35‐mm. Lebistes, and entirely lacking in adult frog sartorius. Protoplasmic viscosity differences probably explain the gradient.

The above‐observed intracellular cavitation explains the muscular destruction, the haemolysis, the change in specific gravity of organisms subjected to the wave treatment, and may offer light upon the stimulatory effect of such waves on excitable tissues (compare Harvey, '28).
Thermal relationships in the neutral‐red reaction
Authors: Koehring Vera
Published: February 2005

Neutral‐red staining in Daphnia, legume seeds, starfish eggs, and Palaemonetes shows reactions to temperature changes which may be correlated with the thermal reactions of enzymes.
A demonstration of the vacuome and the golgi apparatus as independent cytoplasmic components in the fresh eggs of teleostean fishes
Authors: Nath Vishwa , Nangia Murli Dhar
Published: February 2005

The most important conclusion of this investigation is that the vacuome and the classical Golgi apparatus are independent cell components in the oocytes of Ophiocephalus and Rita. The same conclusion has been arrived at by Nath in Rana tigrina. The vacuoles, the Golgi elements, and the mitochondria can be seen intra vitam side by side.

In Ophiocephalus the vacuoles give rise to albuminous yolk, as has been rightly claimed by Hibbard for Discoglossus and by Hibbard and Parat for Perca and Pygosteus. The Golgi elements give rise to the fatty yolk as in so many other forms of oogenesis described by Nath and others.

In Rita the fate of the vacuoles and the Golgi elements is unknown, as the fish suddenly disappeared from the Ravi during the spawning period.
Spermatogenesis in sturnus vulgaris: Refractory period and acceleration in relation to wave length and rate of increase of light ration
Authors: Bissonnette Thomas Hume , Wadlund Arthur Pehr Robert
Published: February 2005

Between December 10th and January 24th, using red, green, and white electric lights at equal intensities of about 1.7 foot‐candles, sixty‐nine males, with females, were subjected nightly to, (a) constant six‐ and six‐and‐one‐quarter‐hour periods of illumination; (b) periods increasing gradually from one‐quarter to six and one‐quarter hours; (c) no added light (controls), in a basement room lighted by day from three large windows. Relative heat intensities reaching the birds were: for white, 1; for green, 2.5; for red, 10.

Birds were killed for testis study at 5, 12, 16, 22, and 23 days.

Refractory period was shorter, and modification of spermatogenic activity much greater, under a than under b types of treatment, as compared with controls. Effects were also more consistent.

Descending order of testis activity induced at all stages was red, white, control, green, under both a and b.

Effects on testis activity are not proportional to heat intensity of incident light, but depend on wave length, since green effect is not intermediate between those of white and red, as its heat intensity is. Green inhibited germ‐cell activity even in birds already at normal midwinter minimal condition.

Constant six‐hour red‐light treatments, of this intensity, induced flrst appearance of metamorphosing sperms in twenty‐three days in midwinter.

Apparatus and mode of light regulation and measurement are described.
Chromosomes of three species of mantidae
Authors: King Robert L.
Published: February 2005

There are twenty‐seven spermatogonial chromosomes in Tenoder'a sinensis, three of which are larger than the others and lag behind in anaphase. These three chromosomes have been traced through the prophases of the first spermatocyte to the metaphase, where they appear as a hexad. In the first spermatocyte division two of the constituent diads of the hexad pass to one pole, the remaining one to the other, thus giving rise to two types of second spermatocytes, one with thirteen and the other with fourteen chromosomes. There are twenty‐eight chromosomes in somatic metaphases of the female; four of these chromosomes are larger than the others. The sex chromosomes of the male are represented by the formula Xa + Y + Xb, that of the female by 2Xa + 2Xb.

Similar conditions are reported for Mantis religiosa and Stagmomantis carolina.
Developmental stages of the chondrocranium in some selachians
Authors: Harrison Bruce M.
Published: February 2005

Serial sections of seven embryos were examined, in four of which the chondrocrania were reconstructed. Parachordals appear as independent precartilages on each side of the notochord in the otic region. Later chondrification occurs, and they fuse with the notochord. Orbitals and trabeculae appear as independent precartilages; later, as cartilages they fuse with the basal plate and with each other, forming the cranial wall between the orbital cavity and brain. An apparent shifting posteriorly of the bases of the fifth, seventh, and eighth cranial nerves, in respect to the anterior end of the notochord and to the otic vesicles, occurs between the 10‐mm. and the 60‐mm. stages. The otic vesicles, proportionately small in the 10‐mm. stage, reach their relatively largest size in the 19‐mm. embryo. The floors of the otic capsules begin as lateral extensions of the basal plate at the 25‐mm. stage, and from these anlagen chondrifications extend, forming the anterior and posuerior cupolas. Most of the tegmen cranii forms by chondrifications that approach the median plane from each side. It is practically complete in the 60‐mm. embryo. The cervical neural arches also contribute in forming the tegmen cranii and the occipital region. The ventrally recurved end of the notochord of the 10‐mm. stage persists through the 60‐mm. embryo.
The early develoment of the duck's egg, with special reference to the origin of the primitive streak
Authors: Chen Beh Kang
Published: February 2005

This study deals with the development of the duck embryo from the unincubated blastoderm to the 1‐to‐3‐somite stage. In the unincubated stage the thickened posterior germ wall is the most active region mitotically, contributing cells to complete the entodermal layer. The slightly thickened ectoderm of the posterior half of the pellucid area is the precursor of the embryonic shield. During incubation this ectoderm increases in height, forming the embryonic shield. The primitive streak arises in the posterior part of the shield, where tall ectodermal cells in the midline become several‐layered and proliferate cells from their ventral surface which migrate laterally, becoming mesoderm. At first short and broad, the streak becomes longer and narrower until it attains its definitive stage.

The greatest proliferation of ectodermal cells occurs always at the anterior end of the streak of all stages, forming at the definitive stage a definite thickening–Hensen's node. Proliferation diminishes posteriorly along the streak.

The number and orientation of mitotic figures indicate cell movements as follows: Prestreak stages–ectodermal cells migrate from posterior part of shield toward midline, thence forward in midline; early streak stages–anterior movement in streak and to sides of streak, and lateromedial movement from sides toward middle of streak; definitive streak stages–postero‐anterior and lateromedial migration of cells.

The embryonic axis, of prestreak and streak stages, lies approximately at right angles to the egg axis in slightly over 50 per cent of the cases.
The structure of opalinids, as revealed by the technique of micro‐incineration
Authors: Scott Gordon H. , Horning E. S.
Published: February 2005

Opalinids from the rectum of Rana pipiens were isolated in large numbers and fixed in a mixture of nine parts of absolute alcohol and one part of neutral formalin. These were embedded in paraffin and incinerated according to the technique of Policard. Examination of the preparations by dark‐field illumination showed that the micro‐incinerated protozoa retained their distinctive morphological and cytological characters, for the mineral ash had the same topographical distribution as the cell inclusions in the control stained preparations.

The coarse vegetative granules of the cytoplasm were preserved as distinct masses of ash which corresponded exactly to these bodies in the control preparations. The structure of the myonemata and the cilia was perfectly preserved. The chromatin material of the nucleus, more or less abundant, left little or no ash, which is quite in contrast to the findings of Scott with regard to amphibian and mammalian nuclei.
Polyploidy and metaphase patterns
Authors: Wilson Edmund B.
Published: February 2005

A cyst of tetraploid first spermatocyte metaphases is described in the coreid hemipter Archimerus alternatus (Say), all other divisions in the testis being of normal diploid constitution. The striking fact is that in spite of the doubling of their number the chromosomes closely follow the group pattern characteristic of the corresponding normal divisions. In the latter the first metaphase always shows a ring of six autosome bivalents with a single m‐chromosome bivalent at its center and a single univalent X‐chromosome lying outside the ring (as in coreids generally). In corresponding tetraploids the numbers are respectively 12, 2, and 2. Three additional interesting features of the tetraploids are: 1) the fact that the two m‐bivalents are always lined up end to end to form an axial quadrivalent chain; 2) that although two X‐chromosomes are present (as in the normal female), they are never united to form a bivalent as in that sex; and, 3) that in the prophases (of which a few are present in the cyst), at least one pycnotic X, or chromosome nucleolus, is present.

A critical discussion is offered of the general problem of the mechanism of chromosome movements and groupings, together with a review of recent literature. The conclusion is urged that the chromosomes themselves play an active and important part in these processes, and the possible genetic relations between chromosomes and spindle substance are discussed.
Embryology and life history of chaetopleura apiculata
Authors: Grave B. H.
Published: February 2005

The breeding season of Chaetopleura apiculata begins about June 20th to June 25th and continues until about October 1st. Spawning takes place in the early evening, 8 to 11 O'clock. The cleavage and early development are strikingly similar to that of Ischnochiton as described by Heath, and is typically molluscan. The egg is enclosed in a bristly chorion from which it hatches after twenty‐five to thirty hours. The larva is a large opaque trochophore which gradually transforms into a veliger larva by the development of the shell and foot. It settles to the bottom and metamorphoses into the adult form after six to ten days. It becomes sexually mature in one year and is full grown in three or four years, when it measures 29 × 18 mm. or less.
Morphogenesis of the brain
Authors: Herrick C. Judson
Published: February 2005

The fundamental structure of the brain stem is uniform throughout the vertebrate series, not essentially because it expresses an architypical pattern, but because of the constancy of peripheral connections and their internal relationships, both of which are parts of an apparatus of adjustment to environment which is common to vertebrates. Other parts of the brain are more variable because, with complication of the behavior pattern in higher forms, more elaborate and diversified mechanisms of correlation and integration are requisite.

The brain stem between the olfactory bulb and other primary sensory centers is plastic tissue not dominated by any single sensory‐motor system; it is the meeting place of descending and ascending sensory paths. Here the chief apparatus of correlation and integration is elaborated. From it emerge the complex thalamic and cortical adjustors. The pallium is not a primary constituent of the vertebrate brain. The pallial type of organization gradually emerged from the more ancient subpallial type and comes to mature expression in the cerebral cortex. Several instructive stages in the progressive differentiation of cortical structure and connections are seen in the amphibian forebrain, but the process is not consummated. Amphibia have no cerebral cortex, though cortical primordia are evident here and in various fishes. Static concepts of architypes and the dialectic of ‘form‐analytic’ argumentation are replaced by a more dynamic treatment of morphogenesis.
The structure of the testis and movement of sperms in chortophaga viridifasciata as demonstrated by intravitam technique
Authors: Payne M. Anthony
Published: February 2005

By means of the ‘intravitam technic’ developed by Baumgartner and Payne (1931), the mature or maturing sperm of Chortophaga viridifasciata have been traced from the follicle of the testes in the male to the locus of fertilization in the female. The sperm aggregated into bundles, and held tight by a hyaline cytoplasmic cap, spiral up the follicle, turn and spiral back to the vas deferens by means of a periodic lashing and writhing of the sperm tails.

The genital tract is described briefly. In the vasa deferentia and storage tubules, the sperm bundles are usually in a quiescent state, having been inactivated most probably by secretions from the tubules.

Peristalsis and currents in the fluid contents of the tubules move the inactivated sperm from the vesicles of the male to the seminal receptacle of the female, where the cytoplasmic caps gradually disintegrate. This permits individual sperm to pass down the seminal duct and fertilize the ovum just before oviposition.

Single photomicrographs and a series of photomicrographs show the sperm in various parts of the genital system and making actual progress up a follicle. A stained preparation was used for only one of the photos. The other nineteen are from living unstained tissue. The intravitam observations are, most probably, more ‘vital’ than any heretofore recorded.
An anatomical study of the furless condition in rabbits
Authors: Drapeau Elizabeth East
Published: February 2005

A histological study of Hammond's simple recessive ‘furless’ rabbits was made from many series of sections taken from the skin of both the normal and furless rabbits of several pertinent ages.

It was found that the external absence of under‐hair or fur exists because of a failure of the hairs of these follicles to erupt. This failure is due to a premature keratinization which first affects the sebaceous glands and then the inner epithelial sheath. The resulting abnormal channel allows an erratic escape, especially of the regenerating hair above the incomplete inner sheath into the surrounding connective tissue, where the escaped part of the hair atrophies. The final condition shows an inflammatory reaction in the areolar tissue here. There is no check on the growth from the bulb of the root. Other elements of the skin verify this excessive keratinization.

The cause of the abnormal metabolic changes conceivably lies in an inadequate tissue supply of oxygen or nutrition. The regulator may be the sympathetic system directly or indirectly (by hormone action), or it may be an inhibitor resident in the integument itself.
Viviparity superimposed upon ovo‐viviparity in the goodeidae, a family of cyprinodont teleost fishes of the Mexican Plateau
Authors: Turner C. L.
Published: February 2005

The Goodeidae are a family of cyprinodonts containing about nine genera and twenty‐six species. They are confined exclusively to the Mexican Plateau and to streams in the immediate vicinity. All are viviparous. Fertilization is internal. The eggs are extremely small and contain very little yolk. The embryos are retained in the ovarian follicles until the yolk is practically absorbed, in the meantime developing unique absorptive organs in the form of extensive ribbon‐shaped proctodaeal processes. The embryos are evacuated into the intra‐ovarian cavity where they are retained for several weeks, during which time the proctodaeal processes become extended. The ovary becomes a nutritive organ and produces secretions which are discharged into the intra‐ovarian cavity and absorbed by the embryo through their unique processes. The processes differ in form, number, and histological structure, but are specific in their peculiarities for each species. These specific differences, together with marked differences in the ovary, will furnish a basis for a re‐classification of the genera and species of the family. A comparison in made between this family and the other ovo‐viviparous and viviparous cyprinodonts, on the basis of which it is concluded that the Goodeidae have arisen separately from an ovo‐viviparous ancestor, which in turn was derived from an ovo‐viviparous type. A comparison is also made between the peculiarities of reproduction in this family and those of other viviparous teleosts.
Localization of mineral ash in the organelles and cytoplasmic components of paramecium
Authors: MacLennan R. F. , Murer H. K.
Published: February 2005

Paramecium caudatum was studied by micro‐incineration, by stained control sections, by vital staining, and by osmic impregnation. It was found that a slow initial heating and a slow cooling after incineration greatly reduce the amount of distortion and shrinkage in the incinerated specimens. Most of the cytoplasmic components and organelles, including vacuome, chondriome, cilia, and basal granules, trichocysts, food vacuoles, and the nuclei, could be identified by their ash. No ash is found in the pellicle and only a small amount in the hyaloplasm. None of the osmiophilic components such as granules or the walls of the contractile vacuole could be identified in the incinerated specimens with certainty. The larger amount of ash in the endoplasm as compared with the ectoplasm is due to the large number of granules in the former region. The nucleus and some of the granules near the nucleus show traces of iron.
Studies upon regeneration. I. The constrasting powers of regeneration in planaria and procotyla
Authors: Curtis Winterton C. , Schulze Lula M.
Published: February 2005

When sexually mature Procotyla fluviatilis Leidy (commonly but erroneously known as Dendrocoelum lacteum) are cut transversely into head, pharyngeal, and tail pieces of about equal length, the head and pharyngeal pieces fail to regenerate in a large percentage of cases and tail pieces never regenerate. When regeneration occurs in head and pharyngeal pieces it is somewhat slower than in similar pieces of Planaria maculata Leidy and Planaria agilis Stringer with which comparisons were made. Cutting mature Procotyla into larger numbers of pieces usually results in death of all, although smaller pieces from prepharyngeal regions sometimes regenerate. Juvenile P. fluviatilis have greater powers of regeneration, as shown by cutting head and pharyngeal regions into greater numbers of pieces, but tail pieces do not regenerate. These observations confirm and extend those of earlier investigators. Such a restricted power of regeneration contrasts with well‐known powers in P. maculata and P. agilis. Counts of formative cells, from which new parts arise in all three species and which are regarded by the authors as a persistent embryonic stock, indicate about 8.5 such cells in P. maculata to 1 in P. fluviatilis per unit area. It is concluded that regeneration in planarians is correlated with numbers of such formative cells and that histological factors are no less important than physiological ones. The paper is preliminary to a study of effects of x‐rays upon regeneration.
Staining reactions of protoplasm and its formed components. A cytological and biochemical study
Authors: Jeffers Katharine R.
Published: February 2005

Chemical analyses of the lipoids in fresh and autolyzed pancreas of the cat have been correlated with the staining reactions of sections of this organ preserved by three cytological methods. Quantities of total fats and of phospholipins, the iodine numbers of total fats and of phospholipins, and the free fatty acid numbers were determined. None of the methods of fixation used reveals the total fat content of the tissue. The intensity of staining of material fixed by Helly's method and stained with acid fuchsin is dependent on the phospholipins of the tissue, but the exact nature of the relationship is not certain. The intensity of staining of material preserved by Champy's method and stained with acid fuchsin can be correlated with the iodine number of the phospholipins of the cells. The degree of blackness of sections preserved by the Kolatchev‐Nassonov method can be correlated with the iodine number of the phospholipins of the cells. The free fatty acid content is probably also a significant factor. The methods demonstrate lipoids qualitatively rather than quantitatively. Only physiologically similar cells may justifiably be compared by the cytological methods studied.
Somatic mitoses of Drosophila melanogaster
Authors: Kaufmann Berwind P.
Published: February 2005

The chromosomes of D. melanogaster have been followed through the entire cycle of mitosis in ganglion cells. Primary constrictions exist at about the middle of the second and third chromosomes, at a sub‐median position in the Y, at a sub‐terminal in the X, and probably also at a sub‐terminal position in the fourth chromosome. Secondary constrictions, in addition to those reported by Bridges, are sub‐terminal in the arms of the second and third chromosomes. A pronounced sub‐median secondary constriction in the left limb of the second chromosome offers a criterion for distinguishing between the second and third chromosomes, and between right and left arms of the second chromosome. The proximal secondary constriction in the X‐chromosome and that in the short arm of the Y are associated with the normal development of the nucleolus. Anaphase chromosomes are longitudinally double, the split following the turns of the chromonemata. Metaphase and anaphase chromosomes are essentially isodiametric from end to end, except at the constrictions or indentures. Somatic pairing of chromosomes reaches its maximum expression during late prophases, both in male and female ganglion cells. The four chromatids of the tightly appressed homologues open out in two planes giving distinct chiasma‐like configurations. Separation of the paired chromosomes is completed in late prophase, so that at metaphase the homologous chromosomes are not in contact.
The development of the thymus bodies in necturus maculosus
Authors: Webster W. D.
Published: February 2005

The primordia of the thymus bodies in Necturus begin to form in 7‐mm. embryos. These structures arise as clumps of entodermal cells on the posterior dorsal portion of the first four visceral pouches; the first or last pouch, being rudimentary, fails to form such a primordium. All except the first of these primordia lose their connection with their respective pouches in the 16‐mm. stage and lie free in the surrounding connective tissue. The primordium on the first pouch begins to show degenerative changes during that stage, losing connection with its pouch in the 23‐mm. stage, finally to disappear altogether in 30‐mm. specimens.

The three remaining bodies continue to grow, but the second and third outstrip the fourth in development and begin to form Hassall's corpuscles in 32‐ to 34‐mm. stages. Sections of 30‐mm. Necturi show a few of these corpuscles fairly well developed and containing a faintly staining secretion. The fourth body remains relatively small a long time, not showing the Hassallian cysts until the animal is 60 mm. long. By shifting of positions and increasing in size, the three bodies come to lie in proximity, one behind the other, to form the definitive thymus gland of the adult. The gland lies embedded in the heavy musculature on top of the head in front of the gills.
Chemoreceptors of blowflies
Authors: McIndoo N. E.
Published: February 2005

This paper deals with the morphology of all the so‐called gustatory and olfactory organs of blowflies, and describes tests conducted to determine whether these insects taste with their tarsi and smell with their antennae and palpi. Antennae bear two types of so‐called olfactory hairs, while palpi bear only one. With the aid of an olfactometer it has been shown that antennae and palpi do not bear the olfactory organs.

In order to explain the proboscis response, described by Minnich, it is not necessary to assume that tarsi bear gustatory organs, because: (1) a tarus bears no sense organs, except nine olfactory pores; (2) it is almost impossible to wet the tarsi with water or sugar water; and (3) when flies were in the proper nutritive condition and liquids were about 3 mm. from the tarsi, the insects were induced by a special method to exhibit the proboscis response. It was further clearly demonstrated by a similar method that tarsi can easily distinguish between chemically pure saccharose water and distilled water when these liquids are about 3 mm. from the tarsi. The responses, obtained by any method, are caused by two stimuli, one mechanical and the other olfactory. The act of touching the feet produces the initial stimulus and brings the liquids almost in contact with the olfactory pores on the tarsi.
Intravitam studies on the hemipteran, Leptocoris trivittatus. A description of the male reproductive organs and the aggregation and turning of the sperms
Authors: Payne M. Anthony
Published: February 2005

A study of the male reproductive organs of a hemipteron, Leptocoris trivittatus, has been made. The genital system, which consists of fan‐shaped testes; the vasa deferentia, to which a single pair of accessory glands are attached; ejaculatory ducts and the copulatory apparatus, is described and photomicrographs of consecutive parts presented.

Then an analysis of the method of aggregation and turning of the sperms is made by means of intravitam technic. Aggregation and turning commence in the early spermatid stage. A spherical cyst forms, the tails first grow centripetally and then push out toward the lower end of the cyst. This line of growth in the cyst moves the head ends of the spermatids to the upper end where aggregation gradually takes place.

The cysts spiral up and across the follicles, the moving force being, probably, the elongating tails. Later they spiral down the follicle, development progressing rapidly. The descending bundles are mature sperm, held together by a cytoplasmic cap.

The accessory gland secretes a milky substance which probably activates the sperm at a later stage. Peristalsis occurs in the wall of the gland and duct.

The process of massing sperm into bundles before copulation insures effective translocation. Then peristalsis and movement of tubular fluids carry the sperm down the duct to the copulatory apparatus.
Somatic synapsis in chironomus, with special reference to the individuality of the chromosomes
Authors: King R. L. , Beams H. W.
Published: February 2005

The nuclear band of the cells of the salivary glands of Chironomus larvae regularly consists of four segments or chromosomes. Each of these may be recognized by its characteristic distribution of chromatin discs of various sizes. When nucleolar elements are present they have a definite location in relation to the chromation discs of a certain chromosome. The diploid number of chromosomes is eight; therefore, the four segments in the cells of the salivary glands represent four pairs of homologous chromosomes in somatic synapsis which here is not a simple approximation but an accurate pairing part by part of the homologous chromosomes.
‘The Linea masculina,’ a new secondary sex character in Salientia
Authors: Liu C. C.
Published: February 2005

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.
Spermioteleosis of Bruchus quadrimaculatus, Fabr.
Authors: Mickey George H.
Published: February 2005

The cytoplasmic structures in the spermioteleosis of Bruchus quadrimaculatus were studied, using various fixatives and stains including vital and smear techniques.

Mitochondria appear in all stages following spermatogonia, exhibiting characteristic appearances during mitoses and in the spermatids. The [central substance] in the halves of the nebenkern becomes localized along the edges of the outgrowing [ribbons] as the source of the marginal filament. The undulating membrane apparently is formed by the fusion of these [ribbons.] The axial filament arises from the distal centriole, being permanently attached thereto, and lies along one edge of the undulating membrane of the tail.

Golgi bodies are first observed in the secondary spermatocyte; they behave characteristically during spermiogenesis, producing the acrosome and leaving a residuum, the Golgi remnant, to be sloughed off with the cytoplasm from the tail.

Chromatoid bodies occur in some spermatids but not in others. They migrate backward along the axial filament to be rejected with the Golgi remnant.
Color changes in Palaemonetes
Authors: Brown F. A.
Published: February 2005

The pigmentary system of Palaemonetes vulgaris contains four pigments. These are red, yellow, blue, and white. With the exception of the blue all are found exclusively within chromatophores and are capable of becoming either dispersed into chromatophore branches or concentrated into chromatophore centers. The state of dispersion or concentration of each pigment is quite independent of the state of any other pigment and is determined by the color of the background upon which the animal lies. It is by the mixing of appropriately colored pigments by dispersion of those pigments that the animal adapts itself to its background. The blue pigment appears to be in the same chromatophore with the red but its dispersal is not restricted by the confines of the pigment cells, and its disappearance from tissues seems to be a case of destruction in situ. The rates of measured in background changes. In the case of each pigment, concentration was more rapid than dispersion and the rates for the red and white pigments were approximately the same.
A comparative study of the branchial epithelium in fishes, with special reference to extrarenal excretion
Authors: Bevelander Gerrit
Published: February 2005

A study of the brinchial epithelium in representative specimens of Cyclostomata Elasmobranchii and Teleostei fishes has been made, with special reference to the following: 1) the importance of physiological role of osmotic regulation effected by the gills; 2) the presence or absence of specialized secretory tissue; 3) progressive evolution of the fishes and the possible phylogenetic difference between them. In regard to these topics we find: 1) There is no indication of any specialization in the branchial epithelium of fishes indicating a special role in extrarenal excretion. 2) In the respiratory epithelium of fishes widely separated phylogenetically or in fishes in living in fresh or salt water, the only significant differences are that in general the teleosts have a squamous type of epithelium, whereas, the elasmobranchs have in general a thicker polyhedral investment. 3) Mucous cells appear large and numerous on the filament proper, smaller and less numerous in the interlamellar spaces, and on the free surface of the lamellae. These are the only specialized secretory cells which occur in the gills.
Behavior and morphological changes in the leech, Placobdella parasitica, during hypodermic insemination
Authors: Myers Raymond J
Published: February 2005

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.
Effects of the flexed‐tailed gene on the development of the house mouse
Authors: Kamenoff Ralph J.
Published: February 2005

The flexures in the flexed‐tailed mouse consist of unilateral fusions of adjacent vertebrae. Fusions, if complete, produce straight stiff segments.

In normal mouse embryogeny, the precartilage cells surrounding the developing nucleus pulposus of the embryonic intervertebral disk in the proximal tail region begin to elongate and become fiber‐like at about 14 days after fertilization. In the flexed mouse, such differentiation fails to take place on one side of an affected disk, and these cells develop through cartilage to bone. At such a point there is frequently a bend in the notochordal axis. Other abnormalities of the notochord have been observed. These are not the cause of the flexures.

The gene for flexed tail also produces two effects more general in their expression. First, it slows the growth of the vertebral column as indicated by the shorter vertebrae of the proximal tail region. This is observable 13 days after fertilization. Second, it produces an embryonic anemia which is already in existence at 14 days after fertilization. It is postulated that the flexures are due to the retardation of growth at a time which is critical for the intervertebral disks. Whether this retardation is the primary effect of the gene and produces the anemia, or whether the anemia is primary and produces the retardation, the data do not show.
Evolution of the upper jaw mechanism in teleost fishes
Authors: Eaton Theodore H.
Published: February 2005

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.
Some critical points in the metamorphosis of the halichondrine sponge larva
Authors: Wilson H. V.
Published: February 2005

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.
The phenomena of anuran metamorphosis. III. The development of the thyroid gland
Authors: Etkin William
Published: February 2005

This paper presents a study of the growth and histological development of the thyroid in three species of frogs, the small Pseudacris triseriata, the large Rana catesbeiana and the intermediate Rana palustris. It was found that the history of the gland in relation to metamorphosis is essentially the same in all. Previous to metamorphosis the gland is small, and the cells very poor in cytoplasm. At the beginning of metamorphosis (i.e., rapid hind leg growth) the thyroid shows a marked acceleration of growth and activity, which continues and reaches a peak at the time of the emergence of the front legs. Late in metamorphosis a regression occurs.

The conclusion is drawn that there is a rising concentration of thyroid hormone during the course of metamorphosis. The author has previously shown that such a rising concentration will induce the normal pattern as to sequence and time spacing of metamorphic events.

The beginning of metamorphosis is conceived as dependent upon the time of stimulation of the thyroid and the pattern of its subsequent continuance as dependent upon the pattern of response of this gland.
The interkinetic migration of embryonic epithelial nuclei
Authors: Sauer F. C.
Published: February 2005

Nuclei of columnar epithelia of vertebrate embryos move to the free epithelial surface before a division, the movement of the nucleus accompanying a shortening of the columnar cell. After division at the free surface the daughter cells elongate, the nuclei passing away from the free surface. This is illustrated by drawings and measurements of cells of the fore‐gut it of the garter snake embryo. The elongation of these cells after mitosis is associated with an elongation of the spindle fibers to produce a prominent cytoplasmic fiber which persists through the interkinetic stage and into the next mitosis. The appearance of nests of nuclei in mitosis is accounted for by the fact that descendants of an earlier cell have kept approximately in step in their divisions.
The gularis muscle in Urodela
Authors: Eaton Theodore H.
Published: February 2005

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.
The adrenal‐autonomic complex in Alligator mississippiensis
Authors: Lawton Florence Emily
Published: February 2005

The adrenal‐autonomic systems were studied in embryonic and juvenile alligators. In the class Reptilia virtually no previous work has been done on the adrenal‐autonomic systems.

The adrenals are definite bodies, distinct from the kidney. In young forms they are in close proximity to the gonads and in both the embryonic and young forms the adrenals lie against the wall of the inferior vena cava.

Cortical cells predominate. In embryonic forms the medullary tissue is not dispersed as in older forms. The medullary tissue lies in close proximity to the blood sinuses or may completely surround them.

The arterial supply is scanty there being only a few small arteries to the adrenal while the blood supply from the inferior vena cava is profuse.

The innervation is segmental in nature with four or five consecutive sympathetic ganglia giving off sympathetic nerves to the adrenal. Parasympathetic innervation was not observed in the forms studied. The innervation suggests a transition from lower forms with their segmental diffuse medullary material to the higher forms that display concentration of nerve supply and adrenal tissue.
The relation of germ cell degeneration to modifications of the testicular structure of Plethodontid salamanders
Authors: Burger J. Wendell
Published: February 2005

A study of the male sexual cycles of five species of Plethodontid salamanders indicated that annually occurring non‐functional regions at the anterior and posterior ends of the testis are associated with the two types of germ cell degeneration: (1) extensive degeneration of secondary spermatogonia in the anterior region; (2) complete degeneration in the posterior region, beginning with the young spermatocytes, of all germ cells except the primary spermatogonia. The improbability of the posterior degenerations being caused by a suggested climatic action is discussed. The presence only in urodeles of a caudo‐cephalic polarity of spermatogenesis over the length of the testis and of these degenerations seem more than a coincidence. The abortive spermatogenetic cycle of immature males shows a caudo‐cephalic sequence and the stages of degeneration that are identical with the adult. Inanition experiments indicate that the formation of secondary spermatogonia and the ability to form sperm are not synonomous. It is suggested, therefore, that normally more of the testis is activated than can be brought to a successful spermatogenesis. Since spermatogenesis moves caudo‐cephalically, the posterior end will be left outside the functional zone, and consequently the cells degenerate. The anterior degenerations and the failure of anterior end of the testis to be involved in spermatogenesis, mark the anterior regulation of the spermatogenetic process. Degenerations can be regarded as the by‐product of the regulation of overactivation.