bluuebunny/crossref_metadata_2025_split huggingface dataset:
A mechanism for the coordination and regulation of ciliary movement as revealed by microdissection and cytological studies of ciliated cells of mollusks
Authors: Grave Caswell , Schmitt Francis O. 
Published: February 2005

AbstractSystems of fiber‐like structures traverse ciliated cells and epithelia in a way to suggest conduction paths for stimuli for coordinating and regulating ciliary movement, and results of microdissection support such an interpretation.Some fibers of the systems in epithelia of the gill terminate on the nuclear membrane, some between nuclei in the basal cytoplasm.The observed double refringency of the fibrillar apparatus places it in the category of irritable and contractile substance.Bipolar cells and nerve‐like fibers lie immediately below and parallel with ciliated epithelia of the gill, but direct connections of these fibers with the intracellular system, although suspected, was not demonstrated.Ciliated epithelia of the gill are syncytial in character in the direction of the beat of cilia.Interciliary structures occur in the cuticular portion of ciliated epithelia which are interpreted to function in taking up strains in the gelled cytoplasm caused by the beat of cilia.Cilia occur in pairs in epithelia of the gill, and members of pairs are fused at their distal ends.Each cilium, as seen in dark‐field illumination, pierces its basal body, and the fiber that is a continuation of the cilium divides immediately below the basal body into two; one diverging to the right, one to the left.Each cilium is composed of many delicate fibrillae.
The influence of temperature on the rate of locomotion in Amoeba II. The rate of locomotion in Amoeba at different temperatures
Authors: Schwitalla Alphonse M. 
Published: February 2005

AbstractIn general, the changes of locomotor rate of Amoeba under the influence of temperature are similar to the effects of temperature in other biological processes.The rate increases with rising and decreases with falling temperatures within a certain temperature range, this being, for the forms investigated, the interval between 6° and 23.5°C. In some individuals, however, these limits were found to be wider, extending from 2° to 26°. There is an average optimum at about 23.5°, beyond which an increase in temperature is followed by a decrease in rate. The immediate response of Amoeba to a change of temperature is variable, due, as was shown in a previous paper, to the fact that locomotor‐rate changes are rhythmic. The effect of a change of temperature is thus conditioned not only by the enviornmental factors, but also by the phases of the locomotor rhythm. This fact also makes it difficult to establish the exact quantitative relationship which exists between a change of temperature and the locomotor rate—an aspect which will be developed in a future paper.
Photoreceptors of Lumbricus terrestris, with special reference to their distribution, structure, and function
Authors: Hess Walter N. 
Published: February 2005

AbstractA special type of cell, called ‘Lichtzellen’ by Hesse, was found in the photosensitive regions of the earthworm. Wherever the epidermis is most sensitive to light these cells are most abundant. They are found in the epidermis of all segments of the body and also in nerve enlargements of the prostomium and the caudal segment, but the intersegmental and ventral regions of the different segments, except the more distal ones, contain none of them. They are supplied by nerves and each contains a characteristic inner structure, the optic organelle, composed of a large central hyaline structure, the lens, which is surrounded by a dense network of nerve fibrillae, the retinella. In hanging drops the lens was found to focus light in the region of the retinella irrespective of the direction of the rays.These cells are similar in structure and function to the visual cells in leeches. Available data indicate that these cells function as photoreceptors and that the fibrillae of the retinella are the direct receptors of light stimuli.Pigment is not associated with the photoreceptors in a way that suggests direct functional relationship, but there is a subepidermal pigment layer through which pinhole windows admit light along the path of nerves to each of the nerve enlargements containing photoreceptor cells. These windows open in such directions as to determine the direction of withdrawal of the worm.
The multiple testis in diemyctylus
Authors: Humphrey R. R. 
Published: February 2005

AbstractA study of the development and seasonal changes of the testis in Diemyctylus viridescens shows that accessory testicular lobes arise as follows: Emptying of the caudal zone of the testis at mating is followed by degeneration of the lobules (tubules) of that region, reducing it to a slender cord consisting chiefly of duct system and residual spermatogonia. A regeneration of lobules at the distal end of this cord later gives rise to the second or accessory lobe.Accessory lobes develop in immature males after a similar reduction of the caudal end of the testis through spermatogonial degeneration or an abortive spermatogenesis. The caudal germ‐cell cord thus formed is comparable to that resulting from extrusion of spermatozoa, and the development of new lobules at the distal end of this cord gives rise to a second lobe as in adult males. There is no evidence of the formation of a multiple testis by outgrowths from the primary lobe or by the junction of several lobes originally separate.A multiple testis occurs in Urodele species exhibiting two peculiarities of the spermatogenetic pattern: (1) a slow spermatogenetic wave and, (2) delayed regeneration of lobules emptied at mating or by degeneration of their germ cells. The number of lobes is correlated with the age of the individual. In Diemyctylus under 6 cm. the first accessory lobe has not yet developed.
The embryology of cryptobranchus allegheniensis. III. Formation of the blastula
Authors: Smith Bertram G. 
Published: February 2005

AbstractIn the blastula the region of accelerated cell division is on the ventral side of the egg, nearly opposite the site of the future beginning blastopore. The ventral wall of the blastocoele is thicker than the dorsal. In the very early gastrula a new region of accelerated cell division appears in the vicinity of the dorsal lip of the blastopore.A downward movement of material comprising the marginal zone of micromeres and the portion of the wall of the blastocoele immediately above it occurs during all the later blastula stages and continues until this material is carried below the level of the equator and involved in the process of gastrulation. On the dorsal side of the egg, this movement is more rapid than on the ventral side.In the late blastula stage there are evidences of growth in the region of smaller micromeres. In the very late blastula, a vertical groove appears at the dorsal margin of the floor of the blastocoele; this groove is believed to indicate the operation of factors concerned with gastrulation.In connection with the first nuclear division, evidences of cytoplasmic activity leading to the formation of the first cleavage furrow are described. As the blastomeres become smaller, progressive changes take place in the distribution of their cytoplasm.
Reversal of ciliary action in paramecium caudatum
Authors: Mast S. O. , Nadler J. Ernest 
Published: February 2005

AbstractMonovalent cation salts induce reversal in the direction of the stroke of the cilia; bivalent and trivalent cation salts with a few exceptions do not. Some acids induce reversal, others do not.The duration of reversed action varies with the kind of salt and with the concentration. As the concentration increases, the duration of reversed action increases to a maximum and then decreases to zero.Bivalent and trivalent cation salts neutralize the effect of monovalent cation salts. The relative amount required varies with the kind of salt used and with the concentration.The amount of a given salt required to neutralize another salt is not proportional to the concentration of the salt neutralized. Weber's law does not hold.The results seem to indicate that ciliary reversal is associated with differential adsorption and consequent changes in electric potential, but that there are also other factors involved.
Caste formation in the termite genus termopsis
Authors: Heath Harold 
Published: February 2005

AbstractIn Termopsis nevadensis only soldiers are produced during the first three or four years. When a normal colony comprises approximately twenty inhabitants, the first adult soldier is probably in the fifth instar; the second, somewhat larger, certainly is in the sixth. Later, others are produced in the seventh, and after the reproductive caste becomes differentiated, with about 450 inhabitants, they are in the eighth. Finally, in very old communities, some, at least, are in the ninth. The winged insect invariably is in the eighth.No sign of wings exists until the reproductive caste appears, after which every member of the sixth, and probably the fifth, instar possesses small, yet distinct, wing rudiments. These persist and enlarge in the later stages of the reproductive caste, and, of smaller size, they frequently occur in the soldier nymph and to a less degree in the adult. The third‐form adult is probably a sexually mature soldier nymph; the second‐form adult seemingly has the same origin and, though possessing wing buds, it does not belong to a special caste.Measurements of scores of recently hatched young disclose no differences other than those of ordinary variation, either in width of head, number of antennal segments, or size of brain and gonad. The first visible signs of caste differentiation appear at a relatively late stage. All of the instars are described in detail and the later ones are compared.
Oxygen consumption of individual pupae during metamorphosis
Authors: Taylor Ivon R. 
Published: February 2005

AbstractThe rates of oxygen consumption of single pupae of blowflies (Phormia terraenovae, Phormia regina, Lucilia sericata), of the flesh fly (Sarcophaga sarracenioides Aldrich), of the Mediterranean flour moth (Ephestia kuehniella), and of the bee moth (Galleria mellonella) during metamorphosis, until emergence, have been determined. The record for each pupa, with the exception of those of blowflies, is practically continuous day and night during the period of pupal development which lasted from 140 to 300 hours, according to the species, at the temperatures used. During pupal development there is first a period of decrease in rate, which is later followed by a steady increase until a short time before emergence, when a sudden decrease occurs.The ‘oxygen curves’ of the blowfly pupae (Diptera) are quite different from those of the flour‐moth and bee‐moth pupae (Lepidoptera), although all are of the same general U‐shaped type. There are strong indications of a specific difference in the curves of the blow‐fly pupae. The flour‐moth pupae curves differ slightly from those of the bee‐moth pupae. During the major part of development the rates of O2 consumption of pupae of both sexes of bee moth and flour moth are about the same, but near the end of metamorphosis the females have higher rates than the males. No such sex difference appears among the dipterous pupae used.
Studies on the Balantidium from the guinea‐pig
Authors: Scott Miriam Jackson 
Published: February 2005

AbstractObservations indicate that this Balantidium from the guinea‐pig is Balantidium coli, the form found in the pig and man. The lengths and breadths of this Balantidium and the ratios of length to breadth are very close to the measurements and ratios given by McDonald for B. coli. When plotted, the body lengths of the guinea‐pig parasites appear in two groups, the smaller individuals being the exconjugants. Many of these exconjugants resemble Neiva's B. caviae. The structure of the Balantidium from the guinea‐pig is essentially identical with that of B. coli as given by McDonald.Fission and conjugation of this ciliate follow the general course found in a number of other ciliates. During fission the micronucleus divides and the daughter micronuclei migrate to each end of the macronucleus before the latter divides. In conjugation there are two divisions of the micronucleus, one of these nuclei dividing to form the pronuclei. Pronuclear exchange and fusion are followed by a heteropolar division of the synkaryon, resulting in the formation of the new macronuclear and micronuclear anlagen.The parasite was found in the intestinal tissue of the host. No reproductive stages were found in the cysts. New hosts are invaded through contamination of the food and drink with the cysts.
The metabolism of amino‐acids by Paramecium caudatum
Authors: Emery Frederick E. 
Published: February 2005

AbstractThe object of the present study is to determine by quantitative means the rate at which a given number of paramecia can utilize the various amino‐acids and to study factors influencing this rate.The method consisted in testing the rate of utilization of isolated and mixtures of amino‐acids by a known number of Paramecium caudatum. The amino‐acids were used in 0.1 per cent solution and were tested, by the Henriques‐Sörensen formol titration method for amino‐acids, at the beginning and after the paramecia had lived in these amino‐acids for twelve hours. The difference between these two tests, figured in percentage, is considered as the amount utilized by the paramecia. The part played by bacteria was found to be negligible when isolated amino‐acids were studied. The influence of temperature on the rate of utilization of the amino‐acids has been studied, and the results show a direct relationship between the two.The rate of utilization was decreased by anaesthetics and nitroglycerin. A careful study has been made of a number of isolated amino‐acids and the rate of utilization of each discussed in relationship to the others studied. An explanation of why one amino‐acid was used more than another amino‐acid was sought for, but not found. A detailed discussion of the above points has been presented in the body of the paper.
The breeding season of the opossum (Didelphis virginiana) and the rate of intrauterine and postnatal development
Authors: Hartman Carl G. 
Published: February 2005

AbstractThe breeding season of the opossum at Austin, Texas, begins in January, following a three months' anoestrous period. The modal point for ovulation days is reached in the third week. The rate of intra‐uterine development was investigated chiefly by surgical removal of one uterus, noting the stage attained by the ova therein and allowing the surviving uterus to incubate its ova a precalculated period of time. Unique charts epitomize the results. The primitive‐streak stage is completed, the medullary groove and chorda begin at seven and one‐half days post coitum, seven days post ovulationem, leaving only five and one‐half days' actual development of the embryo to birth. The rate of development is compared with Eutherian mammals.The curve of postnatal growth has the shape of embryonic growth curve of higher mammals. The eyes and lips open, at about fifty days (young the size of mice). At this time the young leave the teat for the first time, but are not weaned for about thirty days more. Soon after weaning, the mother may become pregnant again. At ninety to one hundred days (young size of large rats), the young may begin to shift for themselves.
The history of the germ cells in the domestic fowl
Authors: Goldsmith Joseph B. 
Published: February 2005

AbstractMaterial of the domestic fowl of appropriate ages, ranging from twelve hours' incubation to the adult bird, was prepared for the purpose of studying the production and development of the germ cells.The primordial germ cells arise in the extra‐embryonic region anterior to the head fold in the region of the zone of junction during the primitive‐streak stage. These germ cells migrate, through the blood stream, to the region of the future gonad, where they develop into the definitive germ plasm.There is no widespread degeneration of the primordial germ cells after their arrival in the gonadal region, nor is there any widespread transformation of somatic cells into definitive germ cells.
Binary fission and endomixis in the Trichodina from tadpoles (Protozoa, Ciliata)
Authors: Diller William F. 
Published: February 2005

AbstractThis peritrichous ciliate lives as an ectocommensal on the skin and gills of anuran tadpoles. Its relation to described species of Trichodina is doubtful. This study was made almost exclusively on fixed and stained material. Binary fission is similar to that in other ciliates. The horseshoe‐shaped macronucleus condenses, then divides amitotically. The single small micronucleus forms a spindle containing between four and six chromosomes.Endomixis is of high incidence in the free‐living Trichodinae. Encystment was not observed. At the onset of endomixis, the macronucleus disintegrates into fragments which persist throughout the process. The micronucleus undergoes three rapidly succeeding mitotic divisions to form eight nuclei. There is no evidence of chromosome reduction during these divisions. Seven of the nuclei differentiate into macronuclear anlagen; the eighth becomes the functional micronucleus. Successive cell divisions—before each of which the micronucleus divides—distribute macronuclei to daughter cells. Variations from the regular process of endomixis may arise, 1) by precocious division of endomictic parents; 2) by extra divisions of the micronucleus; 3) by less than the usual number (three) of divisions of the micronucleus; 4) by hypertrophy and early differentiation of the micronucleus into macronuclei; 5) by unusual segregation of nuclei to daughters, and, 6) from miscellaneous causes.The significance of these variations is discussed in connection with the possible origin of bimicronucleate and amicronucleate races.
The chromosome cycle in the rotifer asplanchna amphora
Authors: Whitney David D. 
Published: February 2005

AbstractThe diploid number of twenty‐six chromosomes was found in the mature parthenogenetic female‐producing eggs and also in the somatic cells of the female embryos developing from such eggs. In the maturation stages of a few of these eggs the chromosomes were markedly larger than in the corresponding stages of the majority of the eggs. Whether this size difference of the chromosomes is correlated with male‐ and female‐producing individuals has not been determined. The mature parthenogenetic male‐producing eggs contain the haploid number of thirteen chromosomes, and this number was found also in the somatic cells of the young male embryos. The mature sexual eggs contain thirteen chromosomes.In spermatogenesis the secondary spermatocyte divisions are usually omitted and the secondary spermatocytes develop directly into the motile spermatozoa containing thirteen chromosomes. A few, however, of the secondary spermatocytes divide, forming spermatids containing fewer than thirteen chromosomes. These cells develop into the non‐motile and rudimentary spermatozoa.The motile spermatozoa containing thirteen chromosomes unite with the parthenogenetic male‐producing eggs containing thirteen chromosomes, thus producing the fertilized eggs with the diploid number of twenty‐six chromosomes. These fertilized eggs develop into female‐producing females which reproduce parthenogenetically.
Sex dimorphism in the syrinx of the fowl
Authors: Appel Fred W. 
Published: February 2005

AbstractThis study concerns the voice box or syrinx of the fowl in its possible relation to sex. Although neither hens nor capons crow, ovariotomized hens have been known to do so. It appears that a slight sexual dimporphism exists in the syrinx of certain fowls, and it was thought that a particular form might be essential to the act of crowing. However, no sexual dimorphism is apparent in the syrinx of the Brown Leghorn fowl.The syringeal structures of crowing birds (cocks and ovariotomized females) contain no features which cannot be demonstrated in normal females. Variations were found in the syrinx in this breed and in other breeds, but they had nothing to do with sex. There is a gradual ossification with increasing age and size. It may be concluded that there is no apparent reason why the female fowl should not crow, provided it had the instinct to do so properly developed. The sex hormones, if they act in voice production, must act entirely through the conditioning of the central nervous system.
Studies of parajulid diplopods. I. The development of the external sexual structures of Parajulus impressus say(8)
Authors: Hefner R. A. 
Published: February 2005

AbstractA description of the gross embryology of the sex apparatus of a common diplopod, the corn millipede. The life‐cycle of this animal involves eleven instars extending over a period of three years.In the male the true first legs are shed at the ninth ecdysis and the large clasping appendages are substituted through the last three instars. In the region of the second body somite the fused coxal plate and the penes are developed at the final molt; the second appendages are reduced at this time. The greatest changes occur in the region of the seventh somite, where the legs are shed about the eighth ecdysis and the gonopods developed through the remaining instars. It is evident that these gonopods arise as a modification of the sternites of the seventh somite.In the female the second legs are reduced to vestiges at the final molt. The structures at the mouth of the oviducts are developed from the surrounding tissues and the modified sternites of the reduced second legs. These changes are in progress as early as the seventh instar, but the greatest changes occur at the final ecdysis.
On the arterial system of the lizard Uromastix hardwickii
Authors: Bhatia M. L. 
Published: February 2005

AbstractThe arterial system of Uromastix hardwickii retains many primitive features and shows great resemblance and relationship to that of Sphenodon. The heart is typically reptilian. Two systemics and a pulmonary arch arise from the ventricle. The conus arteriosus is absent. The carotids arise together from the right systemic by means of a small common carotis primaria. A very well‐developed ductus caroticus connects each carotid with the systemic arch of its side. The ductus arteriosus (ductus Botalli) is absent.The dorsal aorta is formed by the union of both the systemic arches. The left systemic joins entire while the right one, which is termed systemicocarotid trunk, gives off the carotids, the vertebral, a single subclavian, and two pairs of parietal arteries, before the union. Anterior epigastric arteries are altogether absent. The dorsal aorta gives off fifteen pairs of parietal arteries which are segmentally arranged. All the main branches supplying the alimentary canal and other viscerala organs arise independently of one another, there being no such combination as is found in Varanus.