bluuebunny/crossref_metadata_2025_split huggingface dataset:
The development of the trunk and tail lymphatics and posterior lymph hearts in anuran embryos
Authors: Kampmeier Otto F. 
Published: February 2005

AbstractThis paper represents the third part of a monograph on the development of the lymphatics and lymph hearts of Anura. In this part are considered the origin and development of the subvertebral, lateral, and dorsal lymphatics of the trunk, the caudal lymphatics, and the posterior lymph hearts.The chief lymphatic trunks arise along the veins from a series of small, spindle‐shaped, and discontinuous anlagen which subsequently coalesce and thus establish continuity with one another. Lymph plexuses are formed from which emerge the main secondary lymph channels. After such trunks are laid down as indicated, smaller branches and capillaries spring from them by sprouting or extension, due to their actively proliferating endothelium.The posterior lymph hearts ‘crystallize,’ so to speak, from localized areas of the lateral lymphatic plexus. During its reorganization and differentiation, it temporarily separates from the surrounding lymph plexus. Other genetic details, such as the formation of its valves, histogenesis of its walls, number of hearts laid down, etc., are also considered. Twenty‐two figures (microphotographs and reconstructions) accompany the text.
Studies on the physiology of the liver VI. The effect of total removal of the liver in lower vertebrates
Authors: Magath Thomas B. , Mann Frank C. 
Published: February 2005

AbstractThe effect of removal of the liver has been noted in fishes, frogs, and turtles. As in the higher vertebrates, removal of the liver produced a fall in blood sugar and a loss in muscular tone. The lower vertebrates failed to respond to intravenous injections of glucose, as do the birds and mammals. They also fail to respond to maltose or levulose. The liver maintained the blood‐sugar level in the lower vertebrates, which is necessary for the maintenance of life.The mechanism of carbohydrate metabolism in the lower vertebrates may be different from that in the higher ones, in that glucose, when injected intravenously, apparently exercises a progressively less beneficial effect on the characteristic hypoglycemic condition which follows the removal of the liver of mammals and cold‐blooded vertebrates.
Natural partial fertilization in fasciolaria
Authors: Hyman O. W. 
Published: February 2005

AbstractOf the eggs laid by Fasciolaria about 1 per cent develop into veligers, about 2 per cent more undergo a few cleavage divisions, and about 97 per cent do not divide at all. The 99 per cent that fail to develop normally are ‘swallowed’ by the veligers. This study concerns itself chiefly with the ova that do not divide. Notes on normal development and on the ova that undergo atypical cleavage are included.All of the ova are found to be typical when passed from the ovary. To each ovum one to several sperms become attached at the vegetal pole in the region of a mass of undifferentiated protoplasm—the ‘polar mass.’ A fertilization cone forms in each ovum and a fertilization membrane. In typical development a yolk lobe is formed, the sperm enters in the usual way, and fertilization is completed as in many other mollusks. In 97 per cent of the ova the yolk lobe is not formed and the sperm does not enter. In these cases the wall of the egg nucleus remains intact a long time. The nucleus itself and the ‘polar mass’ sink into the egg and meet at the center. Then the nuclear wall disappears and an atypical diaster is formed. However, cleavage is not begun and the chromosomes form vesicles that remain near the center of the ovum until it is ‘swallowed’ and digested by the veliger.
Development of the pelvic fins of acipenser ruthenus. New data for the theory of the paired fins of fishes
Authors: Sewertzoff A. N. 
Published: February 2005

AbstractThe pelvic fins of the ancestors of the Chondrosteoidei possessed a metameric musculature and their skeleton consisted of a large number of metamerically arranged cartilaginous fin‐rays, to which were attached osseous lepidotrichia. Evolution has involved the concrescence of separate elements to form the basal cartilage, the proximal end of which forms the girdle of the fin; the loss of a number of the fin‐rays, and the atrophy of distal elements of the rays. The adult Chondrosteoidei have retained the primitive fin structure which characterized the elasmobranchs of the Palaeozoic period and which has disappeared in recent forms.
Molgula citrina (Alder and Hancock). Activities and structure of the free‐swimming larva
Authors: Grave Caswell 
Published: February 2005

AbstractThe activities of the larva and the responses and orientations it makes to external stimulation, and the structural organization by which these activities are produced, are described and figured.Existing systematic confusion of M. citrina with other species (M. manhattensis, M. nana, and M. microsiphonica) is cleared. The duration of the period of larval life is found to vary between 5 and 170 minutes. A proportionally small number retain the larval form a longer time. During larval life, periods of swimming movements alternate with periods of inactivity, the latter, at first of momentary duration, becoming longer and longer until activity ceases.No light receptor exists and no response to light is made. A statolith is found in the sensory vesicle, and frequent geonegative orientations are made during the free‐swimming period. These are of short duration and tend to occur, 1) when it emerges from the parent; 2) at the beginning of each of the frequently recurring periods of swimming activity; 3) immediately upon making contacts. Unoriented movements follow each orientation and constitute much the greater part of behavior.The larva lacks definite organs of attachment. The entire surface of the tunic becomes adhesive at the time of metamorphosis. Only those structures that make up the action systems of the larva are fully differentiated, all other parts are embryonic in condition.
The regulation of skin‐pattern in an amphibian, Diemyctylus
Authors: Collins H. H. , Adolph E. F. 
Published: February 2005

AbstractThe integument of the vermilion‐spotted newt contains three kinds of pigment‐–yellow, red, and black. The yellow is uniform and continuous over the whole body; the red and black are discrete, and are chiefly in large spots. The pattern does not change measurably in an adult individual.Functional changes in contraction of the scattered dorsal melanophores were uncommon. The only efficient single factors found were a long subjection to low temperature (expansion) and injection of pituitrin (contraction).Removal of skin was followed by a rapid mass migration of dermal elements into the wound area. Melanophores were thus furnished to a dorsal wound, and after several months black spots formed from these. Red pigment never regenerated nor migrated into a wound. Yellow pigment was formed in situ after the wound had completely healed.Auto‐, homo‐, and heterotransplants lost their pigment patterns and were gradually reorganized so as to conform in gross appearance to the surrounding pattern of the individual host's skin. The transformation was never complete in eight months, but new black spots and new yellow pigment eventually formed.The behavior of melanophores during morphogenesis differed for specific areas of the integument. Their movements and aggregation were highly coordinated among themselves.
Cell division and ciliogenesis in the ciliated epithelium of the pharynx and esophagus of the tadpole of the green frog, Rana clamitans
Authors: Kindred James E. 
Published: February 2005

AbstractAll phases of mitosis have been observed in the ciliated cells of the pharynx and esophagus of the tadpole of the green frog, Rana clamitans. Centrosomes have been observed in ciliated cells. These data contravene the hypothesis of Lenhossék and Henneguy to the effect that ciliated cells cannot divide by mitosis because they have lost their centrosomes in the formation of the basal corpuscles to which the cilia are connected, and the corollary to this hypothesis (Jordan, '13), that in consequence ciliated cells must divide by amitosis. From counts of cells with cilia, those without cilia but with basal corpuscles, and those without either cilia or basal corpuscles in different phases of mitosis, it is inferred that the cilia are lost during mitosis.Cilia sprout from basal corpuscles, and not from mitochondria in cells undergoing ciliogenesis. From the presence of diplosomes in the distal region of cells in which basal corpuscles are developing, it is assumed that the basal corpuscles arise by partition of the centrosome of the preciliated cell. The centrosome, however, does not become completely lost by reason of this process, but retains enough vitality to insure mitosis. Amitosis, which occurs in some of the ciliated cells, results, according to these data, from degree of differentiation, not from structural deficiency.
Some cytoplasmic structures in the male germ cells of gelastocoris oculatus (Toad bug)
Authors: Payne Fernandus 
Published: February 2005

AbstractThe chondriosomes are first recognizable as two clusters in contact with the nuclear wall. Beneath each cluster lies a chromosome. This relationship is constant and indicates that these two chromosomes play a part in the growth and development of the chondriosomes. The two masses fuse and the single mass grows considerably during the early growth period. Later it breaks up into a number of threads which become rings in the late growth period. The rings fuse into the large nebenkern which plays the usual rôle in the formation of the tail.The Golgi material is first seen outside of the chondriosomal cap. Early in the growth period, it breaks up into Golgi bodies which remain distributed in the cytoplasm during the growth period and spermatocyte divisions. About the midgrowth period a large number of spheres suddenly arise. Since they later fuse to form the idiosome, they are called the proidiosomal spheres. These spheres, which may originate in the Golgi bodies, remain scattered in the cytoplasm during the growth period and spermatocyte divisions. In the spermatid the Golgi bodies collect about the idiosome to form the acroblast. The Golgi remnants pass into the cytoplasm of the tail, while the acrosome elongates into a tail‐like structure at the anterior end.The centriole was followed with unbroken continuity from the midgrowth period into the middle‐piece of the sperm.
The chromosomes of clypeaster rosaceus
Authors: Gardiner Mary S. 
Published: February 2005

AbstractThe diploid number of chromosomes obtained from counts of anaphases of the first somatic mitosis is found to be forty‐four. Of these, seven have terminal, thirty‐seven non‐terminal attachment, giving a distribution of seven rods, thirteen V's, and twenty‐four J's. The number is constant in all the fertilized eggs counted, indicating an XX–XY arrangement of the sex chromosomes.
The significance of hemal nodes
Authors: Jordan H. E. 
Published: February 2005

AbstractThe investigation is based upon hemal nodes of dog, man, and sheep. The material can be arranged in a regressive series leading from a typical lymph node, except for the occurrence of blood in parenchyma and sinuses, to a lymphoid structure at a late stage of involution. These structures uniformly lack lymphatics. There is no evidence of direct luminal connection between the blood‐vascular supply and the sinuses. The observation that certain cervical and subcutaneous lymph nodes of the rabbit undergo a myeloid metaplasia following atrophy and disjunction of their lymphatics is used as an explanatory key of hemal nodes. According to our view, hemal nodes represent stages in the involution of transient lymph nodes. Disjunction of the lymphatics leaves the sinuses filled with entrapped lymphocytes. These differentiate into erythrocytes. These red blood cells may disintegrate and pass into solution or be removed either by giant cells or mononuclear phagocytes. Late stages in this process are represented by small irregular masses of lymphocytes, with wide sinuses practically free of blood.
Parental chromosome dimensions in Ascaris. A study of the effect of cellular environment on chromosome size
Authors: Hance Robert T. 
Published: February 2005

AbstractIn the early cleavage stages of Ascaris the homologous chromosomes are of unequal length. Measurements show that these homologues fall into two sharply defined groups suggesting their biparental origin. The shorter are considered to have come from the male.As the age of the embryo increases, these differences between the chromosome mates tend to become less, and it is suggested that at some later period in the history of the animal this difference will entirely disappear in response to the effect of continued existence in a common environment. The length of the chromosomes is very slightly shortened during the early cleavage divisions, while the area of the equatorial cross‐section of the cells becomes enormously reduced.
The exoskeleton as a factor in limiting and directing the evolution of insects
Authors: Kennedy Clarence Hamilton 
Published: February 2005

AbstractEach step forward in the evolution of new organs or new abilities has made possible further evolution, but at the same time has set up mechanical and physiological conditions that place definite limits on the future possibilities of evolution. The exoskeleton has made possible very definite advances in the evolution of insects, but at the same time has limited their evolution in fully as many other ways.Opportunities in evolution opened up by an exoskeleton are its use as armor, as a skeleton, in the development of wings, as protection against desiccation. It has conditioned small size opening up numerous limited environments, increasing mutability due to short life. It conditions a tracheal system which speeds metabolism, and a variety of specialized mouth parts as well as locating the sense of smell on the surface where it is more effective. Metamorphosis evolved from ecdysis.Limitations imposed by an exoskeleton are small size, simple nervous system due to small size, short life preventing education, inflexible societies due to simple nervous system, cold‐bloodedness, clumsy appendages, loss of closed blood system, excretory system reduced to malpighian tubules, poor development of touch and hearing and mosaic vision.
A neuromotor apparatus in the ciliate Dileptus gigas
Authors: Visscher J. P. 
Published: February 2005

AbstractA system of fibers has been found in Dileptus gigas which is probably a neuromotor apparatus. A distinct elongated basal rod, found near the base of the gullet, gives rise to three sets of fibers: (1) a set of heavy fibers radiates out around the funnel‐shaped gullet; (2) a pair of heavy fibers pass directly from the basal rod to the band of trichocysts, one on each side, extending to the tip of the proboscis; (3) a set of very delicate branching fibers is distributed over the surface of the organism.This system of fibers is held to be a neuromotor apparatus, because, (1) the general structure and appearance of the fibers suggest a neuromotor function and, (2) there is little or no evidence indicating any other function; and because, (3) the fibers in this system are connected to the most highly specialized structures in Dileptus, and, finally, because, (4) they are similar to structures found in other forms for which a neuromotor function has been experimentally demonstrated.
Conjugation in the ciliated protozoon, Dileptus gigas, with special reference to the nuclear phenomena
Authors: Visscher J. Paul 
Published: February 2005

AbstractIn conjugation fusion occurs along the entire oral surfaces of the proboscides of Dileptus gigas. Two size‐reducing divisions occur in rapid succession immediately preceding conjugation. Only one of the many micronuclei takes part in the process of nuclear reorganization. All other chromatic material is massed at this time in the posterior portions of the conjugants. The pronuclei are derived from the single active micronucleus, and interchange occurs immediately preceding the separation of the mating individuals. The fertilization nucleus divides to form two nuclei of diverse size. The smaller one produces thirty‐two or sixty‐four micronuclei, while the larger one divides to produce a like number of macronuclei, each of which finally breaks up into many chromatic granules which form the numerous densely staining nuclear derivatives which are characteristic of the vegetative stage of Dileptus gigas.In the early stages of this reorganization process specimens are frequently found with from two to eight distinct nuclei often arranged in a series as in a beaded nucleus. This condition probably explains the frequent references in literature regarding such a nuclear condition in Dileptus.Dileptus gigas has, accordingly, in the vegetative stage, a multinucleate condition with reference to the micronucleus and a fragmented or distributed condition with reference to the macronucleus.
Developmental modification and elimination of the larval stage in the ascidian, Corella willmeriana
Authors: Child C. M. 
Published: February 2005

AbstractThe eggs of Corella develop in the atrial chamber of the parent at a pH below that of normal sea‐water (pH 7.4 ±). When removed to normal sea‐water in early stages and under certain other experimental conditions, larval development is more or less inhibited, the tail being most inhibited, the dorsal region somewhat less. The free larval stage may be eliminated and later development and metamorphosis may proceed normally to an advanced stage in the chorion and give rise to normal ascidians. The region most inhibited are, in general, those which possess the highest reducing power, as indicated by KMnO4. Experiments made in the attempt to control development all agree in indicating that the early stages are adjusted to a certain CO2 concentration approximately that of the atrial chamber and presumably near that of the body. Solutions of the same pH may or may not inhibit development according to their CO2 content.The tail, the region of highest reducing power in the embryo during its development, is most inhibited; the dorsal region, the next most rapidly reducing region, is next in degree of inhibition. All differences in reducing power disappear when, or soon after, the animals are killed by other agents before treatment with KMnO4.
A comparative study of the chromosomes of the Norway rat (Rattus norvegicus ERXL.) and the black rat (Rattus rattus L.)
Authors: Pincus G. 
Published: February 2005

AbstractBy the use of a satisfactory technique, excellently preserved spermatogenetic tissue was had both for Rattus rattus and Rattus norvegicus. The careful examination of twelve spermatogonial cells of the former species and of twenty in the latter species shows that R. rattus has forty diploid chromosomes and R. norvegicus, forty‐two. A careful examination of the haploid cells of both species, both in the first and in the second spermatocyte divisions, confirms the diploid determinations.Both species have an unequal pair in the spermatogonial divisions and the finding of a similar unequal pair in the first spermatocyte division constitutes the evidence for an X‐Y mechanism in each. A comparison of the morphology of the first spermatocyte tetrads in the two species reveals the presence of a large K‐shaped chromosome in R. norvegicus which is not present in R. rattus. Furthermore, a comparison of the X‐Y complex in both the spermatogonial and first spermatocyte divisions shows that these are morphologically different in the two species, the Y in particular being markedly dissimilar in size. A short discussion as to the bearing of these findings on the questions of the origins of the two species and their known intersterility is presented. The marked similarity of the tetrads of the black rat to those described for the mouse is noted.
The digital pads of the tree frogs. A study of the phylogenesis of an adaptive structure
Authors: Noble G. K. , Jaeckle M. E. 
Published: February 2005

AbstractThe digital disks of the tree frogs are covered ventrally with a superficial layer of vertically elongated, fibrous, and distally free cells between which there empty a series of convoluted mucous glands. The latter are surrounded and, in the larger‐disked species, divided into blocks by sheets of collagenous fibers. The glands are emptied by the squeezing together of the collagenous fibers when the body weight exerts a pull on the terminal phalanges. The disks function by friction, cohesion, and adhesion.The digital‐disk apparatus was fully established before certain groups of frogs became arboreal. It is retained in others which have reverted to the terrestrial habit. The intercalary cartilage increases the efficiency of the apparatus. It did not arise in phylogeny until after the apparatus was developed.As the digital disks vary in extent in both arboreal and terrestrial species, arborealism seems to have resulted from a chance occurrence of large disks in the smaller‐bodied forms; at least, there is no progressive modification of the digits toward particular habitat requirements.The subarticular tubercles of many Salientia develop typical climbing apparatus. This may or may not be correlated with an arboreal habit. In the species with the largest subarticular tubercles no apparatus is present. Arboreal salamanders exhibit no special climbing mechanism, but adhere by pressing their moist integument against the substratum.
Spermatogenesis of Bruchus quadrimaculatus (Coleoptera: Bruchidae)
Authors: Brauer Alfred 
Published: February 2005

AbstractNotwithstanding the fact that several species of Bruchidae have been used by geneticists for several years, no cytological studies have as yet been made on any member of this family of the Coleoptera. The present paper gives a general account of the spermatogenesis of Bruchus quadrimaculatus Fabr.The spermatogonia undergo two mitotic divisions. After the second division, the nuclei remain small and very dense for some time before the beginning of the growth phase. During this interval the nuclei do not assume again the characteristics of the interkinesis stages. In the primary spermatocytes typical tetrads are formed. The chromosomes are asymmetrically V‐shaped. The end of one arm of the ‘V’ fuses with the end of the corresponding arm of its synaptic mate. Disjunction takes place in the primary spermatocyte division. After the division of the secondary spermatocytes, the chromosomes become vesicular and form a reticular nucleus in the spermatid, after which the chromatin becomes deposited as a chromatin rim around the nuclear periphery. The diploid number of chromosomes is nineteen in spermatogonia and in male somatic cells, and twenty in female somatic cells. An unpaired X chromosome is present in the spermatogonia, which fails to divide in the primary spermatocyte division, but passes as a whole to one pole in advance of the autosomes. The X chromosome divides normally in the secondary spermatocyte division with the autosomes.In the method of sex determination, Bruchus does not follow the method of the majority of beetles, since most of those studied adhere to the X‐Y type.