bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the role of acetylcholine in regulating the rate of the early chick embryo heart
Authors: Roberts Carmel Montgomery , Gimeno Martha A. , Leyden Webb J. 
Published: February 2005

AbstractA study has been made of the effect of acetylcholine upon the heart rate of the early chick embryo, and it has been noted that under certain experimental conditions acetylcholine stimulates the heart rate during the period of vagal innervation, while depressing the heart rate after the nerve supply is established. Isolated chick embryo hearts freely suspended in a phosphate‐buffered (bicarbonate‐free) medium beat at only about one‐third their in ovo rates, and acetylcholine produces biphasic effects of stimulation and inhibition of the heart rate depending upon the concentration of the drug and the age of the hearts, the maximal stimulation occurring at five days. When suspended in Krebs bicarbonate medium the hearts beat at rates of about 72 to 74% their in ovo rates, and acetylcholine produces only slowing of the heart rate. This effect of acetylcholine can be diminished or reversed when an inhibitor of endogenous acetylcholine, hemicholinium‐3 is added. We have postulated that both inhibitory and stimulatory receptors for acetylcholine exist in the early chick embryo heart and that the response to added acetylcholine depends in part on levels of endogenous acetylcholine already present in the heart. The role of endogenous acetylcholine in regulating heart rate is discussed.
The metabolism of homogenates of the mouse epididymis
Authors: Elliott Paul R. 
Published: February 2005

AbstractThis study has attempted an evaluation of the in vitro metabolic characteristics of the epididymis of the mouse and a definition of areas for further research pursuant to the elucidation of the role of this organ in the process of sperm maturation and storage.Optimal conditions were ascertained for the manometric measurement of total respiration and for the estimation of glycolytic activity by assay of lactate accumulation and phosphate esterification in fluoride poisoned homogenates. Homogenates of mouse kidney were utilized in all experiments for comparative purposes.The in vitro data presented indicate the epididymis to be predominantly oriented to a glycolytic metabolism. It is suggested that this metabolic orientation when considered with the results of other investigators is compatible with a hypothesis for the secretion of lactic acid by the epididymal epithelium into the lumen of the epididymal canal for spermatozoan utilization.
Permeability to water and sodium of the crocodilian, Caiman sclerops
Authors: Bentley P. J. , Schmidt‐Nielsen Knut 
Published: February 2005

AbstractIn freshwater the caiman gains water at the rate of 3.5 ml/kg hr or 1.1 μl/cm2 hr. Of this 70% is the result of uptake through the skin, the rest being due to drinking. This gain in water is excreted by the kidneys as a hypotonic urine. Urine sodium losses are reduced by active sodium uptake from the urine during storage for 3 to 4 hours in the cloaca. In vitro and in vivo experiments indicate that the skin is somewhat permeable to sodium, which moves along concentration gradients.In air the caiman loses water by evaporation (1.2 μl/cm2 hr). About 75% of this takes place from the skin.In 3.3% NaCl solution caimans show elevated serum sodium concentrations and 20% of them die within 24 hours. The sodium accumulation is mostly due to drinking (4.4% of the body weight/day), and only to a minor extent to osmotic water loss through the skin (2.5% of the body weight/day or 0.6 μl/cm2 hr). The permeability of the caiman is compared to that of fishes, Amphibia and other reptiles.
The effect of volume expansion on the electrophoretic mobility of cells
Authors: Patinkin D. , Doljanski F. 
Published: February 2005

AbstractDeterminations of electrophoretic mobility were made on Landschütz ascites carcinoma cells and mouse leucocytes suspended in a series of solutions of differing hypotonicity. The curves relating volume to the reciprocal of tonicity indicated that both types of cells conform fairly well to the Van't Hoff‐Mariotte Law from a relative tonicity of about two down to 0.325. Beyond this point, leucocyte volumes tended to taper off to a plateau whereas ascites cell volumes first showed an increase in slope and then leveled off. Reversal of hypotonically swollen cells to isotonicity brought about a shrinking of the cells back to their original volume. These expanded and contracted cells were shown to retain other of their normal properties such as impermeability to vital dyes and for ascites, the ability to proliferate upon transplantation. It was concluded from these observations, that throughout their extensive expansion in hypotonic media, the cells remained essentially viable and intact. The possible effects of increase in cell volume on surface area changes were discussed. There was no change in the electrophoretic mobility of the cells in the entire range of hypotonic solutions tested. Enlargement of cell volume without change in mobility may have been produced by an expansion or unfolding of the ultramicroscopic crenations of the membrane and a corresponding exposure of similar surface to the electrokinetic plane of shear.
A histochemical study of intracellular digestion in triclad flatworms
Authors: Willier B. H. , Hyman L. H. , Rifenburgh S. A. 
Published: February 2005

AbstractThe course of digestion of an essentially protein food (beef liver) was followed by histological and histochemical methods in Planaria dorotocephala. After an average fasting period of two weeks, the planarians were fed and examined at close time intervals, ranging from one minute to eighty‐seven days after feeding. Liver particles are engulfed by the phagocytic cells of the intestine into food vacuoles, where a series of digestive changes occur. The liver particles coalesce into a granular spherule which gradually condenses into a homogeneous and chromatophilic spherule. As the spherule transforms from a granular to a homogeneous condition, it exhibits a gradually increasing affinity for stains, an intensified protein reaction, and a gradual diminution in size. These spherules are protein, since they give positive xanthoproteic and Millon reactions.The homogeneous protein spherules gradually disappear, beginning at about twelve hours after feeding and continuing until the fifth day. During this period fat‐droplets form, gradually increasing at the expense of the protein spherules. The protein spherules apparently dissolve into the cytoplasm, furnishing intermediate chemical compounds (tests indicate that a carbohydrate stage does not intervene) from which fat is synthesized. It thus appears that the fat is formed from the protein spherules. The fat thus formed is stored in the phagocytic cells, and remains unchanged in quantity for a fasting period lasting six weeks, after which it gradually diminishes. During the engulfment of the food, the fat decreases markedly, apparently furnishing energy for phagocytic activities. A few of the protein spherules may persist as «protein reserve».
Correlations of the musculature and the movements of the skull in natrix, with some suggestions of homology in the lacertilians
Authors: Adams L. A. 
Published: February 2005

AbstractThe musculature of the ophidian head is a fairly complex structure, due to the specialization of the skull and the peculiar movements and motions made possible by the high degree of streptostylism.This musculature has been derived from the lacertilian type by a splitting and a shifting of the original elemental muscle masses of this group. Most of the muscles are clearly homologous with those of the Lacertilia. Some cannot be homologized by a study of the mature forms.The greatest differences lie in the separation of the muscle masses in the ophidia, as compared with the undivided masses in the Lacertilia. Since the jaw movements of the Lacertilia are rather simple, there is no need for any subdivision or splitting of the jaw muscles, but with the complex movements of the ophidia this becomes necessary.A few of the ophidian muscles appear to be neomorphs, as no key to their origin could be determined by a comparison with lacertilians.
The growth and chemical composition of three species of turtles fed on rations of pure foods
Authors: Pearse A. S. , Lepkovsky S. , Hintze Laura 
Published: February 2005

AbstractPainted turtles, gopher tortoises, and terrapins were fed on various mixtures of sand, salts, dextrin, casein, cod‐liver oil, wheat, eggs, lettuce, and meal worms. Each individual was weighted weekly for about a year and then killed for analysis, the water, ash, nitrogen, and fat being determined. Some individuals increased in weight as much as 75 per cent, others lost weight. Judged by growth and chemical analyses, the food requirements of chelonians, as representative poikilothermal vertebrates toward nutritive substances (including vitamines) are similar to those of homoiothermal animals.
Structure, movement, locomotion, and stimulation in amoeba
Authors: Mast S. O. 
Published: February 2005

AbstractAmoeba proteus contains a central elongated fluid portion (plasmasol), a rigid layer surrounding this (plasmagel), a thin elastic surface layer (plasmalemma), and a hyaline layer between the plasmagel and the plasmalemma which is fluid at the tip of active pseudopods and in certain other regions.The plasmasol is an emulsion. It consists of a fluid in which various vacuoles and granuoles are suspended. The plasmagel is probably alveolar in structure. It contains the same kinds of substances as the plasmasol, but some of the fluid appears to be gelated so as to form alveoli. The plasmalemma probably consists of interwoven protein fibers and a lipoid which fills the interstices.The plasmasol is probably hypertonic; the plasmagel and the plasmalemma are probably semipermeable. This and other factors result in an excess inflow of water, stretching the plasmagel and the plasmalemma. When a pseudopod is formed, the inner portion of the plasmagel liquefies locally. This produces a local decrease in elastic strength resulting in the formation of a protuberance, a pseudopod. As this is formed there is contraction at the posterior end, resulting in forward flow of the plasmasol and extension of the pseudopod.If the pseudopod is attached, the plasmalemma, being attached to the substratum and to the adjoining plasmagel, slides over the plasmagel above and remains stationary below, rolling movement results. If it is free, the plasmalemma is stretched out with movement in it equal on all sides. If the free pseudopods become attached to the substratum at the tip after they are thus formed, walking movement results.During locomotion of either type, the plasmasol continuously gelates at the tip of the extending pseudopods forming plasmagel, and the plasmagel continuously solates at the posterior end forming plasmasol.Response is due largely to changes in the elastic strength of the plasmagel in the adhesiveness of the plasmalemma and in turgidity.Locomotion in Amoeba verrucosa is in principle the same as it is in Amoeba proteus.
The cheek pouches of Richardson's groundsquirrel, citellus richardsonii, sabine
Authors: Sleggs George F. 
Published: February 2005

AbstractThe lips of the animal are modified in relation to the act of passing seeds into the sac. The cheek‐sacs are invaginations of the buccal mucosa, and their development as diverticula of the vestibulum oris is associated with the establishment of extrinsic muscles, derived from the platysma. The sac is invested by a coat of striated muscle. The epithelial lining of the sac attains a degree of complexity comparable to the epidermis of the skin, except that a stratum lucidum and stratum granulosum are not developed. No glands are developed in the mucous membrane of the sac.
Autotomy in Arachnida
Authors: Wood Florence Dowden 
Published: February 2005

AbstractOn the basis of experimental study and observations on the morphology of the legs of spiders, P. Friedrich described a cutting device within the trochanter which would sever that appendage from the body when the leg was stimulated by injury.A reinvestigation of the problem yielded entirely contrary results. Experiments calculated to induce spontaneous amputation through an automatic reflex in the leg were negative on scorpions, harvestmen, and more than a dozen species of spiders. A detailed morphological study of the skeleton and musculature of the arachnid leg showed that no autotomizing device exists, either in the skeleton or in the arrangement of muscles (as is usually supposed). In all species studied, except the scorpion, severance of the leg from the body occurs most readily at some given point. The point at which severance readily occurs is directly correlated with a definite structural weakness in the skeleton and musculature. The spider itself removes an injured leg by grasping the stump with its mouth‐parts. No such injured stump falls off spontaneously or without the application of tension. Scorpions do not autotomize appendages under any stimulation, nor do they show any anatomical weakness in the leg skeleton or musculature.Autotomy as an automatic reflex does not exist in the Arachnida.
The comparative morphology of the secondary sexual characters of elasmobranch fishes. The claspers, clasper siphons, and clasper glands. Memoir X
Authors: Leigh‐Sharpe W. Harold 
Published: February 2005

AbstractA summary is given of the previous memoirs, and an attempt has been made, upon the three characters of this investigation, to arrange the genera into families, which agree, with two exceptions (Mitsukurina and Dicerobatis), with preexisting families. Some deductions are drawn as to relationships and attention is drawn to Cestracion galeatus and Triakis as connecting links. Separate families are erected for Dicerobatis and Mitsukurina, and the latter is placed near to Notidanus. Resemblances are shown between Chlamydoselachus and the Holocephali. The Trygonidae, Torpedinidae, and Rhinobatidae are singularly uniform families. An index is added both general and specific.
The effects of mechanical shock on locomotion in Amoeba proteus
Authors: Folger Harry T. 
Published: February 2005

AbstractAmoeba responds to a mechanical shock by a cessation of movement which occurs shortly after the application of the stimulus. The length of the reaction time, the period intervening between application of stimulus and the response, varies inversely with the magnitude of the shock. After stopping Amoeba remains quiescent for a short time, and the length of this period of quiescence varies directly with the magnitude of the shock. A certain amount of time must elapse after a reaction before another can be obtained; during this time the animal reverts to the physiological state which existed prior to the first shock.Partial recovery from the effects of a shock is manifested by a reaction time that is longer than after complete recovery, and a period of quiescence which is shorter. A shock which in itself is too slight to cause a cessation of movement may result in the lack of a response to a heavier one which follows immediately after it, although under other conditions the second shock would have called forth a reaction. If the second shock, however, is made sufficiently heavy, it will bring about a response, despite the effects of the first. This is what would be expected if the reactions take place in accordance with the Weber‐Foechner law.
A new dorsal gland in the ground‐squirrel, Callospermophilus, with a note on its anal gland
Authors: Hatt Robert Torrens 
Published: February 2005

AbstractIn the golden‐mantled ground‐squirrel, Callospermophilus, a spatulate glandular area has been noted in the skin of the back. It has been found in the following species: C. l. lateralis, C. l. arizonensis, C. l. caryi, C. l. saturatus, C. l. tescorum, C. c. chrysodeirus, and C. bernardinus. Probably it is common to the genus.The individual glands making up this area are modified and enlarged sudoriparous glands. They are divided into a tightly coiled and branched fundus, a large sinus, and a duct which passes caudad and outward to its exit at the surface.The glands secrete a strongly smelling oil, which is probably left on vegetation and other objects in the animal's environment and serves as a source of information to other members of the species. The glands are more active in spring and summer than in winter. They are stimulated by excitement. While present in both sexes, both adult and juvenile, they are best developed in adult males.Callospermophilus has three anal glands. These have flat‐topped, straight‐sided nipples which are protruded from the anus if the animal is frightened. A milky substance with a very weak odor can be extruded.
The chromosomes of the house mouse
Authors: Cox Elizabeth K. 
Published: February 2005

AbstractThe spermatogenesis of the domestic mouse has been studied. There are forty chromosomes in spermatogonia and twenty in primary spermatocytes. The sex chromosomes are of the usual X‐Y type. Especial attention has been devoted to the study of chromosome morphology, both in spermatogonia and in primary spermatocytes.
Studies of hyperthyroidism IV. The behavior of the epidermal mitochondria and the pigment in frog tadpoles under conditions of thyroid‐accelerated metamorphosis and of regeneration following wound infliction
Authors: Speidel C. C. 
Published: February 2005

AbstractIn the epidermal cells of green‐frog tadpoles (Rana clamitans) there are present coarse, conspicuous mitochondrial threads. In the dorsal body regions, epidermal cells of the middle layers also contain pigment granules, grouped in crescentic masses in the distal portions of the cells.Administration of thyroid extract results in permanent disappearance of the mitochondrial threads and disappearance to a large extent of the epidermal pigment granules. Processes of cellular dedifferentiation and proliferation occur rapidly over widespread areas, the mitochondria undergoing intracellular resorption. A new type of epidermis is developed containing many cutaneous glands, adapted for the approaching terrestrial life.Wound infliction induces similar processes of cellular dedifferentiation and proliferation in the epidermis in the immediate vicinity of the wound. Cells in this region lose their mitochondrial threads by intracellular resorption, and there is also some disappearance of pigment granules. The new epidermal cells in the early stages of regeneration produce neither mitochondrial threads nor pigment. This condition is not permanent, however, and in the later stages the larval characteristics appear again, both mitochondrial threads and pigment being redifferentiated.In the hyperthyroid animals there is also a significant mobilization of mesenchymal chromatophores, correlated to some extent with the loss of epidermal pigment.The significance of epidermal changes is discussed with reference to cutaneous abnormalities associated with hyperthyroid and hypothyroid conditions.
The prenatal skull of the Canadian porcupine (Erethizon dorsatus)
Authors: Struthers P. H. 
Published: February 2005

AbstractThis study represents the first critical investigation on the development of the embryonic skull of the porcupine. A complete series of stages makes it possible to trace the developing chondrocranium from its first formation in precartilage to its later transformation into cartilage bone. Concurrent with this growth is the investment of the cartilaginous cranium by membrane bone.The very primitive nature of the chondrocranium offers an excellent opportunity to discuss the existing problems of the embryonic skull from a new angle. Evidence is presented in support of the assumption that the ala temporalis is the homologue of the cynodont epipterygoid. The lamina parietalis develops from a single chondrifying center, thus producing a different arrangement of parietal elements from that found in most mammals. New evidence as to the relationship of the dens epistrophei and basal plate is presented. The position of the internal carotid artery on entering the cranium is different from the condition found in most mammals and throws new light on the interpretation of surrounding structures. The presence of a structure comparable with the crista longitudinalis of Lacerta shows close affinity to the solum nasi of more primitive forms.The great specialization of the face is seen in the early and rapid growth of the membrane bones. The chondrocranium is long persistent and cartilage bone appears late in embryonic life.
The formation of contractile vacuoles in Amoeba proteus
Authors: Day Howard Calvin 
Published: February 2005

AbstractThe history of investigations on the contractile vacuole is reviewed briefly and brought up to date.The study of the contractile vacuole in Amoeba proteus is considered from standpoints of origin, structure, behavior, and function. The results are obtained from a prolonged study of normal organisms and from their reactions when introduced into conductivity water.The origin of vacuoles is studied by means of dark‐field illumination which reveals the vacuole to be formed from a fusion and coalescence of extremely minute droplets.The retaining ‘wall’ of the contractile vacuole is not a permanent structure, but is in the nature of a condensation membrane, totally disappearing with each contraction.The loci of the contractile vacuoles are not permanent, but vacuoles are formed more or less at random. It is unlikely that they are supported in gelated areas, for amoebae with a dozen vacuoles are quite active and there is no interference with amoeboid movement.Conductivity water increases the size, number, and rate of contraction of contractile vacuoles, which suggests that they may function in maintaining an osmotic gradient as well as in the elimination of metabolic waste.
A study of the tonsillar developments in the lingual region of anurans
Authors: Myers Mabel A. 
Published: February 2005

AbstractIn this study the problem of the tonsil is considered in anurans. The common toad (family Bufonidae) is used as the type, and representative species of the other families are compared.In each species representative stages beginning before transformation were selected, and the lingual region of each was sectioned. Some thyroid‐fed toad tadpoles which had prematurely transformed were examined. The investigations led to the following conclusions:

Accumulations of lymphocytes occur in all the families except Hylidae.
A pair of tonsils located on either side of the tongue appear before transformation in Bufo, and persist, increasing in size through old age.
This pair has its developmental origin at or near the cephalic end of pouch II. In no other species examined do the tonsils appear as early; in almost all forms the accumulations are inconstant in occurrence, as are also some in Bufo.
The cells of the ‘tonsils’ are lymphocytes of varying sizes. They arise from the mesenchyme; later their accumulations become sites of lymphopoiesis.
This type of lympho‐epithelial mass is simple in structure and has a greatly thickened epithelium, due to extensive infiltration by lymphocytes. In the connective tissue the vascular supply is abundant.
The differentiation of lymphocytes may be due to a factor of strain, arising through adjustments made during metamorphosis.
Thyroid‐fed toad tadpoles transform, apparently without developing tonsils.