bluuebunny/crossref_metadata_2025 huggingface dataset:
The prolongation of homograft survival time in the platanna, Xenopus laevis laevis (Daudin), by exposure to low environmental temperature
Authors: Simnett John D.
Published: February 2005

The survival of autografts, first set homografts and second set homografts was compared at 9°C and at 25°C in immature but metamorphosed individuals. Exposure to low temperature prolonged the survival time of second set homografts to a lesser extent than that of first set homografts. It is concluded that low temperature prolongs the survival of first set homografts by inhibiting the process of immunological activation rather than by reducing the rate of reaction between sensitized host cells and the graft.
Properties of contractile protein from bovine carotid artery
Authors: Mallin Morton L.
Published: February 2005

A contractile protein was isolated from the cow carotid artery by extracting with a medium containing 0.6 M KCL. The Enzymatic activity of the artery contractile protein resulted in the splitting of the terminal phosphate of ATP.

Abbreviations: ATP for adenosine triphosphate; ATP‐ase for adenosine‐triphosphatase; R.F. for relaxing factor; AM for actomyosin; EDTA for ethylenediamine tetraacetic acid; TCA for tiechoroacetic acid; ηrel for relative viscosity; ηrel ATP for relative viscosity after addition of ATP.

The divalent metals Ca and Mg activated the enzyme with Ca showing the more pronounced activation. In addition to the studies on the ATP‐ase activity other properties were investigated, such as viscosity, solubility in KCL solutions, ATP‐induced synersis and sensitivity to relaxing factor. The properties of the contractile protein were those of actomyosin. The protein resembles uterine actomyosin with respect to its low ATP‐ase activity and its viscosity values of Zη and ATP sensitivity.
The relation between the torpor cycle and heat exchange in the California pocket mouse Perognathus californicus
Authors: Tucker Vance A.
Published: February 2005

The changes in body temperature (TB) associated with the torpor cycle of P. californicus are described by the equation \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{{\rm dT}_{\rm B} }}{{{\rm dt}}} = \frac{{{\rm heat production - heat loss}}}{{\rm K}} $\end{document} where t is time, and K is the heat capacity of body tissue. This equation can be solved after substituting appropriate expressions for maximum and minimum aerobic heat production and heat loss to give theoretical maximum rates of entry into and arousal from torpor.

The measured time course of body temperature and oxygen consumption during entry into torpor compare favorably with theoretical curves calculated under conditions of minimum heat production and maximum heat loss. Thus P. californicus appears able to “switch off its thermostat” so that oxygen consumption during entry into torpor falls almost to the minimum level for a given body temperature. Heat loss during entry into torpor appears to be facilitated by an increase in thermal conductance.

During arousal from torpor, body temperature increases faster than can be accounted for assuming maximum heat production and minimum heat loss. This could be explained by anaerobic heat production and by a decreased thermal conductance resulting from the posterior vasoconstriction typical of arousing hibernators.

Torpor periods of short duration are feasible for P. californicus, for it can enter torpor and arouse immediately thereafter at an ambient temperature of 15° with an expenditure of energy only 55% of that required to maintain a high body temperature over the same period of time. Arousal from torpor at an ambient temperature of 15° requires about 75% of the total energy expended during a ten hour torpor cycle; entry into torpor and torpor itself account for only 9 and 16% of the total energy expenditure, respectively.

The quantitative relations between heat production and heat loss presented in this paper suggest further investigations of the effects of body size on heat production and loss, and of physiological phenomena which alter heat exchange.
The effect of pyridoxal on potassium fluxes in the Ehrlich mouse ascites tumor cell
Authors: Hempling H. G. , Hare Daphne
Published: February 2005

To determine the extent of coupling between the transport of potassium and the transport of amino acids by the Ehrlich mouse ascites tumor cell, we have investigated the effect of pyridoxal on potassium fluxes. We have chosen a low concentration of pyridoxal (1 mM) known to increase the cell to medium ratios for glycine. It was found that pyridoxal reduced potassium efflux and influx in the steady‐state without significant change in oxygen consumption. At normal levels of cell potassium and in the steady‐state, glycine and pyridoxal together had no effect on potassium fluxes. However, when a net gain of potassium occurred as in a transfer of cells from low temperature to room temperature, glycine and pyridoxal together reduced influx, efflux, and net flux of the ion. In addition, glycine alone reduced potassium influx significantly in contrast to its stimulatory effect in the steady‐state. It is suggested that the steady‐state fluxes for potassium are a balance between an active influx and a passive mediated efflux. The active influx may be reduced in the presence of glycine while pyridoxal may exert its predominant effect on the passive efflux. To explain the stimulation of the influx and efflux of potassium by glycine in the steady‐state, it is hypothesized that the ion makes use of an exchange system for potassium under circumstances where glycine prevents the use of the pathway of active influx.
The action of bile salts on fluid and glucose movement by rat and hamster jejunum, in Vitro
Authors: Faust Robert G. , Wu Shih‐Min Liu
Published: February 2005

Everted sacs of rat and hamster jejunum were used to measure, simultaneously, fluid and glucose movement in the presence of various concentrations of bile salts. Low concentrations of sodium taurocholate or glycocholate did not affect the rates of fluid absorption or transport by either rat or hamster jejunum. Under these conditions, in some cases, while glucose absorption was unaffected, glucose transport was inhibited. High concentrations of bile salts reduced fluid and glucose absorption and transport by both rat and hamster jejunum. Although the transport of glucose against a concentration gradient is completely inhibited at low concentrations of bile salts with rat jejunum, it still occurs with hamster jejunum even in the presence of high bile salt concentrations. In the absence of glucose in the incubation medium, the rates of fluid absorption by rat and hamster jejunum were greatly reduced. Under these conditions, fluid transport by rat jejunum was completely abolished, whereas fluid transport by hamster jejunum was greatly reduced, but not completely inhibited. However, addition of bile salts to the glucosefree incubation medium did produce a complete inhibition of fluid absorption and transport by both rat and hamster jejunum. Bile salts, within the concentration range used in this investigation, have no effect upon glucose utilization and lactic acid production by either rat or hamster jejunum. Sodium taurocholate and glycocholate, at the low concentration of 1 mM, reduced the ATP levels in both rat and hamster jejunal sacs. This reduction of ATP levels in whole sacs was also observed to occur in the mucosal layer in the presence of low concentrations of bile salts. A greater reduction in tissue ATP levels was observed when the bile salt concentration was increased. The amount of ATP in unincubated rat and hamster jejunum was reduced by approximately 40% when incubated in bicarbonate saline containing glucose. Tissue ATP levels were also reduced when sacs were incubated in a glucose‐free medium, a greater reduction being observed in rat jejunum. In the absence of glucose, bile salts were capable of decreasing ATP levels in hamster, but not in rat jejunum. The effects of bile salts on fluid and glucose movement by rat and hamster jejunum were discussed in relation to tissue energy sources for these processes. Also, the possible role played by bile salts in regulating the transference of various substances across the intestinal wall was discussed.
The effects of temperature on gustatory response of rats
Authors: Yamashita Satoru , Sato Masayasu
Published: February 2005

Impulse discharges in the chorda tympani nerve of rats to stimulation of the tongue by NaCl, KCl, CaCl2, HCl, quinine and sucrose at varying temperatures were recorded using an integrator. The tongue had been preadapted to temperature of stimulating solutions so as to eliminate thermal response. The magnitude of response to all kinds of stimuli except for sodium salts of 0.01 to 0.03 M was increased with a rise in temperature from 10° to 30°C and declined from 30° to 45°C, indicating the greatest magnitude at about 30°C. The response magnitude for 0.01 M NaCl was decreased with a rise in temperature from 10° to 45°C. The threshold for NaCl rises with a rise in temperature. Q10 values for the magnitude of response to 0.03 M to 1.0 M NaCl, KCl, CaCl2, HCl, quinine and sucrose are less than two between 10° and 30°C, −1.1 to −1.9 between 30° to 40°C and −1.8 to −3.4 between 35° and 45°C. Sucrose, HCl and quinine gave greater Q10 values than did NaCl, KCl and CaCl2. From such small Q10 values it has been concluded that the reaction between taste receptors and stimuli, which ultimately leads to initiation of gustatory impulses, is of physical nature rather than enzymatic one.
Studies on sympathetic B and C neurons and patterns of preganglionic innervation
Authors: Nishi S. , Soeda H. , Koketsu K.
Published: February 2005

The sympathetic ganglion of the toad consists of two kinds of neurons, the sB and sC neurons of which axons are the B and C fibers, respectively. The sB neurons receive a monosegmental innervation of preganglionic B fibers whereas the sC neurons receive mono‐ or multisegmental innervation of preganglionic C fibers. The pre‐ and postganglionic neurons are divided into a fast (sB neuron) and slow (sC neuron) conduction system. The conduction velocity of the preganglionic axons is proportional to that of the synaptically connected postganglionic neuron axons in the sB and sC neuron systems. In the sB neuron system, the conduction velocity of the preganglionic axons is faster than that of the postganglionic fibers. The relation is reversed in the sC neuron system. The antidromic and orthodromic responses as well as the electrical membrane properties of sC neurons were analyzed and compared with those of the sB neurons. In both neurons, the time constant of the synaptic potential decay was always longer than that of the membrane. The synaptic potentials of sB and sC neurons were abolished at the membrane potential levels of −10 mv and −7 mv on the average, respectively, which indicates that the equilibrium potentials of these neurons are almost the same. The changes in the excitability of the soma as well as axon of the sB and sC neurons after a single response and the response of the sB and sC neurons to a long cathodal current were analyzed and compared.
The attachment of glycolytic enzymes to muscle ultrastructure
Authors: Amberson William R. , Roisen Fred J. , Bauer Adelia C.
Published: February 2005

The glycolytic enzymes, lactic dehydrogenase and aldolase, usually thought to be freely dissolved in the sarcoplasmic matrix, are in good part attached to the muscle ultrastructure. This attachment becomes manifest when the enzyme activities and specific activities of the press juices of whole skeletal muscles (rabbit) are compared with those of minced muscles, all obtained by ultracentrifugation of the tissues at 40,000 xpm for 16 to 20 hours. Mincing causes a great increase in the activities, associated with a rise in the volume and protein concentration of the press juices. We interpret these increases to be due to the solution in the matrix of enzymes previously attached to the ultrastructure.

The same conclusion is reached by a different method, which we call “washing the ultrastructure.” It consists in multiple centrifugations of whole skeletal muscles, and removal of press juices, alternating with periods of imbibition of a buffer (0.1 M phosphate at pH 7.5) too dilute to dissolve out the fibrous proteins. During the imbibitions enzymes diffuse out into the buffer not imbibed, which becomes an extract. After four centrifugation‐imbibition sequences in as many days nearly all of the fluid matrix has been replaced by buffer. Enzyme activities fall steeply in press juices and extracts until nearly all freely dissolved enzymes have been washed away. Homogenates of the pressed muscles then show activities which are about half of those found in the homogenates of unpressed control muscles. We conclude that the enzymes found in the homogenates of the pressed muscles have previously been attached to the ultrastructure.

Similar experiments with heart muscle indicate that nearly all of these enzymes are normally attached to the ultrastructure. Press juices contain only traces of activity, even after the heart has been minced. A fraction of the enzymes is slowly detached during the centrifugation‐imbibition sequences, appearing mainly in the extracts.
The effect of carcinogenic hydrocarbons on rodent and primate cells in vitro
Authors: Diamond Leila
Published: February 2005

The effect of polycyclic hydrocarbons on rodent and primate cells in vitro was studied using dimethyl sulfoxide as the initial solvent for the hydrocarbons prior to their addition to the cell cultures. Because the dimethyl sulfoxide was not toxic to the cells at a final concentration in which relatively high concentrations of the hydrocarbons remained in solution in the medium, the effects of the compounds could be measured quantitatively.

The carcinogenic hydrocarbons, benzpyrene and methylcholanthrene, but not the non‐carcinogenic hydrocarbon, pyrene, inhibited the multiplication of normal embryonic cells from several rodent species. However, concentrations of the carcinogens as high as 10 μg/ml did not affect the growth of virus‐transformed or malignant cells from these species.

In contrast to the differential cytotoxic response of normal and malignant rodent cells to the carcinogenic hydrocarbons, the multiplication of normal, as well as transformed, monkey and human cells was not inhibited by benzpyrene or methylcholanthrene at concentrations of 10 to 20 μg/ml. Organ cultures of human embryonic skin initiated and maintained for ten weeks in medium containing 5 μg benzpyrene/ml showed no abnormalities in the growth rate or morphology of the fibroblasts that grew out of the explants.
Penetration of non‐electrolytes through animal integuments
Authors: Buerger A. A. , O'Brien R. D.
Published: February 2005

The rates of penetration were studied of three non‐electrolytes (DDT, Famphur, dimethoate) through the integuments of six animals (Tenebrio molitor, the meal worm adult; Gryllus domesticus, the house cricket; Periplaneta americana, the cockroach; Bufo woodhousei, the garden toad; Anolis carolinensis, the Carolina chameleon; and Phrynsoma cornutum, the Mexican horned toad). The non‐electrolytes were selected with the intention of varying the polarity widely. The olive oil‐water partition coefficients of the above compounds were 199, 19.2 and 0.593. The compounds were applied in 1 μl drops of acetone. In all cases, an initial very brief period of extremely rapid penetration was followed by a long period of much slower penetration. Penetration during the period of rapid penetration was too fast to be resolved by the method used. Penetration during the slower period always followed first order kinetics. During the second slower period, the greater the polarity of a compound, the more rapidly it penetrated into every animal studied but Gryllus domesticus.
The significance of post‐irradiation growth in regenerating limb and tail blastemas of Amblystoma larvae
Authors: Pietsch Paul , Bruce A. K.
Published: February 2005

Regenerative growth was studied in limbs and tails exposed to x‐radiation. Significant increases in size were observed following irradiation. Growth eventually ceased in irradiated regenerates and involution set in progressively to claim most of the tissue distal to the amputation plane. This growth was accomplished in spite of severe curtailment of DNA synthesis. On a relative basis the amount of growth was independent of the post‐amputation age of the regenerate at time of exposure to x‐rays. Growth following irradiation showed some dose dependency, but this did not become manifested until after an appreciable time‐lag.

It was concluded that at any given moment in the history of the salamander limb or tail there are sufficient numbers of cells capable of forming a blastema without their first having to pass though a phase of high radio‐sensitivity and that these cells are sufficient to account for the aggregation or enlargement of a blastema, independently of normal proliferation.
The effect of efferentiectomy and orchidectomy on the metabolism of the epididymis of the mouse
Authors: Elliott Paul R.
Published: February 2005

The purpose of the study is a comparison of respiratory metabolic rates and anaerobic glycolytic activity (lactate accumulation) in homogenates of epididymides from normal, orchidectomized and testosterone replaced‐orchidectomized mice. Animals subjected to vasa efferentiectomy were used to furnish sperm free homogenates as controls for the homogenates from orchidectomized animals, and to furnish estimates of the contribution of the spermatozoa to these metabolic parameters in homogenates of normal epididymides.

Efferentiectomized mice yield homogenates with a significantly lowered rate of respiratory activity (30%). Experiments with fractions of these homogenates showed this reduction in activity to be equivalent to the contribution of the spermatozoa in homogenates from normal mice. No significant difference in the rate of respiratory metabolism was observed among homogenates obtained from efferentiectomized, orchidectomized, testosterone replaced‐orchidectomized, or testosterone injected‐efferentiectomized mice.

Efferentiectomy also resulted in a lowered rate of anaerobic glycolytic activity in vitro. No further reduction or elevation of this activity was observed in homogenates from orchidectomized or testosterone injected animals. Further study indicated this loss following efferentiectomy to be due to a reduced glycolytic activity in the epididymal epithelium rather than to the absence of spermatozoan contribution to the metabolism.

The evidence presented supports the hypothesis that the presence of some component of the spermatozoa or the fluids in which they reside controls the activation or inhibition of a segment of the lactic dehydrogenase activity which is responsible for the secretion of lactic acid into the epididymal canal for spermatozoan utilization.
Studies on kidney tubulogenesis VI. Survival and nucleic acid metabolism of differentiating mouse metanephrogenic mesenchyme in vitro
Authors: Vainio Tapani , Jainchill John , Clement Keith , Saxén Lauri
Published: February 2005

Results obtained from analysis of the early development of embryonic cells under tissue culture conditions apparently reflect both true developmental events and artificial changes consequent upon the isolation and transplantation of the tissues. The magnitude and mechanisms of such changes were examined in a model system, the differentiating metanephrogenic mesenchyme of mouse embryos, which we have used for several analytical studies in developmental biology. The results indicate that isolating and transplanting this tissue to organ culture conditions causes a marked decrease in nucleic acid metabolism, as measured in incorporation experiments. This lag period extends through the first 20 to 30 hours of in vitro cultivation, after which normal metabolism is restored. The change does not seem to be related to cell loss, since viability counts reveal only a small percentage of cells to be dying during this period. Adding Zn++ ions to the culture medium had a favorable effect on the incorporation of nucleic acid precursors during the lag period, suggesting that the enzyme treatment employed during isolation might have removed bivalent cations from this tissue.
Rhabdom structure and receptor potentials in single crayfish retinular cells
Authors: Eguchi Eisuke
Published: February 2005

The effects of continuous darkness and abnormal ionic ratios (excess Ca+ +, Mg+ +, K+, and absence of Na+) on the fine structure of the rhabdoms and on the intracellular retinal receptor potentials were studied in crayfish compound eyes. The normal rhabdom has its constituent microvilli regularly arranged in a characteristic cross‐banded pattern. The normal retinular cell response consists of an initial transient peak and a sustained plateau. After the crayfish were kept for three months in the dark, the regular arrangement of rhabdom microvilli was markedly upset, and receptor potentials of retinular cells in the eye consisted only of the slow phase. The initial phase of the intracellular retinal receptor potential is more labile than the sustained phase (plateau) and was easily abolished if the rhabdom was so strongly affected by continuous darkness, excess Ca+ +, and excess K+ that the fine structural arrangements of microtubules were destroyed. Since receptor potentials were recorded from compound eyes in which rhabdoms were deranged and almost all their microvilli torn off from the retinular cells, transmission of visual excitation from rhabdom to retinular cell soma must be possible without direct membranous connection between them.
Conjugation of paramecium multimicronucleata, powers and mitchell
Authors: Landis Eugene M.
Published: February 2005

Microscopic examination of both living and stained forms indicates that the so‐called ‘multivacuolate’ and ‘amicronucleate races of Paramecium caudatum’ belong to the species Paramecium multimicronucleata. The published accounts of the morphology and cultural characteristics of the various forms are compared and provide additional evidence. A more complete description is given, including distinctive characters previously omitted.

The conjugation process of P. multimicronucleata in general resembles that of P. caudatum, most of the differences being due to the presence of four micronuclei instead of one. These each divide twice with characteristic figures, twelve of the sixteen daughter nuclei then degenerating. One of the remaining four splits to form a single pair of functional pronuclei in each cell. The two migratory pronuclei interchange as in P. caudatum. The synkaryon divides three times, and probably seven of these nuclei degenerate. The remaining one apparently undergoes two divisions. In most cases by six to eight hours after the conjugants separate two micronuclei of the four thus produced form enlarged macronuclear anlagen, the other two remaining as micronuclei. Each anlage divides within the next two or four hours, producing four macronuclear and four micronuclear analagen. Two fissions, each preceded by a division of the micronuclei, restore vegetative conditions.

The process described above is compared with conjugation in P. bursaria, P. caudatum, and P. putrinum.
A study of the gastric glands of alligator mississippiensis
Authors: Staley Forest H.
Published: February 2005

A review of the literature of the gastric glands of reptiles shows marked differences of opinion concerning the nature and character of the cells composing the gastric glands.

The present investigation of the gastric glands of the alligator has been carried out by histochemical and physiological experiments, rather than by the usual morphological methods, but the results can be stated both in terms of structure and function.

The surface epithelial cells and those lining the gland pits in the fundic, cardiac, and pyloric regions of the stomach of the alligator are not strictly comparable functionally to the mucous cells of mammals.

The cells composing the necks and bodies of the glands in the fundus, according to histochemical reactions, are parietal cells.

Certain cells lying beneath the columnar epithelial cells lining the lumen of the stomach and the foveolae react to one method of fixation and staining as do the chief cells of mammalian material.

The results of the experiment with the vital dye, neutral red, show that the cells of the gastric pits, the necks and bodies of the glands in the fundus of the alligator's stomach, react identically as those of the mammalian stomach.

The gastric juice of the alligator is acid to litmus‐paper and contains a free mineral acid.
Experimental and cytological studies on bisexual and hermaphrodite free‐living nematodes, with special reference to problems of sex
Authors: Honda Hikokuro
Published: February 2005

Hermaphroditic gonads of Rhabdites elegans can be distinguished in early developmental stages, but oogonia cannot be told from spermatogonia. Certain peculiar males show developmental processes approaching those of hermaphrodites. More eggs are produced by a hermaphrodite than there are sperm with which to fertilize them. Such exhausted hermaphrodites may be mated with males and produce fertile eggs, but convincing evidence of cross‐fertilization is lacking. Unmated females of Diplogaster aerivora live longer than mated ones, but no difference was found in the males. Sexual instinct seems to be lacking in males of R. dolichura and R. elegans.

Hermaphrodites mated with males produce many more male offspring than by self‐fertilization, but these do not exhibit sexual instincts. Females produced by cross‐fertilization are not pure females, nor have they been found at all in R. elegans or R. dolichura. After fertilization in these two species, both polar bodies are formed and the pronuclei fuse. Sex is determined by the form of sperm.
The histogenesis of cartilage and bone in the long bones of the embryonic fowl
Authors: Fell Honor B.
Published: February 2005

The development and cytology of cartilage and bone in the limbs from the fifty‐second hour of incubation to the first day after hatching are described.

The chief points of interest arising from this study are: (1) Chondroblasts when liberated during cartilage resorption die and disintegrate. (2) All the long bones possess structures which, though not undergoing independent ossification, are homologous with the mammalian epiphyses. (3) Endochondral ossification occurs only in the epiphyses and ends of the diaphyses. (4) The marrow cavity contains multinucleated giant cells which appear to be formed by the fusion of degenerating cells.
The formation of the sex glands and germ cells of mammals I. The origin of the germ cells in the albino rat
Authors: Hargitt Geo. T.
Published: February 2005

An early segregation of germ cells and migration through a germ track into the gonad does not occur in the albino rat. The germ cells are produced only from the peritoneum of the genital region and their earliest formation is coincident with the thickening of the coelomic epithelium to form the genital ridge. This takes place eleven days after insemination in embryos of approximately 18 somites. Germ cells continue to form from the peritoneum during the early development of the gonad. The peritoneum of this region also produces mesenchyme, smaller cells of the gonads, and the germinal epithelium.

The argument for the specific character of the germ cells in vertebrates and their continuity from the egg is based largely upon assumption, and not upon substantial observations, and must be discarded. Germ‐cell origin is a problem of cellular differentiatio, and not of early segregation.
The histology of the blood of perophora viridis (ascidian)
Authors: George W. C.
Published: February 2005

The blood of Perophora viridis is found to contain six types of cells: (1) Green cells, which have green‐colored fatty bodies embedded in clear cytoplasm. (2) Orange cells, with orange‐colored bodies of unknown composition in the cytoplasm. (3) Colorless berry‐like cells, with fluid‐filled vesicles in the cytoplasm. (4) Granular amoeboid cells. (5) Compartmental amoeboid cells, which have box‐like vacuoles containing brownian granules of a fatty substance. (6) Vesicular, signet‐ring type of cell having a single large vacuole. The cytological structure of these cells and their reaction to various dyes are described.

An effort has been made to homologize the types of cells found in the blood of other ascidians with those found in Perophora.

It is concluded that the variety of colors found in the cells of ascidian blood is due to the varying chemical states of the vanadium‐containing chromogen present in the cells.
The nature and inheritance of webbed toes in man
Authors: Straus William L.
Published: February 2005

Webbing of toes or fingers in man is produced by a local arrest of development, causing retention of the normal embryonic webbing. This type of digital fusion involves only the skin, the skeleton being unaffected. The extensor tendons of the toes may sometimes be fused.

Webbed digits occur normally in some marsupials, rodents, and insectivores, in a number of lemurs and catarrhines, and in the siamang and gorilla. They also may occur in varying degree in other Primates, notably Hylobates. An analysis of five new pedigrees together with those already published demonstrates that webbing of toes in man may be inherited in either a mendelian or sex‐linked manner. In one case this character follows the course of the Y‐chromosome.
The comparative morphology of the secondary sexual characters of elasmobranch fishes. The claspers, clasper siphons, and clasper glands. Memoir IX
Authors: Leigh‐Sharpe W. Harold
Published: February 2005

Sixteen species of the genus Scyllium are here considered and arranged in groups according to the accessory structures present on the claspers as follows:

Canicula, sufflans, ventriosum.

Catulus, stellare, capense, variegatum (var. pantherinus), umbratile.

Burgerii, hispida, bivium, anale, natalense, edwardsii.

Marmoratum, laticeps.

The structure of the wall of the oviduct and vagina is demonstrated, and it is shown that the epithelium of both is at first columnar, then ciliated in immature specimens; at maturity that of the vagina further undergoes by transitions a change to stratified. The walls are highly vascular, but contain no special glands.
The comparative morphology of the secondary sexual characters of elasmobranch fishes. The claspers, clasper siphons, and clasper glands, together with a dissertation on the Cowper's glands of Homo. Memoir XI
Authors: Leigh‐Sharpe W. Harold
Published: February 2005

The claspers of Centrina are adnate with the pelvic fin and bear a spine as in other Spinacidae. Mustelus canis resembles M. lunulatus rather than M. vulgaris. The claspers of Chiloscyllium end in a pointed spike. Pseudotriakis resembles the Carchariidae. The three North American Atlantic species of the genus Raia are considered, and R. laevis and R. erinacea are placed in the pseudogenus containing R. batis, and a new pseudogenus erected for R. ocellata. A gross and histological account is given of the Cowper's glands of Homo, and they are shown to be homoplastic with clasper glands, similar in structure, arrangement, development, and function.
The development of the scales of Acipenser ruthenus
Authors: Sewertzoff A. N.
Published: February 2005

The different kinds of scales characteristic of the adult sturgeon are described and the facts of ontogenesis which throw light on the history of these structures are presented.

The scales of Acipenser are exclusively mesenchymatous and therefore are not morphologically comparable with the placoid scales of elasmobranchs. Salensky ('80) drew erroneous conclusions as a result of failure to study the earlier stages of ontogenesis. Goodrich ('03) has correctly described the ontogenesis of the lepidotrichia.

The original form of ganoid scale was that of an elongated rhomb with a longitudinal crest on its external surface. The various forms of scales of the adult sturgeon have been produced by the differentiation of such a scale by change in size, shape, and the fusion of the different elements.

The conclusions are extended to the entire family of Acipenseridae.
Studies in mammalian spermatogenesis VI. The chromosomes of the rabbit
Authors: Painter Theophilus S.
Published: February 2005

The study is divided into three parts. Part I deals with the chromosome number and morphology in the amniotic cells of rabbit embryos. The number of chromosomes has been found essentially constant in amniotic cells of young, but more variable in older embryos. The somatic number is 44. Part II deals with the chromosomes of race crosses (Flemmish Giant X Polish) in which the homologous chromosomes were found to be alike. Part III deals with spermatogenesis. There are forty‐four chromosomes in spermatogonia, and twenty‐two in primary spermatocytes. The sex chromosomes are of the usual X‐Y type.
Sex and the chromosomes in the domestic fowl (gallus Domesticus)
Authors: Hance R. T.
Published: February 2005

The chromosome number in the domestic fowl is approximately thirty‐five or thirty‐six. It is difficult to determine the exact number, owing to the smallness of the shortest chromosomes of the complex and also to the tendency of the chromomeres to occasionally appear as discrete chromosomes rather than as parts of a whole.

Difficulty experienced in fixing adult testes has prevented a satisfactory demonstration of all stages of spermatogenesis. However, satisfactorily preserved prophases of first spermatocytes have been observed which, together with the large amount of embryonic material available, have made it possible to work out the behavior of the sex‐associated chromosomes with reasonable certainty. Measurements of the chromosomes indicate that the longest chromosome in the cell is single in the female and paired in the male. Two classes of eggs are therefore possible—one with and one without this long chromosome, while all the spermatozoa produced are alike in possessing the long chromatic element. The female is therefore heterozygous and the male homozygous in regard to this chromosome which affords a cytological parallel for the genetic evidence of the heterozygosity of the female.
Evolution of man's erect posture (preliminary report)
Authors: Morton Dudley J.
Published: February 2005

Animal posture cannot be regarded as an actual inheritance, for it constitutes a current physiological interaction between gravity and an organism, according to the structure and physical powers of the latter. Hence, ‘inherited posture’ merely implies that in a given species physical qualifications are congenitally transmitted, which facilitate a certain characteristic position of the body. Evolution of posture, therefore, has inevitably been associated with corresponding evolutionary changes in organic structures.

Evidence furnished by the application of biomechanics to studies of ancient and modern primate structures indicates that man's erectly supported body posture could only have originated from a vertically suspended posture (arboreal).

The fact that the prehuman stem passed through an earlier arboreal and brachiating period is attested to by the grasping character of his hands, the ratio of arm‐body length, the extreme mobility of the shoulder‐joints, as well as the extension of his legs on the body.

The semierect posture of the great apes is not an advance toward human bipedism, but a modern reversion toward quadrupedism.

Postural evidence conforms with the many other lines of testimony which maintain the close relationship of the human and anthropoid stems, and signifies that man has been an erect terrestrial biped since the time of his physical origin.
Synapsis and related phenomena in mecostethus and leptysma (orthoptera)
Authors: McClung Clarence E.
Published: February 2005

Contains a description of the very involved process of synapsis, which is displayed with unusual clearness in Mecostethus. It is found that the homologous spermatogonial chromosomes, already longitudinally split in the telophase, become closely associated while still in the diatene condition. From the proximal end of each pair, which attaches to the karyotheca, there spins out a delicate thread. Meanwhile the distal, heavy portion of the spiral, double rod executes a loop so that the proximal and distal ends lie near together. Gradually the remaining heavy portion becomes extended until the entire tetrad is in the leptotene condition. In different species of Orthoptera there are variations in the time of association of homologues. The bearing of the facts disclosed in Mecostethus upon the physical characteristics of chromosomes, their movements and changes in meiosis, their individuality and relation to genetical processes are discussed.
The history of the germ cells of cottus bairdii girard
Authors: Hann Harry W.
Published: February 2005

The primordial germ cells are derived from entodermal giant cells which are found first before the gut is formed and later along the ventral and lateral margins of the gut. Some of these cells pass through the lateral mesoderm to a position dorsal to the gut, where they are distinctly recognizable as germ cells. They are then shifted to the gonad region.

Sex could be distinguished first at fifty‐two days. The female sex is indicated by early maturation stages and the beginning of the oviducal groove. The male sex is distinguished by the presence of the sperm duct. No tendency toward juvenile hermaphroditism is apparent.

A portion of the oocytes formed during the first season matures for the first spawning, which takes place at the age of two years. The remainder form a reserve supply, which is increased each year by oocytes formed from dormant oogonia.

Maturation in the male begins in September and continues until spawning‐time in April. Spermatogonia lying dormant within the cysts during maturation give rise to the sperm of the next season.

‘Spermatid masses,’ probably formed by the fusion of spermatids, are found in the cysts with the ripening sperm.

Definitive sex cells in both sexes have their origin only in primordial germ cells. No transition from somatic cells to germ cells was found at any stage.
Factors involved in encystment in the ciliate didinium nasutum
Authors: Beers C. Dale
Published: February 2005

The results of the study of certain factors which affect encystment in Didinium nasutum indicate the following: Absence of food constitutes an adverse environmental condition which induces encystment in approximately 50 per cent of the didinia subjected to it, though the presence of a certain amount of food in the cell body is requisite for encystment. The prevention of encystment for 750 generations does not affect the percentage of didinia which encyst in the absence of food, and hence Didinium does not become progressively more disposed to encystment as generations pass. Conjugation does not affect the percentage of didinia which encyst in the absence of food. Metabolic by‐products of Paramecium inhibit encystment to a striking degree when didinia are deprived of food in the presence of these products. Metabolic waste of Didinium markedly facilitates its encystment in the absence of food. Hay‐infusion culture fluids of different ages have singularly diverse effects on the encystment of didinia in the absence of food; recently prepared infusions inhibit encystment; infusions four to six days old induce encystment in 90 to 100 per cent of the specimens, and infusions seven to fourteen days old, in approximately half of the specimens.
The relation between hydrogen‐ion concentration and encystment in Didinium nasutum
Authors: Beers C. Dale
Published: February 2005

Experiments designed to ascertain the effect of hydrogen‐ion concentration on encystment in Didinium were carried out by depriving didinia of food in mixtures of spring water and buffer solutions whose hydrogen‐ion concentrations varied from pH 5.0 to pH 9.6, and by counting the number of didinia which encysted and the number which remained active and ultimately died of starvation.

The maximum percentage of encystment was attained between pH 6.4 and 8.4, the range in hydrogen‐ion concentration which is also most favorable for the growth of didinia; within this range the encystment rate was practically constant and was about 52 per cent. The solutions having hydrogen‐ion concentrations between pH 6.4 and 5.0, the acid death limit of the race of Didinium used in the experiments, and between pH 8.4 and 9.6, the alkaline death limit, inhibited encystment, the more injurious solutions producing the greater decrease in encystment rate.

The results indicate that the limits of hydrogen‐ion concentration within which Didinium can live are practically the same as those found by Crane for Paramecium (approximately pH 5.0 to pH 9.6). They indicate further that concentrations of hydrogen ions which are unfavorable for the growth of didinia do not facilitate encystment and, in general, that changes in hydrogen‐ion concentration are of little importance in inducing encystment in Didinium.
The cranial musculature of the toadfish (Opsanus tau)
Authors: Pankratz David S.
Published: February 2005

The highly specialized cranial musculature of the toadfish is characterized by the following features:

Absence of intermandibularis and branchiomandibularis muscles.

Presence of levator premaxillaris muscle.

Very large branchial chamber, the outer wall of which is formed by seven branchiostegal rays connected by a strong fascia provided with muscles (oblique levators and adductors).

Highly developed masticator muscles (adductor mandibularis and pterygoids).

The rectus abdominis, sternohyoid, and hyohyoid muscles are attached by a median aponeurosis to the hyoid and basibranchial elements and directly to the hypobranchial cartilages; this muscle complex depresses the buccal floor in opposition to the geniohyoid.

The pelvic fins are in the jugular position.

Two narrow muscles connect the cleithrum with the fourth ceratobranchial.

The cranial musculature is obviously adapted to a carnivorous habit and particularly for increasing respiratory capacity under asphyxial conditions.
Cytoplasmic constituents in the developing egg of Discoglossus pictus Otth
Authors: Hibbard Hope
Published: February 2005

The cytological and histochemical evidence presented in this paper shows the following facts: (1) The mitochondria are not directly transformed into yolk. They may be concerned in its synthesis in so far as they are a factor in the interacting cytoplasmic system, but there are no visible morphological expressions of this functioning. (2) The accumulations of aequeous substances in the cytoplasm in the form of droplets stainable vitally by neutral red, ‘vacuoles,’ are the forerunners of the first yolk. During the building up of the yolk the aequeous droplets become more and more dehydrated and lose their capacity for being vitally stained. (3) These aequeous vacuoles give the impregnation results commonly ascribed to the Golgi apparatus and are interpreted as such. Special emphasis is laid on the question of the identification of the Golgi apparatus. (4) The fat arises de novo in the cell independently of the mitochondria or the vacuoles. It becomes dispersed throughout the cell among the yolk plates, and the lipoidal content of the latter increases at the end of vitellogenesis, when the fatty globules are intimately pressed in among the yolk plates. (5) At a late stage in the growth of the yolk plates there is the sudden appearance of large quantities of glycogen in the perinuclear zone and throughout the cytoplasm.
The anatomy and life‐history of a freshwater mollusk of the genus sphaerium
Authors: Monk Cecil R.
Published: February 2005

A detailed study has been made of the anatomy of one of the fingernail shells, and preliminary observations on the life‐history have been carried out. In its general organization Sphaerium notatum is very similar to the larger fresh‐water lamellibranchs. A gastric shield, crystalline style, and style sac, very similar to those found in the stomach and intestine of Lampsilis, are present. A pair of slender muscles extending from the dorsal side of the body into the gills, and evidently not previously described, have been found. The nervous system consists of the typical three pairs of lamellibranchiate ganglia, with their connectives, accessory ganglia, and nerve fibers. Particular study was given to the statocysts and osphradia, and attention is called to the fact that the function commonly ascribed to the osphradia is incompatible with their position in the roof of the cloacal chamber.

S. notatum, like all the Sphaeriidae, is hermaphroditic and viviparous. The gonads are paired racemose glands lying behind and below the stomach. The sperm‐producing follicles form the anterior portion of each gonad and are somewhat smaller and more numerous than the ova‐producing follicles which form the posterior portion. The young pass through the early stages of development in brood pouches in the gills and are expelled as relatively enormous individuals.

Preliminary observations on the life‐history indicate that reproduction reaches its height in the summer and that fertilization probably takes place during the late summer and fall.
The morphology and physiology of the invertebrate liver and hepatopancreas
Authors: Dorman Henry P.
Published: February 2005

Modifications of the gastro‐intestinal tract of Nereis virens are two dorsolateral esophageal cecums, directed anteriorly and posteriorly from the point of attachment. The cecal and esophageal lumina are continuous. Each cecum is composed of acini, possessing a row of elongated cells, basement membrane, and intima. Fibro‐elastic tissue is present. The elongated cells contain glycogen and fat.

The hepatopancreas of Asterias vulgaris consists of two lobes in each ray, and the numerous acini empty into the bifurcated hepatopancreatic duct which leads into the pyloric stomach. The hepatic cells are columnar and contain glycogen and fat. Pancreatic cells lie in the midregion of the acini.

The lobulate liver of Loligo pealii lies on the ventral surface of the duodenum. A capsular membrane envelops the organ. The acini possess basement membrane, columnar cells, and intima; their lumina anastomose, forming a common duct, which leads into the blind sac. The hepatic cells contain fat.

The hepatopancreas of Melanoplus femur‐rubrum consists of six cecums histologically continuous with the digestive epithelium of the pyloric stomach. Each cecum consists of simple and compound acini which empty into a duct leading to the pyloric stomach. Each acinus possesses basement membrane, columnar hepatic cells, pancreatic cells, and intima. The pancreatic cells occur in islets, usually adjacent to the basement membrane. The hepatic cells contain glycogen and fat.
Developmental factors in teleost hybrids. I. The early mitotic behavior in the cross between menidia menidia notata ♀ and Prionotus carolinus ♂
Authors: Pinney Edith
Published: February 2005

When Menidia eggs are fertilized with Prionotus sperm, the Prionotus chromosomes react in the Menidia cytoplasmic medium just as they do in the cytoplasm of Fundulus eggs. There is lagging, non‐disjunction, and elimination of chromosomes during the early cell divisions. The mitotic behavior of the Prionotus sperm in the Menidia egg also resembles the behavior of the sperm of Ctenolabrus in the same medium. This behavior which was expected from what was known concerning the mitotic behavior of the reciprocal crosses between Menidia and Fundulus and between Ctenolabrus and Prionotus and other intercrosses between the members of these two groups is regarded as a function of the physical state of the egg cytoplasm during the division phase of mitosis. This physical character forms the earliest differential factor in the development of these hybrids and shows no correlation with the width of the cross.

A comparison of nine teleost crosses, in which both the development and the early mitotic behavior are known, with a rough numerical estimate of the width of the cross brought out the fact that development is most successful in crosses between nearly related species if mitosis is normal and in distantly related crosses if mitosis is abnormal. This indicates that nuclear relationship is also a factor in the development of hybrids.