bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies On the Respiration of Sea-Urchin Spermatozoa
Authors: Mohri Hideo 
Published: April 2021

ABSTRACT
In the previous paper (Mohri, 1956), it was shown that in sea-urchin spermatozoa, the outburst of respiration which occurs on dilution of a sperm suspension can be suppressed by sodium azide. However, the low respiration which follows the outburst is not affected by this poison, although both are inhibited by cyanide.
The Nerves and Muscles of Medusae
Authors: Horridge G. A. 
Published: April 2021

ABSTRACT
The compensatory movements of Cyanea (Semaeostomeae) and Cassiopea (Rhizostomeae) are described. The asymmetry of these responses is not compatible with the properties of the through-conducting giant fibre net which propagates the contraction wave. Stimulation experiments with Cyanea show that a second nerve net, called the diffuse net, acts locally on the muscles of the bell and delays the process of relaxation. In Cassiopea, the responses of a ring of tissue containing a continuously circulating contraction wave are also evidence of a double innervation. The responses of Nausithose (Coronatae) are described and are interpreted in a similar manner. In all three orders the two nerve nets are in places superimposed but are independent except where they meet at the marginal ganglia. Here the diffusenet acts irreversibly on the rhythmical units, which are known to be within the giant fibre net.
Nitrogenous Excretion by Embryos of the Viviparous Snake Thamnophis S. Sirtalis (L.)
Authors: Clark Hugh , Sisken Betty Florio 
Published: April 2021

ABSTRACT
Functional considerations of the placenta of saurian reptiles are limited virtually to assumptions based on known embryonic requirements and structural placental features (Weekes, 1935). It appeared that the nature of embryonic excretion might profitably be investigated in the garter snake whose young are born alive. The extreme solubility of urea, and the fact that the black snake embryo excretes only 20% of its nitrogenous waste as uric acid (Clark, 1953), suggest the possibility that embryos of a placental saurian reptile might pass urea and ammonium salts to the blood stream of the mother; whether some of the soluble nitrogenous excreta are eliminated through the placenta or whether all nitrogenous excreta are retained in the foetus and adnexa, the degree to which the embryo is dependent upon uric acid is of interest. Accordingly, assays of urea, ammonia and uric acid in the developing embryo were undertaken.
Some Aspects of the Growth of Single and Mixed Populations of Flagellates and Ciliates
Authors: Mučibabić Smilja 
Published: April 2021

ABSTRACT
The effect of temperature has been studied more than that of any other single ecological factor, and its significance for the growth of populations of many species has been known for a considerable period. Previous studies on Protozoa have been confined to the effect of temperature on the rate of division, and so far as is known other aspects of the problem have not as yet been examined. Thus,Woodruff & Baitsell (1911) and Mitchell (1929) examined the effect of temperature on the division rate of Paramecium in cultures containing bacteria. This effect was also studied on Chilomonas paramecium in isolation cultures by Smith (1940),and on Tetrahymena geleii by Phelps (1946). Phelps observed division rates only in the logarithmic phase of growth, and in that work he was not concerned with the effect of temperature on population growth. It seemed worthwhile, therefore, to examine the effect of temperature on the growth of Chilomonas paramecium in greater detail.
Proprioception in Limulus
Authors: Pringle J. W. S. 
Published: April 2021

ABSTRACT
Tonic and phasic discharges of impulses may be recorded in the small leg nerve of Limulus from endings sensitive to the position and movement of the femorotibial and other joints. The nerve fibres originate from the large sensory cells described by Stuart (1953)-Of those at the femoro-tibial joint, one group of cells lies under the hinge and the endings react tonically to the strains present in the cuticle ; some are excited by flexion and some by extension. The other group of cells, lying more internally, have endings in the connective tissue and react phasically only during joint movement. The relationship is discussed between these endings and the lyriform organs of Arachnids and the campaniform sensilla of insects.
Excretion by the Malpighian Tubules of the Stick Insect, Dixippus Morosus (Orthoptera, Phasmidae): Calcium, Magnesium, Chloride, Phosphate and Hydrogen Ions
Authors: Ramsay J. A. 
Published: April 2021

ABSTRACT
The excretion of calcium, magnesium, chloride, phosphate and hydrogen ions has been studied in preparations of single Malpighian tubules isolated in drops of serum under liquid paraffin. The concentrations of calcium, magnesium and chloride are always lower in the urine than in the serum. The concentration of phosphate is always greater in the urine than in the serum. As the concentration of phosphate in the serum increases, the rate of urine flow also increases. The urine is always alkaline to the serum but becomes acid in the rectum. The general problem of excretion by Malpighian tubules is briefly reviewed and discussed.
Visual Responses by Octopus to Crabs and Other Figures Before and After Training
Authors: Young J. Z. 
Published: April 2021

ABSTRACT
Octopuses were fed for some days with fishes in their homes at one end of the tank, and the effect of figures shown at the opposite end was tested. Any small moving object may then be attacked, but the probability of attack is low and the delay long. Crabs and a black horizontal rectangle were attacked more often than other figures. If a figure is withdrawn on the occasions when it is attacked, then the probability of attacks remains low and may slowly decrease. If the octopus is allowed to eat crabs the probability of attacks on them quickly rises towards unity. If food is given when some other figure (say a black vertical rectangle) is attacked, then this figure will later be attacked. An octopus makes attacks more regularly on a figure that has recently been associated with food than on any other figure. This learning to attack a given figure can take place after removal of most of the vertical lobe, but the learning is slower and responses less accurate than in the normal animal. Octopuses from which the vertical lobe has been removed attack crabs more readily than other figures. The system that ensures attack therefore resides elsewhere, probably in the optic lobes. If shocks are given when a previously neutral figure is attacked, then the probability of further attacks on this figure rapidly approaches zero. Attacks on other figures or crabs remain frequent. If the vertical lobe is then removed, no attacks are made on such an originally neutral figure. If a figure that has been associated with food is then rewarded with shocks, the probability of attack falls more slowly than if the figure had been neutral. If the vertical lobe is now removed, the frequency of attacks rises. The memory preventing attack is therefore partly resident in the vertical lobe. The greater the amount of previous training to attack, the more slowly does the animal learn not to attack. This applies also if the training to attack is given after vertical lobe removal. After vertical lobe removal, shocks given when crabs are attacked rapidly reduce the probability of attack if the octopus had not previously eaten crabs while in the laboratory. If such feeding had taken place, the probability of attack falls only slowly without the vertical lobes. The experiments show that information stores associating a given figure with either food or shock can be set up after removal of the vertical lobes but tend to dissipate more rapidly than in a normal octopus.
The Effects of Salinity Changes on the Respiratory Rate of the Prawn Palaemonetes Varians (Leach)
Authors: Lofts B. 
Published: April 2021

ABSTRACT
Palaemonetes varians, variety microgenitor, commonly inhabits only saline water around the British coast. It is, however, abundant in water of extremely low salinity in the Cardiff area, where it occurs in the drainage ditches of farm land adjacent to an area of salt-marsh. Animals from areas of both high and low salinity were subjected, in the laboratory, to a range of salinities varying from pure tap water to concentrated sea water. The rate of respiration at each salinity was measured. The population that inhabited the almost fresh water in the ditches differed physiologically from the salt-water form, although morphologically they were identical. The salt-water population showed a minimum respiratory rate when in a medium of 26‰, NaCI salinity. This was expected, since the animal is isotonic at this salinity and the osmoregulatory work is minimal. The second population respired least when in a medium of 6‰o NaCI. The significance of this is discussed.
Investigations Into the Distribution of Blood in the Heart and Aortic Arches of Xenopus Laevis (Daud.)
Authors: De Graaf A. R. 
Published: April 2021

ABSTRACT
The structure of the heart of Xenopus laevis is described, and the differences between Xenopus and Rana are stressed. A fluorescein-cinematographic method of tracing blood flow and an optical manometer for the measurement of blood pressure in Xenopus are described. The right atrial blood is absorbed into the trabecular meshwork only on the right side of the ventricle. Whereas the output of the right atrium is not, or only in negligible quantities, transferred to the left side of the ventricle, a considerable proportion of the output of the left atrium moves to the right half of the ventricle. The left atrium has a larger output than the right atrium. Almost all the blood expelled from the right atrium is sent to the pulmo-cutaneous arches. The blood from the left atrium is distributed to all the arterial arches and the pulmo-cutaneous arches receive a considerable proportion of this blood. More blood flows through the pulmo-cutaneous arches at each beat than is sent through the carotid and systemic arches together. The rate of flow in the pulmonary circuit is much higher than that in the body circuit. A physiological connexion is demonstrated between the left side of the ventricle and the systemic and carotid arches, and between the right side of the ventricle and the pulmo-cutaneous arches. Pressures in the pulmo-cutaneous arch are consistently lower than in either the carotid or systemic arches. The pressures in the carotid and systemic arches are remarkably similar. There is, therefore, no sound reason for postulating a mechanism in the carotid labyrinths which should maintain a higher pressure in the carotids than in the systemics. The pulse curves in the arches show two waves: the first, major, one produced by contraction of the ventricle, the second one by contraction of the bulbus cordis. The spiral valve may not come into contact with the opposite wall of the bulbus before contraction of the latter. Before that time, i.e. as long as the major propulsive force of the ventricular contraction is not expended, the cavum pulmo-cutaneum is in open communication with the ventricle. The pulmonary veins show a weak pulse, and their pressure is higher than in the hepatic veins. This indicates smaller resistance in the pulmonary circuit than in the body circuit. The selective distribution is neither in agreement with the ‘classical theory’ nor with ideas of random distribution. The forces underlying the selective distribution and the significance of the pattern are discussed.
Periodism and Energy Summation with Special Reference to Flight Rhythms in Aphids
Authors: Johnson C. G. , Taylor L. R. 
Published: April 2021

ABSTRACT
Summer populations of Aphis fabae often show a bimodal flight curve with no flight at night. The teneral period between moulting and flight depends on temperature and can be estimated. Increase in temperature causes the teneral period to shorten and is followed, some time later, by an increase in rate of take-off. This produces the afternoon peak of flight. The morning peak is usually due to aphids which, maturing overnight, accumulate and fly when rising temperature permits. A graphical method is given for constructing flight curves from constant, or observed, moulting rates and the temperature during the teneral period. Population periodicities in which each individual acts only once, are distinguished from individual periodicities in which the same act is repeated by the same individuals. Synchronization is necessary for either type to be evident, and this may be due to rhythmic fluctuations in developmental increments preceding the act, even in short-term periodicities, rather than to behaviour responses. This may apply to rhythms of flight, as in aphids, or of emergence ; to seasonal periodic growth of populations in insects; or to populations of cells in regulatory organs.
Osmotic Conditions During the Embryonic and Early Larval Life of the Brook Lamprey (Lampetra Planeri)
Authors: Hardisty M. W. 
Published: April 2021

ABSTRACT
Observations have been made on the swelling of eggs in tap and distilled water. The rate of uptake of water through the outer membranes and the surface of the ovum fell off sharply within a short time of contact with water. In distilled water uptake into the perivitelline space was very much greater than in tap water, but there were no significant differences in the volume of the ovum itself in these two media. The initial permeability of the ovum to water has been estimated as 0.049 μ3/μ2atm./min., falling after about 7 hr. to 0.003 and remaining at this level for the first 5 days of development. The outer egg membranes are apparently freely permeable to water and ions, and the mean Cl concentration of the perivitelline fluid in the later stages of development was found to be only 2.4 mM/l. Evidence is presented which points to a decrease in the volume of the embryo at some point between gastrulation and hatching. In tap water a contraction of the whole egg was observed from the fifth day onwards. The water content of the embryo at hatching was not very much greater than that of the ovarian egg. After hatching, until the absorption of the yolk, there was a continuous increase in the fresh weight and water content of the ammocoetes. The evidence suggests that the ovarian egg is in osmotic equilibrium with the peritoneal fluid (mean 110 mM/NaCl/l.). During development the osmolar concentration of the total egg fluid was reduced to values similar to those calculated from the known dilution, i.e. 30-40 mM/l. At hatching, the osmolar concentration of the embryo (80 mM/l.) was raised within a few days to 11-120 mM/l. The observed reduction in Cl concentration of the whole egg was much greater than that calculated from the increases in volume. The Cl concentration of the embryo itself was reduced from an initial value of 56 to 15 mM/l. embryo fluid a week before hatching. Determinations of the total Cl content of whole eggs and embryos showed a very marked loss of Cl ions in the two days following fertilization. Within 35 days after hatching the Cl level had been raised by active uptake to about four times the values at the time of hatching."
The Chloride Regulation of the Brackish and Fresh-Water Races of Mesidotea Entomon (L.)
Authors: Lockwood A. P. M. , Croghan P. C. 
Published: April 2021

ABSTRACT
Mesidotea entomon (L.) is found in the Baltic and in certain fresh-water lakes in Sweden. It is believed that colonization of fresh water in this region has taken place since the last Ice-age. In the present work animals from brackish and fresh-water habitats have been compared both in respect of the concentration of chloride in their haemolymph and of their ability to survive in media of various salinities. Both fresh-water and Baltic animals have been found able to survive in Plymouth sea water, the concentration of chloride in their haemolymph being close to the concentration of chloride in this medium. Baltic animals could not be acclimatized to fresh water. Animals from both habitats have the same general level of chloride concentration in their haemolymph when acclimatized to dilute sea water. These results are discussed in relation to the evolution of a fresh-water race from a brackish-water race.
Observations On the Normal Histology and Histochemistry of the Fat Body of the Locust (Schistocerca Gregaria)
Authors: Coupland R. E. 
Published: April 2021

ABSTRACT
The fat body of the locust Schistocerca gregaria is composed of both fat cells and oenocytes. The cells increase in number by mitotic division. Glycogen, proteins and phospholipids are present in all cells but are most abundant in the oenocytes ; the amounts of these substances are less in the adult than in the immature forms, whereas uric acid is more abundant in the adult.
Small mitochondria-like structures (as judged by their staining reactions to Janus Green B and acid-fuchsin-methyl green) have been observed in the cytoplasm of the fat cells, the oenocytes, the Malpighian tubules and the follicular cells of the ovary.
No micro-organisms have been observed.
Components of Nitrogenous Excreta in the Earthworms Lumbricus Terrestris, L. And Eisenia Foetida (Savigny)
Authors: Needham A. E. 
Published: April 2021

ABSTRACT
This work was undertaken initially in order to obtain normal standards of comparison for the pattern of nitrogen excretion during wound healing and regeneration in earthworms. The main interest in the results, for the present purpose, lies in the contrast between the patterns of nitrogen output in the two species. The pattern of excretion in Lumbricus is quite well known, from the studies of Lesser (1908), Delaunay (1934) and his colleagues, and Cohen & Lewis (1949a, b, 1950); there is also some information about Pheretima (Bahl, 1945, 1947) and about some representatives of other classes of the Annelida (see Prosser et al. 1950), but none of these results have anticipated the great contrasts here observed between two rather closely related genera. A certain amount of work has been done also on Allolo-bophora caliginosa (Savigny), but this will not be described in detail.
A Temperature Receptor in the Tarsus of the Cockroach, Periplaneta Americana
Authors: Kerkut G. A. , Taylor B. J. R. 
Published: April 2021

ABSTRACT
This paper describes the electrical responses of the isolated limb of the cockroach following localized warming and cooling. There is a temperature-sensitive region in the pad between the claws, and in the first, second, third and fourth tarsal segments (the arolium and the pulvilli). The preparation becomes more active when the temperature is lowered below 13° C. The activity increases as the temperature drop increases. It thus behaves like a cold receptor. The preparation is sensitive to a drop in temperature of i° C. over the critical range below 13° C. The preparation is stimulated by warming it approximately 5° C. in the range 0-28° C., but the activity lasts for only a short time. Warming the preparation above 30° C. brings about considerable prolonged electrical activity.
Effects of High Hydrostatic Pressures on the Activity of Flagellates and Ciliates
Authors: Kitching J. A. 
Published: April 2021

ABSTRACT
The effects of brief exposure to high hydrostatic pressures, ranging in some cases up to 18,000 p.s.i. (1225 atm.) has been studied in various flagellates and ciliates. Closely related species may react very differently. In general high pressure depresses flagellar or ciliary movement, and in most cases, under the standard conditions of the experiments, all movement soon stopped at 8000-14,000 p.s.i. (544-953 atm.). The pressure required to stop movement was usually near that which caused visible structural damage (Table 1, p. 508). Movement was restored on release of pressure provided that the treatment had not been too drastic. In the case of one peritrich ciliate (Epistilis plicatilis) a moderate pressure (1000-3000 p.s.i., or 68-204 atm.) caused an increase of ciliary frequency, but at still higher pressures the frequency was drastically reduced. There is evidence that behaviour was affected by moderate pressures, quite apart from changes in the intrinsic activity of flagella or cilia. Certain flagellates and ciliates were stimulated to activity by application of moderate pressures, and others became motionless. Spirostomum ambiguum was deprived of its ability to reverse or make the avoiding reaction while at high pressure, and at certain pressures the cirri of the hypotrich Stylonychia mytilus beat in a wild and uncontrolled way. It is suggested that high pressure affects ciliary co-ordinating mechanisms in various Protozoa.
The Growth and Development of Mice in Three Climatic Environments
Authors: Biggers J. D. , Ashoub M. R. , McClaren Anne , Michie Donald 
Published: April 2021

ABSTRACT
Pregnant mice were placed in rooms at three different environmental temperatures: hot, temperate and cold. The hot and cold environments were less favourable than the temperate as judged by incidence of both prenatal and postnatal mortality of the young. The growth and development of the young was studied during the first 4 weeks of life.
Body weight was expressed on the logarithmic scale throughout, and since males were found to be significantly heavier than females the two sexes were considered separately. The inverse relation between body weight and number of mice in a litter, reflecting competition between litter mates, was particularly marked in the cold and was still increasing 4 weeks after birth. In the hot and temperate environments the effect reached a maximum at 2-3 weeks of age.
When allowance had been made for the effect of litter size on body weight, no significant differences in rate of growth or development were found between the mice in the hot and temperate environments. Both growth and development were markedly retarded in the cold."
Chemotaxis of Bracken Spermatozoids
Authors: Brokaw C. J. 
Published: April 2021

ABSTRACTIn the original experiments on the chemotaxis of fern spermatozoids, Pfeffer (1884) inserted small glass capillaries filled with a sodium malate solution into suspensions of spermatozoids, and observed that chemotactic aggregation resulted from precise orientation of the spermatozoids to the gradients produced by diffusion of malate from the open tip of the capillary. More recently, Rothschild (1952) provided definite confirmation of the precision of orientation in a chemical gradient by cinemicrographic records of chemotaxis, using bracken spermatozoids.