bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxygen Consumption As a Function of Size and Salinity in Metapenaeus Monoceros Fab. from Marine and Brackish-Water Environments
Authors: Rao Kandula Pampapathi 
Published: April 2021

ABSTRACT
The oxygen consumption in relation to the salinity of the medium has been studied in a marine and a brackish-water population of the prawn, Metapenaeus monoceros Fab. It has been shown that the regression coefficient of oxygen consumption against weight is not the same for media of different salinity and for the two populations. In both the groups of prawns an increase in the oxygen consumption was observed, with a decrease in the salinity of the medium below that of the habitat. But the marine prawns showed higher rates in 50 and 25 % sea water compared to the brackish-water prawns. On the other hand, the brackish-water prawns exhibited a higher rate of oxygen consumption in 100% sea water and in tap water. It is suggested that these differences might be due to (i) an osmotic adaptation, and (ii) the operation of a metabolic homoeostatic mechanism in relation to osmotic regulation.
Surface Characters of Dividing Cells
Authors: Ishizaka Shozo 
Published: April 2021

ABSTRACT
The surface movements during division have been studied by marking the naked surface of the sea-urchin egg with charcoal particles. The contours of the largest optical section, the positions of the particles thereon and the positions of the astral centres are recorded in a series of camera lucida drawings. The drawings are then superimposed, the centre of gravity and spindle axis being used for reference. It is thereby shown that there are two surface rings which remain in the same positions throughout the whole process of division. It is concluded that these rings indicate regions where stresses remain balanced during division.
On ‘The Stationary Surface Ring’ in Heart-Shaped Cleavage
Authors: Dan Katsuma 
Published: April 2021

ABSTRACT
In the foregoing paper, Ishizaka (1958) succeeded in demonstrating the presence of a pair of ring-zones in the cortex of sea-urchin eggs which remain absolutely stationary with reference to the co-ordinates outside the egg through successive changes of the form of dividing ova. The purpose of the present paper is to see whether or not a similar situation exists in the case of cells cleaving in a heart shape ; i.e. in cells in which the cleavage furrow of one side appears earlier than that of the opposite side.
Osmotic and Ionic Regulation in Scottish Brown Trout and Sea Trout (Salmo Trutta L.)
Authors: Gordon Malcolm S. 
Published: April 2021

ABSTRACT
Adult brown trout (Salmo trutta L.) of both sea-run (sea trout) and freshwater stream (brown trout) forms were captured in the vicinity of Aberdeen and acclimatized to full-strength sea water for periods of up to 5 months. Blood serum samples from these fish were analysed for freezing-point depression, chloride, sodium and potassium concentrations. The patterns of regulation of these concentrations are very nearly the same in both forms. Brown trout and sea trout, at least in eastern Scotland, thus appear to be virtually identical in osmotic and ionic regulatory abilities. However, there is a possibility that there is a difference between the two forms with respect to mechanisms controlling blood acid-base balance. The patterns of regulation shown by Scottish fish are the same as those shown by American hatchery fish treated similarly. The different populations of the species seem not to have diverged significantly from one another in this regard after many generations of more or less complete genetic isolation. The species Salmo trutta is strongly homoiosmotic. Internal concentrations are either unchanged or increase by less than 10% above fresh-water levels with long-term acclimatizations to half and full sea water. The brown trout is the first salmonid species known to regulate so well.
Superpregnancy in the Mouse
Authors: McLaren Anne , Michie Donald 
Published: April 2021

ABSTRACT
Weight increase of female mice during pregnancy was studied in normal pregnancies, and also in females of various ages in which superovulation and mating had been induced by gonadotrophin treatment. In some spontaneous and induced pregnancies, the weights of the gravid uterus and of the live embryos were taken at autopsy 1812 days post coitum in addition to the total weight of the intact pregnant female. The main weight increase in both treated and control pregnancies occurred between about 1012 and 1612days post coitum. The weight gain per embryo showed a linear decrease with increasing numbers of embryos, and a linear increase with the 712-day weight of the female. When the data were adjusted to a standard 712-day maternal weight, the total weight gain at first rose with embryo number, but declined when the number of embryos increased above the normal range. The extra-uterine weight increase of the female declined with increasing numbers of embryos. We conclude that female mice carrying abnormally large numbers of embryos economized not only on embryonic growth but also on extra-uterine weight increase. Young mice carrying large litters appeared to use up a large proportion of their fat reserves during pregnancy.
The Physical Properties of the Swimbladder in Intact Cypriniformes
Authors: Alexander R. McN. 
Published: April 2021

ABSTRACT
A method is described whereby certain physical properties of the swimbladder have been determined in intact, unoperated Cypriniformes. These properties are volume, excess internal pressure, extensibility, and relative sensitivity (an index of the rate of change of volume with depth). The mean volume of the swimbladder varies in the twelve species examined from 5.8 to 9.9 ml./100 g. body weight. In most Cyprinidae the swimbladder gases are maintained at a mean pressure 2-3 cm. Hg above that of the surrounding water at the depth to which the fish is adapted. Higher pressures occur in a few species, most notably the bream (10.8 cm. Hg). A much lower pressure is found in Amiurus. An excess internal pressure is probably necessary to provide a taut swimbladder wall to operate Weberian ossicles. The swimbladder wall has non-linear elastic properties such that as the excess pressure in the swimbladder rises the extensibility of its wall falls. The swimbladder also shows slow-elastic properties. The significance of these properties is discussed. Excess internal pressure and low extensibility combine to limit the rate at which the volume of the swimbladder, and so the buoyancy of the fish, changes with depth. For small depth changes the swimbladder of the bream (an extreme case) changes its volume only one-quarter as much as would a free air-bubble.
The Densities of Cyprinidae
Authors: Alexander R. McN. 
Published: April 2021

ABSTRACT
The mean sinking factor of each of eight species of Cypriniformes has been determined by a method involving measurement of the pressure at which anaesthetized specimens float. It was found to lie between 1001 and 1004 for all species except the gudgeon, for which it is 1008. Roach, dace and carp have swimbladdere of very different sizes. It was shown that differences in the weight and density of the skeleton and scales, and in muscle density, are important factors in determining the volume of swimbladder gas necessary for neutral buoyancy. Differences in fat content are unimportant in these fish.
Some Observations on Tick Paralysis in Marmots
Authors: Emmons Patricia , Mclennan H. 
Published: April 2021

ABSTRACT
Infestation with certain species of ticks gives rise in a number of animals to a paralysis which if unrelieved may end in death. The effect of such parasites is felt particularly in the ranching areas of South Africa and along the east coast of Australia, where sheep and dogs respectively are principally affected, and in cattle ranches west of the Rocky Mountains in Canada and the north-western United States. In this last area the condition is produced by the bite of the ixodid tick Dermacentor andersoni Stiles (Gregson, 1953).
The Shadow Reaction of Diadema Antillarum Philippi
Authors: Millott N. , Yoshida M. 
Published: April 2021

ABSTRACT
Light is shown to suppress the shadow reactions of Diadema spines to a degree which varies with its intensity. Inhibition can occur when there is spatial separation between the areas shaded and illuminated in the radial nerve and skin. The degree of inhibition is affected by the position and size of the area lighted. In both skin and radial nerves, uniform meridional gradients of inhibition are found, inhibition being maximal when the areas lighted and shaded are near or coincide, decreasing as these areas are moved apart. The effect of light may be reversed when it is projected at more than a critical distance from the shadow. Gradients in the skin which run parallel to the ambitus, show maximal inhibition at the ambulacral margins, so that the inhibitory gradient corresponds with that of sensitivity to shadows. Interaction between excitation and inhibition may occur in the radial nerve or at the periphery and there are several pathways for excitation and inhibition. The findings are discussed in relation to ‘off’ effects and receptor fields in retinae.
The Response of the Ampullae of Lorenzini of Elasmobranchs to Mechanical Stimulation
Authors: Murray R. W. 
Published: April 2021

ABSTRACT
The ampullae of Lorenzini are sensitive to weak tactile stimulation applied to the ends of their jelly-filled tubes. Either an increase or a decrease in their resting discharge frequency may be caused, each with an opposite after-effect. ‘Adaptation’ is total, being three-quarters completed in 3-8 sec. This ‘adaptation’ probably includes accommodative changes of the tissues. The function of the ampullae is discussed, but no definite conclusion can yet be reached.
Some Factors Affecting the Oxygen Consumption of Asellus
Authors: Edwards R. W. , Learner M. A. 
Published: April 2021

ABSTRACT
The oxygen-consumption rates of Asellus aquaticus (males and females) have been measured at 10 and 20° C. using a constant-volume respirometer, and the effect of starvation for 24 hr. investigated. The oxygen consumption is approximately proportional to the 0.7 power of the wet weight. The rate of oxygen consumption at 20° C. is greater than at 10° C. by a factor of 1-5. The oxygen-consumption rates of A. aquaticus and A. meridianus have been measured at 20° C. in a flowing-water respirometer employing a polarographic technique for the measurement of dissolved-oxygen concentrations. The oxygen consumptions of A. aquaticus and A. meridianus are similar and decrease by 15-20% when the dissolved-oxygen concentration falls from 8.3 to 1.5 p.p.m. The oxygen consumption of A. aquaticus is between 35 and 75 % higher in the polarographic respirometer than in the constant-volume respirometer.
Studies on the Chemical Composition of Muscle Tissue
Authors: Robertson James D. 
Published: April 2021

ABSTRACT
Methods of analysis of muscle are discussed, particularly in regard to ashing and extraction procedures for inorganic ions and the determination of chloride. imultaneous analyses have been made of blood and muscle for the following ions: Na, K, Ca, Mg, Cl, SO4, inorganic and total trichloracetic acid soluble P (inorganic and organic phosphates). In Myxine muscle the ions analysed make up 39-47% (average 42%) of the total osmotic concentration, assuming it to be that of the blood-serum: 491 mg. ions/kg. water content compared with 1181 mg. ions/kg. water in the serum. The latter is practically isosmotic with the surrounding sea water of 1208 mg. ions. Potassium and phosphate are the only ions higher in concentration in the muscle than in the serum, but the muscle concentration of sodium exceeds that of potassium. Low calcium concentrations of 1.8-2.2 mg. ions/kg. water in the muscle and 5.5-7.I mg. ions in the blood serum, compared with 11.1 mg. ions in the sea water, are correlated with the absence of a calcified skeleton. Muscle ions in Muraena come to 308 mg. ions/kg. water content, about 72% of the osmotic concentration of the plasma; the latter is about one-third that of the surrounding sea water. Potassium, calcium, magnesium and phosphate ions in muscle exceed their respective concentrations in the plasma, while the remaining sodium, chloride and sulphate ions are below the plasma values. Cation-anion balance of the analysed constituents of Myxine muscle is satisfactory, but there is a considerable anion deficit in Muraena muscle, probably made up in part by lactate and bicarbonate ions.
Studies on Sodium Balance in Gammarus Duebeni lilljeborg and G. Pulex Pulex (L.)
Authors: Shaw J. , Sutcliffe D. W. 
Published: April 2021

ABSTRACT
The mechanisms of sodium balance in Gammarus duebeni and G. pulex, adapted to various external concentrations, were compared. G. duebeni could be adapted to live in 1 mM/1. NaCl solution and, in some cases, to concentrations down to 0·2 mM/1. G. pulex could survive in concentrations as low as 0·06 mM/1. The sodium loss rate in G. duebeni adapted to 2 % sea water was much higher than in G. pulex but was reduced to about the same level when the animals were adapted to low external concentrations. In both species there was a non-linear relationship between sodium influx and the external sodium concentration. In G. duebeni the uptake mechanism was saturated at an external concentration of about 10 mM/1., whereas in G. pulex saturation was reached at a much lower concentration. The maximum rate of uptake was greater in G. duebeni than in G. pulex. In both species adaptation to low concentrations involved a small increase in the sodium influx and a reduction in the loss rate. The most important factor in the superiority of G. pulex over G. duebeni in surviving at low external concentrations is the high affinity for sodium displayed by the uptake mechanism in G. pulex.
Water Relationships of Aphis Fabae Scop. During Tethered Flight
Authors: Cockbain A. J. 
Published: April 2021

ABSTRACT
Water content varies from 64 to 73 % of the total body weight and 72−76 % of the fatless body weight of 24 hr. old unflown alatae of Aphis fabae. Water loss during flight may be attributed to evaporation and excretion. A mean of 0-07 mg. water is lost per aphid during a 6 hr. tethered flight at 25−26°C. and 57−82% R.H., corresponding to c. 9% body weight; at least 66% of the loss (c. 1 % body weight/hr.) is by evaporation. Excretion during flight is not affected by relative humidity differences over the range 41−75 % at 25−26°C., but the relative amounts of water lost during prolonged flight are inversely related to relative humidity, because of the effect of humidity on evaporation. Proportion of water in the body does not change significantly during tethered flight. Mean percentage water to total body weight increases from c. 68−69 % during 6 hr. ; mean percentage water to fatless body weight decreases from c. 74 to 73 %. Water loss is evidently not a limiting factor to flight in atmospheres of saturation deficit less than c. 23 mm. Hg.
Viability and Fecundity of Alate Alienicolae of Aphis Fabae Scop. After Flights to Exhaustion
Authors: Cockbain A. J. 
Published: April 2021

ABSTRACT
Laboratory-reared 24 hr.-old alate alienicolae of A. fabae were flown for variable periods, but all to apparent exhaustion; their subsequent longevity and fecundity on broad beans, or their survival times during starvation, were compared with controls. Adult longevity, reproductive rate and capacity, and nymph viability were similar in exhausted and control aphids that settled on host plants after flight. Mean adult life was 31 days in exhausted aphids and 32 days in the controls. Both exhausted and control aphids produced an average of 84 larvae per adult. The only major difference noted between exhausted and control aphids that fed after flight was a reluctance, or inability, of exhausted aphids to fly on the following day. Exhausted aphids starved after flight lived for a significantly shorter time (mean of 30 hr.) than control aphids starved without flight (55 hr.). 28 % df the exhausted and 88 % of the control aphids could take-off on the next day. The results indicate that long migratory flights are unlikely to affect the reproductive potential of aphids, and that alate alienicolae of A. fabae, having settled on a suitable host after an exhaustive flight, are unlikely to fly again.
The Relationship Between Nutrition, Hormones and Reproduction in the Blowfly Calliphora Erythrocephala (Meig.)
Authors: Strangways-Dixon J. 
Published: April 2021

ABSTRACT
Calliphora erythrocephala females will live on a sugar diet but will not reproduce unless protein-containing substances are also ingested. If fed protein without carbohydrate, they die. Isolated females were allowed to select from a carbohydrate (sucrose) solution and from a protein-containing solution (Marmite yeast extract in milk) which were contained in identical capillary tubes. The total volume of food ingested each day over a complete reproductive cycle was found to be fairly constant. Within this total, however, ‘protein’ and carbohydrate were selected in quantities which varied with different phases of the reproductive cycle. Thus during the early stages of egg growth, ‘protein’ was ingested in relatively large quantities, while during yolk formation ‘protein’ ingestion declined. Carbohydrate consumption, on the other hand, was relatively low during the early stages but increased during yolk formation. At oviposition the cycles started again. Carbohydrate ingestion of non-reproducing females (fed on sugar solution only) remained at a constantly low level. Selective feeding did not appear to be influenced by mating. Females were found to accept courting males on the day of the first oviposition but not before. This, of course, necessitated a mixed diet of carbohydrate and ‘protein’.
The Action and Composition of the Saliva of An Assassin Bug Platymeris Rhadamanthus Gaerst. (Hemiptera, Reduviidae)
Authors: Edwards John S. 
Published: April 2021

ABSTRACT
The responses of whole insects, selected organs, and tissues to treatment with the saliva of an assassin bug Platymeris rhadamanthus are described. The excitability of muscle and nerve is rapidly abolished. In the general lysis that follows immobilization only cuticular and collagenous structures are spared. The disruption of lipid layers in the walls of nervous tissue is histologically demonstrable at an early stage. The saliva contains at least six proteins, and lacks mucoprotein or other mucoid substance. Three proteolytic fractions were recognized after starch-gel electrophoresis at pH 8·6, one of them forming the major component of the saliva. Attempts to locate a toxic fraction were unsuccessful. The alkaline endopeptidase activity of whole saliva characterized with an azocasein substrate closely resembles gut proteases of other insects examined with the same substrate. Hyaluronidase is present in the saliva and with protease acts as a spreading factor by breaking down the intercellular matrix. Lipase and esterase activity were not detected in the saliva, but gut-wall extracts were lipolytic. The saliva shows weak phospholipase activity. ATP-ase, and serotonin were not detected. The mode of action of assassin bug saliva as a venom and in external digestion is discussed. It is suggested that its toxicity is due to the disruption of phospholipid layers of the cell wall and is the first manifestation of general lysis during external digestion.
The Respiratory Centre in the Tench (Tinca Tinca L.)
Authors: Shelton G. 
Published: April 2021

ABSTRACT
The medulla of the tench brain was searched systematically by means of needle electrodes for rhythmic bursts of action potential activity coinciding with the breathing movements. The neurones which produced these rhythmic bursts of activity were located in the grey matter, mainly beneath the IXth and Xth motor nuclei and in the region round the Vllth motor nucleus. This type of activity was also found in some of the neurones forming the Vth and Vllth motor nuclei. The respiratory neurones were not arranged in a discrete and homogenous nucleus anywhere in the medulla, but were scattered through the grey matter. The distribution was not uniform, the neurones tending to occur in very small groups. There was also a relatively higher density of respiratory neurones in the central, as compared with the more anterior and posterior, parts of the respiratory region. The possibility that variations may occur in the constitution of the respiratory centre, in different individuals and in the same individual at different times, is considered. The manner in which neurones of the respiratory centre function to produce the rhythmic activity is discussed. Localized destruction of active respiratory regions, over a wide area of the medulla in different fish, was never followed by a breakdown in the rhythmic movements. This is interpreted as evidence against the existence of a pacemaker and favouring the hypothesis that the rhythm is produced by a general reciprocal interaction of large numbers of respiratory neurones.
Sodium and Potassium Fluxes in the Abdominal Nerve Cord of the Cockroach, Periplaneta Americana L
Authors: Treherne J. E. 
Published: April 2021

ABSTRACT
The influx of sodium and potassium ions into the central nervous system of Periplaneta americana has been studied by measuring the increase in radioactivity within the abdominal nerve cord following the injection of 24Na and 42K into the haemolymph. The calculated influx of sodium ions was approximately 320 mM./l. of nerve cord water/hr. and of potassium ions was 312 mM./l. of nerve cord water/hr. These values are very approximately equivalent to an influx per unit area of nerve cord surface of 13·9 × 10−12 M cm.−2 sec.−1 for sodium and 13·5 × 10−12 M cm.−2 sec.−1 for potassium jons. The relatively rapid influxes of these ions are discussed in relation to the postulated function of the nerve sheath as a diffusion barrier. It is suggested that a dynamic steady state rather than a static impermeability must exist across the sheath surrounding the central nervous system in this insect.
Osmotic and Ionic Changes in Blood and Muscle of Migrating Salmonids
Authors: Parry Gwyneth 
Published: April 2021

ABSTRACT
Osmoregulation of the Atlantic salmon in fresh water and sea water, and during transfers from one salinity to another, has been studied by measuring the freezing-point and the levels of some inorganic ions in the blood plasma, and water content and ions in whole muscle. An increase in blood concentration of about 12 % follows the transfer of juvenile fish (smolts) from fresh water to sea water; and a fall of concentration of about 5 % follows the transfer of the adult fish from sea water to fresh water. Some changes in analyses of whole muscle indicate changes in the extracellular compartment during transfers from one salinity to another. Osmoregulatory powers of juvenile salmon (smolts) and fresh-run adults are good, but spent fish (kelts) returning from fresh water to sea water, osmoregulate with difficulty or not at all.