bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Osmotic and Ionic Regulation of Artemia Salina (L.)
Authors: Croghan P. C. 
Published: April 2021

ABSTRACT
It has been possible to adapt Artemia to sea-water media varying from 0·26% NaCl to crystallizing brine. In fresh water or distilled water survival is relatively short. The osmotic pressure of the haemolymph is relatively independent of the medium and increases only slightly as the medium is made more concentrated. In the more concentrated media the haemolymph is very markedly hypotonic. In media more dilute than 25 % sea water the haemolymph is hypertonic. In distilled water there is a rapid fall of haemolymph concentration. The haemolymph of nauplii from sea water is hypotonic. The sodium, potassium, magnesium, and chloride concentrations of the haemolymph have been determined. The bulk of the haemolymph osmotic pressure is accounted for by sodium and chloride ions. The ionic ratios of the haemolymph are relatively constant, and very different from those of the medium. The concentrations of ions in the whole animal have been studied. The chloride space is extremely high. Such changes in haemolymph osmotic pressure that do occur as the medium concentration is varied are due more to net movements of NaCl into or out of the body than to water movements. Evidence is collected to show that an appreciable degree of permeability exists. Most of this permeability is localized to the gut epithelium, the external surface being much less permeable. It is clear that Artemia must possess mechanisms that can actively excrete NaCl and take up water in hypertonic media. It has been demonstrated that Artemia can lower the haemolymph osmotic pressure by excreting NaCl from the haemolymph against the concentration gradient.
The Movement of the Spermatozoa of the Bull
Authors: Gray J. 
Published: April 2021

ABSTRACTThe rate at which the spermatozoa of a sea-urchin propel themselves can be expressed, with surprising accuracy, in terms of the form and frequency of the bending waves generated by the tail (Gray, 1955; Gray & Hancock, 1955). The object of this paper is to consider how far this conclusion is applicable to other types of flagellated spermatozoa; those of the bull with their relatively larger heads and thicker tails provide a useful basis of comparison and contrast.
Turbidity and the Polarized Light Orientation of the Crustacean Mysidium*
Authors: Bainbridge Richard , Waterman Talbot H. 
Published: April 2021

ABSTRACT
The influence of the turbidity of the medium on the previously reported directional orientation of the littoral mysid, Mysidium gracile, swimming in a vertical beam of linearly polarized light, has been studied. In carefully clarified sea water the slight preference shown for orientation perpendicular to the polarization plane was not statistically significant. In water made turbid with known amounts of suspended yeast a statistically significant preference for swimming perpendicular to the plane of polarization appeared. This response to the pattern of polarized light illumination appears stronger in highly turbid water than it is in water of moderate turbidity. The mechanism of the observed response seems largely dependent upon discrimination of intensity differences in the light scattered horizontally. These results emphasize the need for careful consideration of the scattering and reflexion artifacts almost invariably present with linearly polarized light.
Nitrogenous Excretion in Crocodiles
Authors: Khalil Fouad , Haggag Gaber 
Published: April 2021

ABSTRACT
In Crocodylus niloticus the liquid urine contains a white deposit. In the present study both the liquid and the deposit have been analysed. For the liquid urine, the following values for percentage of total nitrogen have been found: ammonia, 66·8%; urea, 12·5%; uric acid, 2·3%. For the deposit the corresponding figures are: ammonia, 6·0%; uric acid, 88·6%; urea absent. From the relative proportions of liquid urine and deposit it is calculated that the total excretory nitrogen (liquid + solid) is distributed as follows: ammonia, 25·4%; urea, 4·5%; uric acid, 68·5%. Crocodiles are thus ammono-uricotelic. The view that alligators are ammonotelic derives from analysis of liquid urine only. Uric acid deposits have been noted in the urine of reptiles of many orders and it is probable that they occur also in the urine of alligators.
The Co-ordination of Insect Movements
Authors: Hughes G. M. 
Published: April 2021

ABSTRACT
Although many of the structural adaptations associated with the locomotion of aquatic insects are well known, there are few observations on the details of their propulsive mechanisms. In general, these may be subdivided into those which effect swimming by undulatory movements of the body (Kalmus, 1936; Gray, 1953), by oar-like movements of the legs or wings (e.g. Polynema, Hymenoptera), or by jet propulsion methods involving either the use of a surface active secretion (Stenus, Staphylinidae) or the active expulsion of water from the insect. Of these the use of legs as oars is the most common among adults. In this paper cinemato-graphic analyses are given of two beetles which use this method and of the abdominal and leg movements involved in the jet propulsion of a dragonfly nymph. In addition, some observations are described on the effect of amputating legs on the swimming of Dytiscus. These differ significantly from the observations of Bethe & Woitas (1930) and support conclusions based on a study of cockroach movements (Hughes, 1957).
A Survey of the Enzymes from the Gastro-Intestinal Tract ofHelix Pomatia
Authors: Myers Fay L. , Northcote D. H. 
Published: April 2021

ABSTRACTThe digestive tract of the snail has been isolated and a soluble extract prepared from it and its contents. A quantitative analysis of the proteinases, lipases and twenty different carbohydrase activities present in this extract has been made. Snail galactan was not degraded by the enzymic preparation. The use of the preparation for cytological studies has been discussed.
The Mechanism of Marine Osmoregulation in the Lampern (Lampetra Fluviatilis L.) and the Causes of Its Breakdown During the Spawning Migration
Authors: Morris R. 
Published: April 2021

ABSTRACT
Some fresh-run lamperns can osmoregulate in 50 % sea water (Δ = 0·970° C.), where they can maintain plasma freezing-point depressions of about 0·57° C. An analysis of the mechanism of osmoregulation in these animals shows that it is similar in many respects to that employed by marine teleosts. The lampern swallows sea water and absorbs a solution containing a high proportion of monovalent ions into its blood. It has been calculated that chloride is excreted by an extra-renal route, presumably by means of chloride excretory cells which have been discovered in the gills. The rate of extra-renal loss of water is high and the urine output is negligible. Many fresh-run animals are unable to osmoregulate. In some cases the capacity to swallow sea water becomes reduced, whilst in others the number of chloride excretory cells is diminished—an indication that the extra-renal excretory mechanism is failing. Both of these mechanisms regress simultaneously in some animals.
The Inorganic and Amino Acid Composition of Some Lamellibranch Muscles
Authors: Potts W. T. W. 
Published: April 2021

ABSTRACT
Measurements have been made of the inorganic ion and free amino acid content of a number of lamellibranch muscles. The volumes of extracellular fluid in the muscles have also been determined so that the intracellular concentrations can be calculated. The fast portion of the adductor muscle of Pecten contains about 160 mM. K/kg. fibre water and only 43 mM. Na/kg. fibre water and 34 mM. Cl/kg. fibre water. The potassium and chloride are approximately in a Donnan equilibrium with the potassium and chloride in the blood. In the slow portion of the adductor muscle of Pecten and in the two parts of the adductor and in the byssus retractor of Mytilus, the concentrations of potassium in the fibres are from 150 to 160 mM./kg fibre water, of sodium 73 to 95 mM./kg. fibre water and chloride 94 to 152 mM./kg. fibre water. The potassium and chloride in the fibres are not in a Donnan equilibrium with the potassium and chloride in the blood. The fast and slow fibres of the adductor muscles of Anodonta contain 21 and 17 mM./kg. fibre water of potassium respectively, 5·3 and 7·2 mM./kg. fibre water of sodium, and 2·4 and 5·4 mM./kg. fibre water of chloride. The potassium and chloride in the fibres is not in a Donnan equilibrium with the potassium and chloride in the blood. The fast fibres of Mytilus adductor contain 295 mM./kg. fibre water of free amino acids and 39 mM./kg. fibre water of acid-soluble phosphate compounds. The fast fibres of Anodonta adductor contain only 11 mM./kg. fibre water of amino acids and 19·8 mM./kg. fibre water of phosphate compounds. Mytilus muscles fibres adapt to a reduced blood concentration, partly by an increase in water content and partly by a reduction in the sodium, chloride and free amino acid content. Anodonta muscle fibres adapt to an increased blood concentration, partly by a reduction in the water content and partly by an increased sodium and chloride content. The significance of these results is discussed. It is concluded that the ionic contents of the lamellibranch smooth muscles are consistent with equilibria systems in which the permeability to sodium is significant compared with the permeability to potassium and in which both a sodium and a potassium pump operate.
Wave Propagation Along Flagella
Authors: Machin K. E. 
Published: April 2021

ABSTRACT
The nature of the mechanism which initiates and propagates transverse bending waves along the length of a flagellum has been the subject of discussion for many years. Two possible mechanisms have been advocated: (i) that the flagellum is a passive elastic filament set in motion by an active process located at its proximal end, the propagation of the wave along the filament being the result of its elastic properties; (ii) that actively contractile elements exist along the length of the flagellum. The latter view has received the greatest support, but no definite proof appears to have been established.
The Mechanism of Gill Ventilation in Three Freshwater Teleosts
Authors: Hughes G. M. , Shelton G. 
Published: April 2021

ABSTRACTA study has been made of the respiratory movements of three species of freshwater fish. The time course of pressure changes in the buccal and opercular cavities was recorded and movements of the mouth and operculum plotted from ciné films taken simultaneously. Opening and closing of the mouth precede respectively abduction and adduction of the operculum by about one-fifth of a cycle. The most prominent part of the buccal pressure curve is a positive pressure associated with mouth closing. The size of a negative pressure as the mouth opens is small in the trout but may be relatively large in the tench. Abduction of the operculum produces a marked negative pressure in the opercular cavity of all three species and there is a slight positive pressure during its adduction. The respiratory system is divided into a buccal and two opercular cavities and the concept of gill resistances separating them is introduced. The respiratory cycle is made up of four phases which succeed one another. These are: phase (1) opercular suction pump predominant; phase (2) transition with a reduction in differential pressure between the buccal and opercular cavities ; phase (3) buccal pressure pump predominant ; and phase (4) transition with reversal of differential pressure. With the exception of phase (4), which occupies only about one-tenth of a cycle, the pressure in the buccal cavity exceeds that in the opercular cavity throughout the cycle. It is therefore concluded that water will flow across the gills for almost the entire cycle but may reverse for this brief period. The quantitative relationship between the pressures and the volume of water flowing across the gills during different parts of the cycle will depend upon the properties of the gill resistances.
The Effects of Temperature and of Egg-Laying on the Longevity of Drosophila Subobscura
Authors: Smith J. Maynard 
Published: April 2021

ABSTRACT
The adult life span of Drosophila subobscura has been measured at temperatures varying from 20° to 33° C. A sharp increase in the slope of the curve of log survival time against temperature occurs at temperatures above 31° C. Changes which occur in individuals at 33° C. or above are reversible, at least in part, at 20° C. ; but changes occurring at 30·5° C. are irreversible in the sense that the total survival time at 30·5° C. is not increased by intervening periods at 20° C. Exposure of young adult flies to 30·5° C. for a period of about half their expectation of life at that temperature significantly increases the further expectation of life of females at 20° C. but does not alter the expectation of life of males. Such exposure causes a partial regression of the ovaries of females, a permanent change in their behaviour and a reduction in their rate of egg-laying; exposure does not alter the behaviour or seriously reduce the fertility of males. ‘Ovariles’ females and virgin females live for significantly longer than do normal mated females. The expectation of life of ‘ovariless ‘females at 20° C. is not altered by exposure to 30·5° C. It is concluded that egg-laying accelerates the ageing of females at 20° C., and that the prolongation of life of females exposed to 30·5° C. is due to the reduction in the rate at which such females subsequently lay eggs.
Acid Production after Fertilization of Sea-Urchin Eggs
Authors: Rothschild Lord 
Published: April 2021

ABSTRACT
When sea-urchin eggs are fertilized an acid, the fertilization add, diffuses out of them into the surrounding sea water. A claim has recently been made that the fertilization add may be lactic acid, which is oxidized shortly after its production. There is no significant difference between the amounts of lactic add produced by unfertilized and just-fertilized eggs of Echinus esculentus. The amount of lactic add produced by fertilized eggs of this species is too small to explain the evolution of CO2 observed when the eggs are fertilized in manometer vessels. The sea water round just-fertilized eggs was found to contain markedly less bicarbonate than the sea water round unfertilized eggs, confirming that an acid diffuses out of the eggs after fertilization. There is some evidence that the small quantities of lactic add produced by unfertilized and just-fertilized eggs of this spedes do not diffuse into the surrounding sea water. It is conduded that the fertilization add is not lactic add.
The Adaptability of Mice to High Environmental Temperatures
Authors: Harrison G. Ainsworth 
Published: April 2021

ABSTRACT
The adult morphology of some mammals and birds has been shown to be determined by the temperature at which they are reared (Przibram, 1925; Sundstroem, 1930; Allee & Lutherman, 1940). In particular, mice raised at high environmental temperatures have much longer tails, larger feet, less fur and are usually smaller when mature than mice kept under temperate conditions (Sumner, 1909; Sundstroem, 1922; Ogle, 1934; Sakharov, 1949; Harrison, Morton & Weiner, unpublished). Harrison, Morton & Weiner have shown that the magnitudes of some of these heat responses, i.e. the differences between the environmental forms, are dependent upon the genotype of the animals, but apart from body weight, no exceptions to the above generalizations were found by them.
Seasonal Variation in the Activity of the Thyroid Gland of Yearling Brown Trout Salmo Trutta Linn
Authors: Swift D. R. 
Published: April 2021

ABSTRACT
Seasonal variations in the activity of the thyroid gland in yearling brown trout were measured by two methods ; first, by the changes in thyroid epithelial cell height and, secondly, by the rate of loss of radio-iodine from the gland. Peak thyroid activity was found to occur in spring with a second peak demonstrable by the radio-iodine technique in mid-summer. With the exception of this short burst of activity in July, the activity of the thyroid was found to be inversely proportional to the water temperature. It is suggested that the thyroid is concerned in a temperature-compensating mechanism. It is suggested that the rate of change of the thyrotropic hormone level in the blood determines the mode of response of the gland.
Solute and Water Balance in the Muscle Fibres of the East African Fresh-Water Crab, Potamon Niloticus (M. Edw.)
Authors: Shaw J. 
Published: April 2021

ABSTRACT
An account is given of the normal composition of the muscle fibres of the fresh-water crab, Potamon niloticus. The effect of various dilutions of sea water is considered in relation to the concentrations of a number of the muscle constituents. The water content of the muscle decreases as the blood concentration is increased, but at the higher concentrations the muscle dehydration is not so extensive as expected. There is evidence of a small addition of osmotically active substances to the muscle. Potassium and muscle phosphate compounds behave passively and their concentrations are determined by the muscle water content. The concentration of free amino acids and related compounds may be increased beyond that due to water loss. The addition of these substances to the muscle is not greater than 50-90 mM./kg. water. Sodium enters the muscle when the blood sodium concentration is increased. At blood concentrations not exceeding 450 mM./l. sodium probably only penetrates into a freely exchanging region of the fibre: at higher concentrations sodium may penetrate into the fibre interior. These results are discussed in relation to the adaptability of the cell to increased blood concentrations.
The Effects of High Temperatures on Roach (Rutilus Rutilus)
Authors: Cocking Anthony W. 
Published: April 2021

ABSTRACT
When roach were acclimatized to 20° C. and then subjected to five constant rates of temperature rise, the range of death temperatures depended on the interaction between the opportunity for acclimatization and the exposure to lethal temperatures. At 1/20° C. an hour rise in temperature, roach acclimatized fully, died over the longest temperature range (30-3-35-8° C.) had the highest mean death temperature (32-9° C.) and died over a disproportionate length of time (up to 88 hr.) when compared with other rates. The death temperature range at 1/10° C. an hour was 30-8-32-0° C. (mean 31-4° C.) and at 8/10° C. an hour was 31-5 to 32-9° C. (mean 32-9° C.). Roach cannot acclimatize fully at rates faster than 1/20° C. an hour though some acclimatization takes place at a rate of 8/10° C. an hour. Roach excrete more ammonia as the temperature rises but the increase depends on the rate of temperature rise and is delayed for up to 240 hr. at 1 /20° C. an hour. The behaviour showed characteristic changes. Roach died from the posterior end forwards ; the heart was beating and the gall bladder abnormal when the body was opened.
Sex Behaviour and Sex Determination in Crepidula Fornicata L
Authors: Wilczynski Jan Z. 
Published: April 2021

ABSTRACT
The percentages of males and females in naturally occurring chains of Crepidula fomicata L. were found to be 39% females, 6% ‘transients’ and 55% males. Disconnected males kept in cages in sea water for 9 months re-established the normal sex ratio. Disconnected males were kept for periods of 4-6 weeks at temperatures of 30° and io° C. No significant tendency to change sex was observed. Males were injected with extracts of females. No tendency to change sex was observed. In animals of all sizes from small males to large females both male and female gametes are invariably present together. The gametes of both sexes are polymorphic.
Studies on the Transfer of Fertilized Mouse Eggs to Uterine Foster-Mothers
Authors: McLaren Anne , Michie Donald 
Published: April 2021

ABSTRACT
Post mortem examinations were made at 1612 days post coitum of the uterine contents of female mice belonging to the following five groups: untreated control females; females receiving ‘dummy’ transfers of saline without eggs; females receiving five to ten fertilized eggs (‘low’ group); females receiving fifteen to twenty eggs (‘middle ‘group) ; females receiving twenty-five to thirty eggs (‘high ‘group). All transfers were made into the left uterine horn 212 days after mating the recipient to a fertile male. Genetic markers enabled embryos of donor and recipient origin to be distinguished by eye colour. The transfer operation did not affect the pregnancy rate, nor the implantation rate in the uninjected horn. The yield of live embryos of donor origin showed a systematic improvement in all three groups throughout the 18 weeks of the experiment, rising from about 7% of eggs transferred at the beginning to about 36% at the end. The percentage yield was not affected by the number of eggs transferred. The implantation of transferred eggs was found to inhibit the implantation of native eggs in the same horn, but not in the opposite horn. Embryonic mortality in the injected horn was approximately doubled by the transfer operation, but was unaffected by the number of eggs transferred. These findings are discussed and compared with results reported in an earlier paper (McLaren & Michie, 1956).
The Effect of Posterior Lobe Pituitary Extracts on Blood Pressure in Several Vertebrate Classes
Authors: Woolley P. 
Published: April 2021

ABSTRACT
The blood pressure responses of representatives of various vertebrate classes to pitocin and pitressin have been recorded. No relationships between phyletic position and the type of responses exhibited to pitocin and pitressin were observed. Tolerance is developed to serial doses of pitocin and pitressin in both cold blooded and warm blooded vertebrates.
Physiological Mechanism of Nematocyst Responses in Sea-Anemone
Authors: Yanagita T. M. 
Published: April 2021

ABSTRACT
The nettling response of coelenterate nematocysts (nettling capsules or cnidae), as it occurs in a natural manner, often involves the capsules themselves being cast off from the animal’s body surface. The latter event might be taken as a simple mechanical effect of the tension which is exerted upon the stinging thread when this becomes attached to the struggling victim. Parker & van Alstyne (1932), however, tend to see in it an active participation of the organism. They showed that a solution of ether in sea water caused the cnidae to go out of the acontia of Metridium with their threads still undischarged, and suggested it to be an agent imitating that ‘final step in the nettling operation’.
The Composition of the Blood of the Shore Crab, Carcinus Moenas (Pennant), in Relation to Sex and Body Size
Authors: Gilbert A. B. 
Published: April 2021

ABSTRACT
“The influence of sex and body weight on the concentration of the non-protein nitrogen (N.P.N.) in the blood of Carcinus moenas was investigated. Blood N.P.N. decreased with body size in both sexes until a minimum was reached at a body weight of about 35 g. Thereafter it increased with increasing body weight. For body weights less than 35 g. males had higher N.P.N. values than females; above this weight male values were lower. Statistically these differences were highly significant. Frequency distribution of reproductive activity with body size showed peaks which correspond with those for total ionic concentration (Gilbert, 1959a, b) and with the troughs for N.P.N. Results of the present work have been discussed in relation to those reported earlier for conductivity, total O.P., chloride and sulphate (Gilbert, 1959a, b).”