bluuebunny/crossref_metadata_2025 huggingface dataset:
Turbidity and the Polarized Light Orientation of the Crustacean Mysidium*
Authors: Bainbridge Richard , Waterman Talbot H.
Published: April 2021

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

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

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

The 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

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

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

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

A 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

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

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

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

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

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

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

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

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

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

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

“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).”
Amino Acid Absorption in the Locust (Schistocerca Gregaria Forsk.)
Authors: Treherne J. E.
Published: April 2021

Chromatographic analysis of the haemolymph revealed the presence of ten amino acids of which glycine and serine occurred in the relatively high concentrations of 33·2 and 34·6 mM./l. respectively. These two amino acids, together with glutamine (10·9 mM./l.), were selected for the study of absorption from the gut lumen. An experimental solution containing 14C-labelled glycine and serine was injected into the gut lumen and the subsequent changes in concentration and radioactivity of the gut fluid were followed. The uptake of 14C-labelled glycine and serine was shown to occur rapidly in the mid-gut region and especially from the lumen of the caeca. The concentrations of glycine and serine, and also of glutamine, in the caecal fluid were found to increase significantly above their concentrations in the haemolymph, an effect which was paralleled by a relatively rapid decrease in fluid volume. During this time rapid exchange of 14C-labelled glycine and serine between the haemolymph and the gut lumen was demonstrated. On the basis of these observations it was concluded that the net absorption of these substances depended, in part at least, upon the diffusion gradient created by the relatively rapid movement of water into the haemolymph.
The Osmotic and Ionic Regulation of Asellus Aquaticus (L.)
Authors: Lockwood A. P. M.
Published: April 2021

The freshwater isopod Asellus aquaticus can be adapted to media ranging in concentration from 0 · 088 mM./l. NaCl to 200 mM./l. NaCl. In fresh water O.P.1 has a mean value of 150 · 5 mM./l. NaCl. In more concentrated media O.P.I approaches isotonicity with the medium. The mean ion concentrations of the haemolymph of animals in fresh water are Na1 = 137 m-equiv./l., Ch = 125 m-equiv./l. and K1 = 7·4 m-equiv./l. Na and Cl account for most of O.P.I throughout the viable range of haemolymph concentration. Evidence is presented which suggests that the animal is fairly permeable to salts and water. During 8 days’ starvation there is no change in O.P.I, Na1 or Cl1. Sodium and chloride lost from the body can therefore be replaced by active uptake in the absence of food.
The Regulation of the Internal Sodium Concentration of Asellus Aquaticus in the Absence of Sodium Chloride in the Medium
Authors: Lockwood A. P. M.
Published: April 2021

The freshwater isopod Asellus aquaticus has been observed to survive in continuously flowing de-ionized water for up to 16 days. The haemolymph osmotic pressure, and the concentrations of sodium and chloride fall rapidly to about 65% of the normal value and then decrease very slowly until death. Animals loaded to a steady state in 22Na and then washed with de-ionized water lose tracer at a rate which only decreases slightly between the beginning of washing out and the death of the animal. It is suggested that a movement of water from haemolymph to cells as the haemolymph concentration falls may partially account for the maintenance of the haemolymph concentration despite the steady ion loss. Animals loaded for only a short period in tracer before washing out lose about 50-60% of their 22 Na after a few hours in de-ionized water and then show little further loss for a long period. The differences in the tracer loss curves following long-term and short-term loading have been interpreted as indicating that a considerable proportion of the total sodium of Asellus is not in the haemolymph.
The Extra-Haemolymph Sodium of Asellus Aquaticus (L.)
Authors: Lockwood A. P. M.
Published: April 2021

Some 20-30% of the total body sodium of the freshwater isopod Asellus aquaticus is not in the haemolymph. Autoradiography shows that most of this sodium is not uniformly distributed in the tissues but is localized in the cells of Zenker’s organ with lesser amounts in the ovaries, digestive tubules and cuticle. Uric acid is also present in the cells of Zenker’s organ. No evidence is yet available to suggest the function of the sodium in the cells of Zenker’s organ.
Studies on the Exchange and Regulation of Sodium in the Larva of Aedes Aegypti (L.)
Authors: Stobbart R. H.
Published: April 2021

The steady-state exchange of sodium in the 4th instar larva of Aëdei aegypti (L.) has been studied by means of flame photometry and 22Na. The steady-state exchange of sodium between the larva and medium is more rapid in fed larvae (T12 about 10 hr.) than in starved larvae (T12 about 60 hr.). There is no difference between the sodium levels of fed and starved larvae. In both fed and starved larvae about 90 % of the exchange occurs through the anal papillae so these organs must be responsible for about 90 % of the difference between fed and starved larvae in the rate of exchange. Cytological changes in the anal papillae following upon feeding and starvation are described. The results are discussed in terms of possible carrier mechanisms in the anal papillae.
The Sodium Fluxes in the Muscle Fibres of A Marine and A Freshwater Lamellibranch
Authors: Potts W. T. W.
Published: April 2021

Measurements have been made, using 24Na, of the efflux of sodium from the isolated ventricles of Mytilus eduHs and Anodonta cygnaea. In order to determine the efflux of sodium from the muscle fibres it is necessary to correct for the efflux of sodium from the extracellular space. It was not practicable to make such a correction to the results on Anodonta at 15° C. The mean rate constants and effluxes of sodium from the muscle fibres are Mytilus Anodonta at The energy required for sodium extrusion, assuming it is entirely an active process, is: Mytilus Anodonta at
The Form of Beat in Cilia of Stentor and Opalina
Authors: Sleigh M. A.
Published: April 2021

The patterns of beat in cilia of Stentor and Opalina are described. A fibrillar contraction mechanism is suggested to explain the beating of these cilia and of flagella. The diverse forms of beat are thought to result from differences in the relative timing of parts of the contraction process in different organelles. In both types of ciliary beat the effective and recovery phases are in progress simultaneously and are inseparable parts of one continuous contraction process. The average rate of propagation of the contraction wave in Stentor cilia was 844 μ/sec., which is comparable with the rate found in echinoderm sperm tails. In Opalina cilia the rate was much slower at between 20 and 100 μ/sec. The peristomial cilia of Stentor always beat in the same direction, but Opalina cilia may show co-ordinated beat in any direction, and the form of beat appears the same whatever the direction of beat.
Sodium Regulation in the Crayfish Astacus Fluviatilis
Authors: Bryan G. W.
Published: April 2021

In distilled water or artificial tap water with a very low sodium concentration, sodium uptake by Astacus is prevented or reduced and 22Na outflux is subnormal. This is accounted for to only a small extent by reduced renal sodium losses. Sodium-depleted animals replaced in artificial tap water regain sodium in a roughly exponential manner. This is shown by 22Na to be the result of a considerable increase in sodium influx coupled with an increased but lower outflux. Sodium outfiux appears to consist of three components: urine losses, passive diffusion losses over the body surface and what may be an ‘exchange diffusion’ component which is high during high influx and minimal in distilled water. This latter component represents about 30% of sodium exchange under normal conditions. Eyestalk removal did not affect the ability of Astacus to absorb sodium. In starved animals the gills take up most of the sodium absorbed and the gut is relatively unimportant. Silver staining of the gills is a passive process and the cuticle of the branchial filaments of the gill stem is selectively stained. This region would be a suitable site for ion uptake mechanisms.
Internal Factors Controlling the Suboesophageal Ganglion Neurosecretory Cycle in Periplaneta Americana L
Authors: Harker Janet E.
Published: April 2021

Two interacting factors, both following a 24 hr. rhythm, are found to be concerned in the control of the locomotor activity rhythm of Periplaneta americana. When the suboesophageal ganglion is chilled to 3°C., the rest of the body being kept at room temperature, the phases of the neurosecretory cycle are delayed for a period equivalent to the period of chilling. A second cycle, which follows a 24 hr. rhythm, can act as a stimulus to the neurosecretory cycle if the latter is at a stage which responds to a stimulus. If the second cycle affects the neurosecretory cycle the phases of the latter are reset by the stimulus. The phases of the second cycle can be reset by a change from light to darkness while the suboesophageal ganglion is in the chilled state. It appears that the second cycle is immediately reset by the onset of darkness, regardless of the time at which this occurs. The value to the animal, in its natural conditions, of the control of the locomotor rhythm by two interacting cycles is discussed.
A Comparative Study of Gill Ventilation in Marine Teleosts
Authors: Hughes G. M.
Published: April 2021

Movements of the lower jaw and operculum have been recorded simultaneously with the associated pressure changes in the buccal and opercular cavities during breathing of the following species: Trachurus trachurus (L.), Clupea harengus L., Gadus merlangus L., Onos mustela (L.), Crenilabrus melops (L.), Cottus bubalis Euphrasén, Blennius ocellaris L., Trigla gurnardus L., Callionymus lyra L., Pleuronectes platessa L., Microstomus kitt (Walbaum), Conger conger (L.), Syngnathus acus L. In all species ventilation of the gills is achieved by the action of a buccal pressure pump and of opercular suction pumps. The time course of the pressure changes indicates differences in the relative importance of the two pumps which are related to the habitat of the fish. The suction pump becomes of greatest importance in fishes which spend most of their fives on the sea bottom. In several species the differential pressure curve does not include the brief period of reversal in pressure gradient found in most fishes so far investigated. Notable among these species are the two flatfishes investigated and in which there is some evidence for an active opercular valve. In general, the results confirm the validity of Baglioni’s classification of the respiratory mechanisms of teleost fishes.
Sodium Regulation in the Crayfish Astacus Fluviatilis
Authors: Bryan G. W.
Published: April 2021

In Bristol tap water containing 0.4 mM./l. sodium and artificial tap water containing 2 mM./l. sodium, Astacus maintains a blood sodium concentration of about 203 mM./l. This value was not markedly affected by starvation periods of up to a month. Methods of taking small blood and urine samples from individual crayfish at intervals over several hundred hours have been described. Under steady state conditions, curves for the uptake and loss of 22Na by the blood are described by equations derived for a one-compartment system. The volume of this single compartment, which exchanges sodium with the medium, is larger than the actual blood volume by an amount roughly equivalent to the sodium in the tissues. Exchange of sodium between the blood and tissues is probably very rapid. Sodium losses in the urine account for about 6% of the total sodium outflux found using 22Na. The urine sodium concentration of about 6 mM./l. was temporarily increased by conditions such as heavy feeding when the blood may have gained additional sodium. Potential difference measurements across the body surface indicate that the high blood sodium concentration is maintained by active uptake of sodium.
Respiration in the Desert Locust
Authors: Miller P. L.
Published: April 2021

Small mirrors are used to record the movements of the spiracle valves of Schistocerca gregaria, and some general observations are made on the synchronized movements of the spiracles with ventilation. Spiracles 1-3 are shown to alter their positions of opening and closing in different carbon dioxide concentrations, within the pattern of synchronized movements. Modifications of the amount of opening of spiracles 1 and 3 take place as a result of differential contractions of the openers. In spiracle 1 the energy is stored in an elastic system, and the opener does not necessarily make contractions every cycle. Oscilloscope recordings show these reactions, resulting from carbon-dioxide stimulation, are controlled entirely from within the central nervous system and do not depend on any sensory input. The movements of spiracle 2 are controlled peripherally through the direct action of carbon dioxide on the muscle membrane (Hoyle, 1960) and also through a cuticular wide-opening device. The maintained sensitivity of spiracle 1 and the increased sensitivity of spiracle 2 after they are uncoupled from ventilation are discussed. Some remarks are made on the activity of the denervated spiracle 2, and the suggestion is made that it depends on a central core of thin fibres. A central nervous mechanism is postulated which could account for the rhythmic cessation of impulses in spiracle and ventilatory nerves.
Force Exerted by a Single Cilium of Mytilus Edulis. I
Authors: Yoneda Mitsuki
Published: April 2021

An important step toward the understanding of the beating mechanism in ciliary movement would be a quantitative analysis of the mechanical properties of the cilium. As a matter of fact, several measurements have been reported concerning the work done by ciliated tissues (Maxwell, 1905) or the force exerted by the whole organism in ciliate protozoa (Jensen, 1893) and flagellated bacteria (von Angerer, 1919). The present paper will deal with the force which a single molluscan cilium can produce during its effective stroke.
The Absorption of Sodium Ions by the Crayfish, Astacus Pallipes Lereboullet
Authors: Shaw J.
Published: April 2021

Sodium influx and net sodium uptake have been measured for the crayfish, Astacus pallipes, in solutions of a variety of sodium salts. The nature of the anion has no effect on the sodium influx. Sodium influx is related to the external sodium concentration in the same way whether the anion is chloride or sulphate. The net sodium uptake rate from sodium sulphate is 65-100% of that from sodium chloride solutions. In sodium sulphate solutions the sulphate ion does not penetrate. There is no increase in ammonia excretion during net sodium uptake from sodium sulphate solutions. An analysis of the external solution by conductivity and ion exchange showed that during sodium uptake sodium ions are not exchanged for metallic cations and must be exchanged either for ammonium or hydrogen ions without increasing their normal rate of excretion. Sodium uptake may sometimes exceed ammonia production so that hydrogenion exchange may be involved in these cases. The possibility is discussed that sodium ions exchange for either ammonium of hydrogen ions depending on the metabolic activity of the animal.
The Absorption of Sodium Ions by the Crayfish Astacus Pallipes Lereboullet
Authors: Shaw J.
Published: April 2021

The effect of various cations in the external solution on the sodium influx in the crayfish, Astacus pallipes, has been studied. Potassium in concentrations up to 4 mM./l. has no significant effect on the sodium influx from 0·05 mM./l. NaCl solutions. Calcium has no effect on the influx in concentrations up to 1 mM./l. At higher concentrations the influx may be reduced in some cases. Magnesium generally increases the influx by about 30%. The effect is not related to the external concentration. Ammonium ions reduce sodium influx. With an ammonium/sodium concentration ratio of 20 : 1 the influx is reduced to about 20 % of normal. Ammonium ions do not affect the sodium loss rate. Simple substituted ammonium compounds have little effect on the influx. The external hydrogen ion concentration reduces sodium influx if the pH is below 6. At pH 4 the influx is reduced to 20–30 % of normal. A low pH does not decrease the rate of sodium loss. The nature of the specific inhibition of sodium influx by ammonium ions is discussed. It is suggested that the ammonium ions interfere with a normal sodium-ammonium exchange mechanism.
The Absorption of Chloride Ions by the Crayfish, Astacus Pallipes Lereboullet
Authors: Shaw J.
Published: April 2021

The mechanism of chloride uptake in the crayfish, Astacus pallipes, has been investigated. In the absence of chloride uptake, chloride is lost from the animal at a mean rate of 0·8μM./hr./10 g. body weight. This is about 72% of the sodium loss rate. In salt-depleted animals, chloride balance can be maintained at a minimum external concentration of 0·028 mM./l. This is lower than the corresponding value for sodium. In salt-depleted animals, chloride is taken up from sodium chloride solutions above the equilibrium concentration, but at about one-third of the rate of sodium uptake. From potassium chloride solutions the net uptake of chloride is slight or non-existent. The addition of sodium increases the rate of net chloride uptake from KCl. The chloride influx is always high and is similar from sodium and potassium chloride solutions. The influx is much higher than expected from measurements of loss rate and net uptake. Up to 90 % of the influx may be accounted for by exchange diffusion. Activation of the chloride uptake mechanism can be brought about if the animal is made deficient in chloride only. Chloride influx is not increased but the rate of net uptake may now be high and account for 70 % of the influx. Net uptake of chloride by chloride-deficient animals takes place against an electrochemical gradient and chloride is exchanged for other anions, probably bicarbonate.
Some Effects of Temperature and Concentration of the Medium on the Ionic Regulation of the Isopod Asellus Aquaticus (L.)
Authors: Lockwood A. P. M.
Published: April 2021

Some effects of temperature and concentration of the medium on the sodium metabolism of the isopod Asellus aquaticus have been studied. The steady-state haemolymph concentration rises with the temperature in the range 5–24° C. The change is, however, only a few mM./l. over this temperature range. The osmotic pressure (O.P.i) and sodium concentration of the haemolymph (Nai) also rise at temperatures below about 4–5° C. The rate of sodium loss from the body is unaffected by temperature. The rate of active uptake of sodium is increased as the temperature is raised. The rate of active uptake of sodium is related to the haemolymph concentration, rising as the Nai, falls. The Nai, is maintained at the normal level in media containing more than 90 μ.M./1. NaCl. Steady states can also be maintained at reduced haemolymph concentrations in media less concentrated than 90 μM./L It is suggested that the homeostatic mechanism regulating the Nai, under the influence of temperature operates as follows. As the temperature falls there is a greater decrease in the rate of uptake than in the rate of loss and hence the Nai, falls. A fall in the Nai, however, results in a rise in the rate of uptake. Therefore after a certain fall in Nai the loss is again balanced by uptake and a new but lower steady state is reached. It is tentatively suggested that high temperatures may assist some brackish-water species in the invasion of more dilute media.
Some Excretory Processes in the Abalone, Haliotis Rufescens
Authors: Harrison F. M.
Published: April 2021

Experiments were carried out on the abalone, Haliotis rufescens, to discover some of the mechanisms involved in urine formation. Test substances were infused into the blood stream and their concentrations followed in serially taken samples of blood, pericardial fluid and urine from the right and left kidneys. Inulin appears to be filtered since its concentration is essentially the same in samples of blood, pericardial fluid and urine from each kidney. The concentrations of phenolsulphonphthalein and p-amino hippuric acid were considerably higher in right kidney urine than in the other fluids, indicating that this kidney is capable of active secretion. Glucose occurred in lower concentrations in the left kidney urine than in blood and pericardial fluid, suggesting a reabsorption of glucose by this kidney. Dye solutions of T-1824 and other materials infused slowly into the pericardial cavity appeared in the urine of both kidneys, suggesting the presence of two functional reno-pericardial canals ; presence of both right and left canals was verified by dissection and observation. From the results obtained it appears that the primary step in urine formation is filtration of blood through the walls of the atria into the pericardial cavity. This fluid then passes via the reno-pericardial canals into the kidneys where on the right side substances may be actively secreted into it and in the left kidney substances may be actively reabsorbed.
The Giant Fibre Reflex of the Earthworm, Lumbricus Terrestris L.
Authors: Roberts M. B. V.
Published: April 2021

A nerve-muscle preparation including the longitudinal musculature and the giant fibres in the nerve cord of the earthworm is described. Direct stimulation of the nerve cord with single shocks of increasing intensity results in two types of response: (a) a low threshold, very small twitch, resulting from a single impulse in the median giant fibre, and (b) a higher threshold, slightly larger twitch, resulting from single impulses in the median and lateral giant fibres. Both responses are highly susceptible to fatigue. Stimulation of the body surface evokes a much more powerful contraction which is associated with a burst of impulses in the giant fibre. The strength of the contraction depends upon the number of impulses in the burst and this in turn upon the intensity and duration of the stimulus.
Innervation of Locomotor Movements by the Lumbosacral Cord in Birds and Mammals
Authors: Cate J. Ten
Published: April 2021

In earlier experiments (1960) I was able to demonstrate that in pigeons the lumbosacral cord has a high degree of autonomy, and when isolated from the rest of the central nervous system can autonomously co-ordinate walking movements of the hind limbs. A pigeon with the spinal cord transected in the lower thoracic region under normal circumstances can neither stand nor walk ; but when it is placed in a special apparatus (a kind of carriage) so that it is in a normal attitude with the feet resting on the floor it can make genuine walking movements when the hind part of the body is stimulated. It was found essential that the legs be more or less extended and the soles of the feet resting on the floor.
The Dances of Honeybees at Small Zenith Distances of the Sun
Authors: New D. A. T. , New J. K.
Published: April 2021

The dances of honeybees have been studied in Jamaica (18° 00′ N.), Trinidad (io° 38’ N.), and British Guiana (5° 11′ N.) when the sun was near the zenith. When the zenith distance of the sun was less than about io° the orientation of the observed dances deviated, often very widely, from the direction expected if the bees were indicating the angle between the sun azimuth and the food-source azimuth. But the dance angles did not show the wide scattering to be expected from a failure of perception of sun azimuth. They were frequently well orientated, and successive dances often progressively changed direction clockwise or anticlockwise. The dance angles plotted against time gave smooth curves symmetrical about noon, but of smaller maximum slope than the curves of changing sun azimuth. The direction of turning of the dances was often opposite to that expected from the direction of sun azimuth change. Various conceivable explanations are discussed. It is concluded that the dances can best be explained as the result of two control mechanisms : (i) A mechanism which uses all available information about the real sun azimuth and limits the possible dance angles to a certain range. This range becomes increasingly wide the nearer the sun approaches to the zenith. (ii) A mechanism which takes into account the dance directions (or sun positions) memorized for particular times of day, and between successive memorized positions turns the dances through an angle proportional to time. This mechanism is subject to the limits imposed by mechanism (i). This dual-control hypothesis would provide a general explanation of the orientation of honeybee dances. It could explain the orientation of dances at night and when the sky is completely covered with cloud. Evidence is presented that the acuity with which bees can perceive the position of the sun relative to the zenith is not less accurate than 2°–3°. This is a measure of the accuracy with which they can localize a visual stimulus relative to the direction of gravity. The mechanism proposed for orientating the dances would provide a possible means whereby bees might communicate the direction of a food-source by dances which do not indicate the angle between the azimuths of the food-source and the sun.
The Dynamics of Burrowing of Some Common Littoral Bivalves
Authors: Trueman E. R. , Brand A. R. , Davis P.
Published: April 2021

The process of burrowing in the Bivalvia has been studied in a restricted range of species only, notably in members of the Solenacea (Fraenkel, 1927), the Lucinacea (Allen, 1958), and the Veneracea (Quayle, 1949; Ansell, 1962). This previous work, summarized by Morton (1964), makes little reference to burrowing in the common British littoral species and, with the exception of Ansell’s paper, lacks the precision which more modern techniques of recording may give. The object of this research was to study the process of burrowing in detail in Tellina tenuis, Macoma balthica, Donax vittatus and Cardium edule, common littoral bivalves with very different shell shapes and habits.
The Swimming Performance of the Sea-Anemone Boloceroides*
Authors: Josephson Robert K. , March Steven C.
Published: April 2021

Boloceroides can swim orally by repeated aboral-oral flexions of its tentacles which make up over 90% of the weight of the anemone. Tentacles at different distances from the mouth beat slightly out of phase, with more marginal tentacles leading more oral ones. Isolated tentacles occasionally give aboral-oral flexions like those of attached tentacles during swimming. Early in a bout of swimming the stroke frequency is about 1·2 strokes/sec. and the swimming velocity about 1·9 cm./sec. The stroke frequency is slightly higher in small animals than in large ones. The swimming velocity achieved is independent of animal size. In tethered swimming the maximum forward force developed during a stroke increases with animal size approximately as the square of the diameter of the tentacle crown. About 80 % of the forward impulse produced during the effective portion of the stroke cycle is negated by rearward impulse during the recovery portion of the cycle. The average forward force for the whole cycle is only about 5 % of the maximum force.