bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Waterproofing Mechanism of Arthropods
Authors: Beament J. W. L. 
Published: April 2021

ABSTRACT
The relationship between the temperature of the cuticle and its permeability to water has been determined for a number of different terrestrial arthropods. In most of these animals the waterproofing wax loses its great impermeability to water very abruptly at a particular transition temperature; that temperature varies appreciably with the individual, but appears to be characteristic of any one species at a particular age within a particular instar. No change in permeability with temperature was found in Tipula sp. taken from soil, in which the cuticle was greatly damaged ; above 48° C. the permeability of the cuticle of Schistocerca nymphs changes rapidly with increasing temperature, but this change is not abrupt. In the permeability/temperature curves for larvae of Pieris, Tenebrio, Calliphora and Nematus, pupae of Calliphora and adults of Schistocerca, Ixodes and Ornithodorus only one transition discontinuity is found. In all these animals the wax maintains almost constant permeability up to the point of transition, above which permeability increases very rapidly with temperature. Immediately after moulting, Rhodnius nymphs and pupae of Tenebrio and Pieris also reveal only one transition point; this occurs at a comparatively low temperature. But when cement is secreted over the primary wax layer, a second and higher transition point is found which is independent of the first point. The lower transition temperature seems constant in position during the life of an instar, but the upper point occurs at progressively higher temperatures as the instar ages. The evidence suggests that these animals have two special waterproof layers of wax, the one with high transition temperature occurring on the outer surface of the cement. This outer layer could arise by the migration of wax from the primary layer (with lower transition temperature) through the cement to the outer surface, there to lose volatile components and waterproof the surface. In every animal investigated a permanent increase in permeability is produced by heating a wax layer above its transition point; after such treatment no transition point can be found. From calculations of the absolute permeability of the various wax layers, and from the behaviour of the wax, it is suggested that all epicuticular waxes are laid down with some special molecular arrangement and that in very waterproof insects this may extend throughout the thickness of the wax layers; in less waterproof insects only a portion of the wax layer (as in the cockroach) may be specially organized. Very slight mechanical damage promotes increased transpiration through the cuticle. Stationary adsorptive dusts applied directly to a primary wax layer do not affect permeability; applied to wax above the cement, they promote rates of evaporation in excess of the value exhibited by the same cuticle having a primary wax layer alone. This phenomenon is discussed in relation to the distribution of water within the transpiring cuticle.
A Study on the Fibre Diameter and Certain Enzyme Concentrations in the Flight Muscles of Some Butterflies
Authors: George J. C. , Bhakthan N. M. G. 
Published: April 2021

ABSTRACT
Fibre diameter and enzyme content were studied in the flight muscles of butterflies exhibiting various capacities for flight. The flight muscles of the better fliers are composed of narrow fibres, while those of the poor fliers are composed of larger fibres. The fibres in any one muscle are uniform with regard to the size and the content of a few enzymes studied, viz. lipase, acid and alkaline phosphatases, ATPase and succinic dehydrogenase. Quantitative estimation of the lipase activity in the flight muscles of different butterflies showed a remarkable relationship with the insect’s ability to fly and the concentration of lipase in its flight muscles. Good fliers are equipped with larger quantities of lipase than are poor fliers. It is suggested that, like birds and locusts, butterflies also utilize fat for energy during sustained flight.
The Composition of the Haemolymph of the Larva of Drosophila Melanogaster
Authors: Croghan P. C. , Lockwood A. P. M. 
Published: April 2021

ABSTRACT
The osmotic pressure, sodium, potassium and chloride concentrations have been determined in the haemolymph of normal Drosophila melanogaster larvae and of larvae selected to survive on standard medium containing 7% NaCl (‘selected’ larvae). The haemolymph composition of normal larvae developing on standard medium shows features characteristic of pterygote insects. The haemolymph of ‘selected’ larvae developing on standard medium containing 7% NaCl is markedly hypotonic to the medium. There is only a small rise in NaCl concentration. Both normal larvae and ‘selected’ larvae can survive and develop on standard medium containing 7% KCl. The haemolymph of ‘selected’ larvae developing on standard medium containing 7% KCl is markedly hypotonic to the medium. There is a decreased Na:K ratio and a very markedly increased Cl:organic anion ratio. The nature of the mechanisms regulating the haemolymph composition is discussed.
An Experimental Analysis of the Function of the Pseudobranch in Teleosts
Authors: Parry Gwyneth , Holliday F. G. T. 
Published: April 2021

ABSTRACT
The effects of removal of the pseudobranch have been studied in four species of marine fish and two species of fresh-water fish. No evidence was found for any direct effect upon osmoregulation or respiratory exchange. Removal of the pseudobranchs was followed by the darkening of the fish, due to chromatophore expansion, and after some weeks, by the degeneration of the choroid gland in the eye. It is suggested that the pseudobranch produces, or activates, a hormone affecting the chromatophores and that the entry of this hormone into the general circulation is controlled by the choroid gland.
The Co-ordination of Swimmeret Movements in the Crayfish, Procambarus Clarkii (Girard)
Authors: Hughes G. M. , Wiersma C. A. G. 
Published: April 2021

ABSTRACT
Electrical activity recorded in the first roots of the abdominal nerve cord show bursts of activity which accompany rhythmic movements of the swimmerets. These bursts persist when a root is cut distal to the electrodes. Proprioceptive impulses have been recorded from the distal portion of these nerves during passive movements of the swimmerets. They have also been recorded in the connectives during both passive and active movements. Cutting all second and third roots of the abdominal ganglia does not interfere with the rhythmic swimmeret movements of the isolated abdomen. Rhythmic efferent bursts persist in first roots even when only a single first root remains intact in such a preparation. Intermittent bursts are also found in the first roots of a completely isolated cord but their pattern, frequency and phase relationships differ from those recorded in the same roots before isolation was completed. Such bursts are very rare in second and third roots. Stimulation of small bundles of fibres in the circumoesophageal commissure produces well-defined inhibitory and excitatory effects on the discharge of single units in the first roots. One specific bundle found in many preparations, when stimulated at 50/sec., caused a tonic retraction of all the swimmerets which then began to beat rhythmically and continued to do so when stimulation was discontinued. Intermittent bursts in the first roots took place with correct phasing during this stimulation even when the abdominal ganglia were isolated except for their connexion with the last thoracic ganglion. Again, such bursts were absent in the second and third roots. It is concluded that both the inflow from peripheral proprioceptors and intrinsic properties of the central ganglia play essential parts in the co-ordination of the metachronal movements of the swimmerets.
The Effects of Ions and Drugs on Neuromuscular Preparations of Sea Anemones
Authors: Ross D. M. 
Published: April 2021

ABSTRACT
Isolated marginal sphincters of Calliactis and Metridium show little spontaneous activity, but over a limited frequency range give quick facilitated contractions to not less than two stimuli, and slow contractions having latencies of many seconds to multiple stimuli over a wider frequency range. Earlier observations on the effects of ions on whole animals are confirmed and extended. Excess K+ causes spontaneous quick contractions and responses to single stimuli ; excess Ca2+ has no direct excitatory effects, but causes an immense enhancement of the quick response without affecting the slow response to stimulation ; excess Mg2+ abolishes both quick and slow contractions. Most drugs, including acetylcholine and its associates, histamine, and 5-hydroxytryptamine, have no effects on either quick or slow contractions. Important effects occur only with tyramine, tryptamine and adrenaline at concentrations of 1 × 10−5 and 1 × 10−4. No inhibitory drug was discovered. Tyramine has no direct excitatory effects but it greatly enhances the quick facilitated responses without enhancing (and in some circumstances depressing) the slow responses to stimuli. It also causes small responses to single stimuli. Tryptamine causes direct quick contractions of the sphincter, gives quick responses to single stimuli and somewhat enhances both quick and slow responses to stimuli. Adrenaline has no effect on quick facilitated responses but causes direct slow responses and some enhancement of slow responses to stimuli. The effects of ions and drugs are obtained only when they are applied directly to the sphincter region. They do not occur when they are applied only to an attached strip of column. It is noted that the effects of excess K+ and tryptamine are identical, and that the effects of excess Ca2+ and tyramine are also identical; adrenaline stands alone as a ‘slow-excitor’. The physiological significance of the results is discussed in relation to different components of the responding system and to the mechanisms of quick and slow contraction in the sphincters.
Hearing and the Octopus Statocyst
Authors: Hubbard S. J. 
Published: April 2021

ABSTRACT
A detailed study of the anatomy of the octopus statocyst by Young (1960) seemed to indicate that, although the maintenance of equilibrium was likely to be its most important function, the possibility of its participating in the function of hearing could not be ruled out. The work described here was an attempt to test this possibility.
Survival of Goldfish in Presence of Carbon Monoxide*
Authors: Anthony E. H. 
Published: April 2021

ABSTRACT
The importance of Hb for certain aspects of goldfish respiration has been tested by converting it to COHb. Goldfish exposed to 80 % CO and 20 % O2 survived over 24 hr. at 30 ° C., and indefinitely longer at lower temperatures. Routine activity of goldfish over most, if not all, of their thermal range does not depend upon Hb. Removal of dissolved O2 from water under asphyxiai conditions does not depend upon Hb. While the physiological basis of CO2 tolerance curves remains unresolved, it can be said that they do not indicate an effect of CO2 upon Hb. Apparent changes in sensitivity to CO2 that have been ascribed to changes in thermal environment are probably artefacts arising from variation in the solubility of CO2.
Sodium Balance in Eriocheir Sinensis (M. Edw.). The Adaptation of the Crustacea to Fresh Water
Authors: Shaw J. 
Published: April 2021

ABSTRACT
In Eriocheir sinensis active uptake of sodium plays a vital role in the maintenance of sodium balance. At external concentrations down to about 6 mM./l. the active uptake mechanism is fully saturated and the uptake rate just balances the rate of loss, which occurs primarily through the body surface. At lower external concentrations balance may be achieved, at least in part, by the activation of the uptake mechanism. A hypothesis is put forward to account for the mechanism of adaptation of the Crustacea to fresh water. Two main factors are involved: (a) a progressive reduction in the permeability of the body surface to salts and, (b) the acquisition of an active uptake mechanism with a high affinity for the ions which it transports. This hypothesis is discussed in relation to previous theories on the adaptation of the Crustacea to fresh water.
The Spectral Sensitivity of Calliphora Maggots
Authors: Strange Priscilla H. 
Published: April 2021

ABSTRACT
If fly larvae are put on a table by a window they immediately begin to travel away from the light. Turn the table round, and the maggots change direction so as to move directly away from the light again. They travel by a ‘tacking’ process—the head end is extended to right and left alternately, and each time the rear end is drawn after it. The animal moves on a straight course if this process is symmetrical; should a movement of the head bring it into a region of higher illumination or other undesirable condition the head is withdrawn, and a second step made to the opposite side, turning the animal round.
The Influence of Sex and Size on the Osmotic Pressure, The Chloride and the Free Amino Acids of the Blood of the Freshwater Field Crab, Paratelphusa Sp. and the Freshwater Mussel, Lamellidens Marginalis
Authors: Padmanabhanaidu B. , Ramamurthy R. 
Published: April 2021

ABSTRACT
The influence of sex and body size on the osmotic pressure, chloride and free amino acids in the blood of the freshwater field crab, Paratelphusa sp., and the freshwater mussel, Lamellidens marginalis, were investigated. In the crab the osmotic pressure increased in both the sexes to a maximum at about 40 g. in males and at 35 g. in females and then fell with further increase in weight. Throughout the whole size range the males tended to have a higher osmotic pressure. Blood chloride in the crab also increased with weight in both the sexes to a maximum at about 40 g. in males and 35 g. in females and then steadily decreased as the weight increased. In the positive slope of the regression line the females have a higher blood chloride, but in the negative slope of the curve the males have higher blood chloride. The free amino acid content of the blood reached a maximum at about 32 g. in males and 35 g. in females and then gradually decreased as the weight increased. Over the whole size range the males tended to have higher free amino acid content than the females. In the freshwater mussel both chloride and free amino acid content of the blood showed a small but steady increase with increasing weight. This is also reflected in a significant increase in the blood osmotic pressure with increase in body weight.
A New System for Continuous Respirometry of Small Air-Breathing Invertebrates Under Near-Natural Conditions
Authors: Macfadyen A. 
Published: April 2021

ABSTRACT
A new system of respirometry for long-term experiments on small air-breathing invertebrates is described for use in work where changing temperature conditions are essential. There is no reason why the same system should not be used for larger animals. The respirometer is of the Barcroft, compensating type, isolated from the atmosphere, and has provision for temperature equilibration in the two vessels. Oxygen is automatically replenished by electrolysis of copper sulphate solution in the chamber as it is used by the animal and the rate of replenishment is recorded. The main features in design of such an apparatus, its limitations and accuracy are discussed. The accuracy is comparable with that of a Warburg respirometer and the sensitivity, at better than 0·1 mm.3 of oxygen/hour, is about ten times as great. A special control and recording system has been developed in order to reduce expense and simplify the interpretation of the data from six respirometers over long periods. It is shown that the errors arising from temperature changes can be reduced to acceptable levels for most purposes. The apparatus is therefore suitable for use in the study of acclimatization and of responses to rhythmical temperature changes. Examples of respiration records are given which illustrate the possibilities of being able to follow respiration rates through several diurnal cycles. Practical details of construction are given in the appendices.
The Physical Properties of the Swimbladders of Some South American Cypriniformes
Authors: Alexander R. McN. 
Published: April 2021

ABSTRACT
The physical properties of the swimbladders of a variety of Characinoidei, Gymnotoidei and Siluroidei were investigated and found to be essentially similar to those previously reported for Cyprinidae. The Siluroidei, however, which were all Bagridae, had much lower excess internal pressures than the other Cyprinifonnes.
Effect of Dissolved Oxygen Concentrations On the Toxicity of Several Poisons to Rainbow Trout (Salmo Gairdnerii Richardson)
Authors: Lloyd R. 
Published: April 2021

ABSTRACT
A given reduction in the dissolved oxygen concentration of the water from the air-saturation value to a lower level increases the toxicity to rainbow trout of zinc, lead and copper salts, and of a mixture of monohydric phenols, to about the same extent. The effect of a reduced oxygen concentration on the toxicity of ammonia solutions is greater than that found for the other four poisons ; the extra increase can be accounted for by a theoretical calculation of the difference between the pH value of the bulk of the solution and that at the gill surface. An hypothesis is presented to account for the effect of low oxygen concentrations on the toxicity of poisons to fish. It assumes that a given toxic effect is produced by a specified concentration of poison at the gill surface, and suggests that this concentration is governed not only by the concentration of poison in the bulk of the solution but also by the velocity of respiratory flow.
Studies On Salt and Water Balance in Caddis Larvae (Trichoptera)
Authors: Sutcliffe D. W. 
Published: April 2021

ABSTRACT
Limnephilus affinis larvae tolerate external salt concentrations up to at least 410 mM./l. NaCl (about 75 % sea water) and survive for short periods in 470 mM./l. NaCl (about 85 % sea water). The body wall is highly permeable to water, but relatively impermeable to sodium and chloride. Most of the sodium and chloride uptake from salt water occurs via the mouth. The sodium and chloride levels in the haemolymph are powerfully regulated. Both are maintained strongly hypotonic against large external concentration gradients. The Malpighian tubule-rectal system is very sensitive to changes in the haemo-lymph chloride level. The chloride concentration in the rectal fluid can be at least three times greater than the concentration in the haemolymph, and slightly greater than the concentration in the external medium. The rectal fluid is hyper-osmotic to the haemolymph and to the medium at high external salt concentrations. At external concentrations greater than about 200 mM./l. NaCl, water balance is maintained by regulating the haemolymph roughly iso-osmotic with the medium. This is partly achieved by increasing the non-electrolyte fraction in the haemolymph. A small quantity of osmotically free water is available to replace any osmotic loss. This can be obtained by drinking salt water and producing a concentrated solution of salts in the rectum.
Colonial Responses of Hydroid Polyps
Authors: Josephson Robert K. 
Published: April 2021

ABSTRACT
Conduction of excitation in response to local mechanical or electrical stimulation has been studied in various hydroid species. There are systems in the coenosarc of the stems and stolons of all species which conduct excitation at rates of from 1 to 3·5 cm./sec. Two physiological types of conducting systems have been found. Through-conducting systems, showing: all-or-none response, sharp threshold, reproducibility. Local systems, showing : spread of response dependent upon stimulus strength, no sharp threshold, responses which decline with increasing distance from the stimulated point, variability. Colonial co-ordination is better developed in those species whose colonies are structurally better developed. It is effected in most species by either (a) or (b). Both types are present together in Hydractinia echinata.
Two Phases of Ageing in Drosophila Subobscura
Authors: Clarke Jean M. , Smith J. Maynard 
Published: April 2021

ABSTRACT
Male and female D. subobscura were kept for varying periods at low temperatures (3−20°C.) and then transferred to a higher temperature (26−30°C.) and kept there until they died. It was found that during the early part of the life span, over the range 15·30°C., every day spent at a low temperature reduced the expectation of life at a higher temperature by approximately i day. Later, when the expectation of life at the higher temperature had fallen to about half its initial value, little further change in this expectation occurred with increasing age at a lower temperature. It is concluded that the life span can be divided into two phases, (i) an irreversible ‘ageing’ process whose rate is approximately independent of temperature from 15 to 30°C., but which is slower at 3°C., and (ii) a ‘dying’ process which is initiated when ageing has proceeded to a stage at which the individual is no longer capable of maintaining a steady state at the temperature at which it is living, although the same individual would be capable of maintaining a steady state at some lower temperature. The rate of the dying process is highly dependent on temperature, and it can be reversed in flies transferred to lower temperatures.
Receptor Potentials Recorded from Sensilla Basiconica on the Antenna of the Silkworm Larvae, Bombyx Mori
Authors: Morita H. , Yamashita S. 
Published: April 2021

ABSTRACT
Several authors have reported on electrical activities of antennae of insects in response to various olfactory stimuli (Boistel, 1953; Roys, 1954; Boistel, Lecomte & Corabœuf, 1956; Schneider & Hecker, 1956; Schneider, 1957). Dethier (1941) studied the sensilla of the antenna of lepidoptera larvae, and assumed that the ‘large’ sensilla basiconica were olfactory organs.
One of the authors (Morita, 1959) recorded slow potentials directly related to occurrence of impulses (i.e. receptor potentials) from the side wall of the contact chemosensory hair on the labellum of the blow-fly, Calliphora vomitoria. The ‘large’ sensilla basiconica on the antennae of lepidoptera larvae are far smaller than the labellar chemosensory hair, but not so small as to prevent application of the method available for the labellar hair. In the present study, using this method, electrical activities of the sensillum basiconicum of the silkworm larva were qualitatively analysed.