bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effects of High Temperatures on Roach (Rutilus Rutilus)
Authors: Cocking Anthony W. 
Published: April 2021

ABSTRACT
The temperature at which 50 % of a sample of roach (Rutilus rutilus) die within a week cannot be raised above 33-5° C. by raising the acclimatization temperature. The roach is about as eurythermal as the yellow perch (Perea flavescens). The mean asphyxial concentration of oxygen at 30 and 32° C. is approximately o-8 mg./l. Median survival time at any lethal temperature increases with increase in acclimatization temperature; survival time for any acclimatization temperature decreases as test temperature increases; the temperature at which 50 % of a sample die within a week rises by about i° C. for each 30 C. rise in acclimatization temperature. The behaviour, on transfer to higher temperatures, depends on the acclimatization temperature and the size of the jump in temperature and can be divided into five characteristic stages. Dying fish develop a black pattern ; myotomie swimming muscles die first and opercular muscles last. The heart was still beating when the fish were opened but the gall bladder was abnormal.
Two Components from the Compound eye of the Crayfish*
Authors: Naka K. , Kuwabara M. 
Published: April 2021

ABSTRACT
The aim of the present investigation was to confirm the results obtained in the previous paper with the aid of the microelectrode. It is concluded that the two components, H-I and H-II, originate from different structures in the receptor layer. It is shown that a difference in the steady potential ranging from 10 to 50 mV is maintained across the basement membrane.
Respiratory Reflexes in the Dogfish
Authors: Satchell G. H. 
Published: April 2021

ABSTRACT
Inflation of the pharynx of a dogfish causes an inhibition of respiration manifested as a reduction in rate and amplitude. Tetanic stimulation of the central end of a cut branchial nerve also inhibits respiration. These inhibitory responses differ in their greater regularity and duration from the transient inhibition arising from stimulation elsewhere in the body. Both normal respiration and inflation cause the discharge of receptors whose impulses pass up the vagus nerve. The pattern of firing of these receptors during an inflation corresponds to the pattern, of inhibition. Brief inflations are more effective in securing inhibition if they arrive at a time when the receptors are not being caused to fire by a normal inspiration. Cutting the branchial branches of the IXth and Xth nerves eliminates the pause between successive respirations and increases the respiratory rate. These pauses can be made to reappear by periodically stimulating the central end of a cut branchial nerve. Section of the brain between the medulla and the mesencephalon increases the sensitivity to inflation. Inhibitory afferents run in all branchial branches of the IXth and Xth nerves and in the pre-spiracular branch of the VIIth nerve. It is suggested that in its response to vagotomy the dogfish resembles a medullary mammal.
The Nerves and Muscles of Medusae
Authors: Horridge G. A. 
Published: April 2021

ABSTRACT
Features of the rhythm of isolated ganglia of Aurelia are the high variability of he intervals between beats and their negative first-order serial correlation coefficient. A regular rapid rhythm or a cyclical rhythm is a consequence of stimulation. The effect of stimulation of the primary (diffuse) nerve net is usually a transient acceleration of the rhythm. A rapid, uniform rhythm is usually reset at a similar frequency by an artificially induced beat; a normal rhythm usually shows a slight pause, which is accentuated if several antidromic impulses are initiated. The pause which follows forced beats, the negative serial correlation coefficient and the time course of the return to normal after stimulation indicate a selfregulating mechanism within the ganglion. Stimulation of the ganglion with direct current can stop or accelerate the rhythm but throws no light on the possible mechanism. When the ganglion is inverted the rhythm becomes slower and more variable. Tryptamine accelerates the rhythm. The minimum effective concentration in the bathing sea water was 10-6 g./ml. Acetylcholine, adrenaline, curare, ephedrine, histamine, 5-hydroxy-tryptamine and physostigmine have no effect. The theoretical relation between the rhythm of one ganglion and of eight connected ganglia shows that the apparent redundancy of ganglia gives a more regular rhythm.
The Hydraulic Mechanism of the Spider Leg
Authors: Parry D. A. , Brown R. H. J. 
Published: April 2021

ABSTRACT
The blood pressure inside the leg of the house spider Tegenaria atrica has been measured. Maintained pressures of about 5 cm. Hg and transient pressures of up to 40 cm. Hg have been found. The relation between the blood pressure in the leg and the extension torque at the hinge joints has been established. Considerable torques can be developed at the hinge joints during extension, for example, when accelerating a mass fixed to the leg. The transient pressures found to arise in the leg are adequate to account for these torques. The hydraulic mechanism is discussed. The available evidence suggests that the pressure found in the legs occurs also in the prosoma but not in the abdomen, in which case the maintained pressure must be due to the heart. This, however, requires further investigation
The Cuticular Pattern in An Insect, Rhodnius Prolixus Stål
Authors: Locke M. 
Published: April 2021

ABSTRACT
The cuticle on the abdominal tergites of Rhodnius larvae has a uniform pattern of stellate pleats. In the adult this pattern is replaced by an oriented one of transverse ridges resembling greatly elongated pleats. Neither pattern results from the disposition of cells each with the potentiality for forming only part of it. The simplicity of the patterns suggests some simple mechanical cause operating over a large area. The effect upon the adult of altering the orientation and relative position of pieces of larval integument has been used to study the mechanism of orientation of the pattern. The orientation of the adult pattern is mediated through the epithelium, since rotation of the larval integument causes corresponding disturbances in the adult pattern. The epithelium has a capacity for maintaining transverse continuity within similar levels in the axis. There is an axial gradient within each segment, the anterior showing greatest facility in maintaining continuity. Pieces of transplanted integument unable to restore their continuity with the whole animal show a concentric pattern of ridges, as if the capacity for continuity had been satisfied by each level joining up with itself. Such isolated pieces of integument moult but fail to grow normally, suggesting that continuity in the axial gradient of the whole animal is necessary for the quantitative control of growth. Pieces of integument from different axial levels within a segment when juxtaposed influence the direction of displacement of the pattern according to their level. A transplant from the anterior stimulates the host ridges to maintain continuity posterior to it, and conversely.
Functional Evidence for Neurone Fields Representing the Individual Arms Within the Central Nervous System of Octopus
Authors: Wells M. J. 
Published: April 2021

ABSTRACT
Octopuses blinded by section of the optic nerves were trained by means of 5-10 V. a.c. shocks to reject objects that they would otherwise take. With trials at 3, 5, or 20 min. intervals, in which the test object was always presented to the same arm, animals learned within four or five trials, thereafter rejecting the test object whenever it was presented. When, after a succession of such negative responses, the object was presented to another arm on the other side of the octopus, the result depended upon the rate of training before the change. Thus the object was taken in the trial immediately following the arm change in nineteen out of twenty-six sets of tests with trials at 3 or 5 min. intervals, but in only two out of twelve sets with trials at 20 min. intervals; further experiments in which changes were made between arms on the same side produced similar results. These results are interpreted as showing that changes occurring as a result of experience directly affecting one arm take a period of several hours to spread and become effective in determining the reactions of the rest. This in turn implies the existence of functionally independent neurone fields representing the individual arms, and is discussed in relation to what is already known about the organization of the tactile system of the octopus.
Visual Scanning in the Desert Locust Schistocerca Gregaria Forskål
Authors: Wallace G. K. 
Published: April 2021

ABSTRACT
This paper describes a lateral swaying movement performed by desert locust nymphs. This movement is called ‘peering’. The angle through which the body moves is influenced by the position of objects in the visual field, showing that the movement is related to vision. When given a choice of two objects at different distances the nymphs show a preference for the nearer one. The estimation of the relative distances of the two objects is not achieved by a binocular method nor is it based on the angle subtended by the objects. An experiment is described in which an object is moved while the insect is peering. If the object is moved in the opposite direction to the insect’s motion the insect jumps short of the object. This seems to support the hypothesis that one of the functions of peering is to estimate distance by the extent of the movement over the retina of an object’s image. This method of distance estimation is discussed with relation to the binocular method. It is suggested that in some cases the peering observed may represent a preliminary scanning of the visual field and may provide information about the finer details of the field.
Pigmentation of An Ostracod,Heterocypris Incongruens
Authors: Green J. 
Published: April 2021

ABSTRACTHeterocypris incongruens contains at least three different types of pigment: carotenoids, a pteridine, and a bilin. Haemoglobin and other haem pigments appear to be lacking in this species. Astaxanthin and β-carotene are the only carotenoids found, even when the ostracod is feeding on algae containing abundant xanthophylls of various types. A yellow pteridine, which rapidly decolorizes after extraction, is widespread in the body of the ostracod, but not in its eggs. It is suggested that this substance may play a part in the intermediate metabolism of the ostracod when in anaerobic conditions. Heterocypris can live and reproduce in anaerobic conditions for at least 2 weeks. Biladiene pigments accumulate in the gut wall when the ostracod feeds on blue-green algae. These pigments can be made to disappear from the gut wall by restricting the diet to green algae, then made to reappear when a blue-green alga is given as food.
The Role of the Epidermal Cells in the ‘Migration’ of Tracheoles in Rhodnius Prolixus (Hemiptera)
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
During the moulting process the tracheal system grows by the extension of new tracheae and tracheoles from the existing tubes. Outgrowths are produced by the active movements of the formative cells of the tracheal epithelium; these give out filiform ‘amoeboid’ processes which move into those regions most deficient in oxygen (Wigglesworth, 1954).
The Jumping Mechanism of Salticid Spiders
Authors: Parry D. A. , Brown R. H. J. 
Published: April 2021

ABSTRACT
Photographs of the jumping spider Sitticus pubescens (Salticidae) show that the jump is almost entirely due to the sudden straightening of the fourth pair of legs. Multiple-image photographs show the importance of a silk drag-line in controlling the jump. The torques at the leg joints have been estimated. Extension torques occur at the two hinge joints although these lack extensor muscles. The erection of leg spines at the moment of the jump provides direct evidence that hydraulic forces are involved in the jump. This view is supported by estimates of the pressures involved, which fall within a factor of about two of those previously measured in the legs of the spider Tegenaria.
Studies on the Metabolism of Locust Fat Body
Authors: Clements A. N. 
Published: April 2021

ABSTRACT
The successive accumulation and depletion of reserves in the fat body of insects shows that it is an important storage organ, but it seems possible that it is also an organ of intermediary metabolism, degrading some substances and elaborating others for use by other tissues. A study was made in vitro of the incorporation of certain metabolites, glycine, leucine, acetate and glucose, labelled with carbon-14, into the fat body of the desert locust, Schistocerca gregaria Forskal. This showed something of the degradation and synthesis occurring in locust fat body and also suggested that the tricarboxylic acid cycle functioned normally, contrary to an earlier report (Hearfield & Kilby, 1958). The results obtained from these studies on the incorporation of labelled metabolites and on the respiration of locust fat body are presented here.
The Mechanism of Gill Ventilation in the Dogfish and Skate
Authors: Hughes G. M. 
Published: April 2021

ABSTRACT
The respiratory movements of the dogfish, ScyUorhinus (Scyllium) canicula (L.), and the ’skate’, Raia clavata L. (thornback ray), have been studied by the use of cinematographic and mechanotransducer recording methods. Simultaneous determinations of the time-course of pressure changes in the oro-branchial and parabranchial cavities were also made by means of Hansen condenser manometers. In both species movements of the mouth precede those of the spiracular valve and of the branchial region. Adduction and abduction of the branchial region spreads serially from the first to last gill slit in the dogfish, but movements of the individual gill arches are more nearly synchronous in the skate. Opening of the flap valves formed by extensions of the inter-branchial septa are synchronous in both species. Water entering one side of the mouth leaves by the three posterior gill slits of the same side. Water entering the spiracle leaves through the anterior slits of the same side. This separation of flow is less marked in the skate. The pressure curves recorded in all parts of the system have both positive and negative phases with respect to the external medium. The positive phase, associated with closing of the mouth and spiracle, is larger in the oro-branchial than in the parabranchial cavities and vice versa. The time-course of the pressure changes indicates that the flow across the gills is maintained by the action of a pressure pump in front and a suction pump behind. The suction pump plays a more important role than the pressure pump in the skate and its contribution to the flow across the gills is by no means negligible in the dogfish. The differential pressure curves suggest that the flow across the gills is continuous except in the dogfish for a brief period when the gradient is reversed. The absence of this reversal in the skate suggests that the external gill slit openings are controlled by an active mechanism. This is probably an adaptation to bottom-living habit. All these observations relate to animals which are stationary with respect to the water. During swimming at a reasonable speed leopard sharks (Triakis semifasciata) have been observed to make few or no respiratory movements, although they immediately ventilate actively on coming to rest at the bottom of the aquarium.
Sodium Regulation in the Crayfish Astacus Fluviatilis
Authors: Bryan G. W. 
Published: April 2021

ABSTRACT
In external sodium concentrations of up to 100 mM./l. the blood sodium concentration of Astacus is only slightly increased. As the external level approaches or exceeds the normal blood sodium concentration of 200 mM./l. so the increase becomes more marked. Similarly, there is an increase in urine sodium concentration. This net gain of sodium is accompanied by a considerable rise in sodium outflux as shown by 22Na. At external concentrations exceeding 300 mM./l., blood and urine concentrations rise to a similar level and active sodium movements appear to cease. With increased blood sodium concentration the level in the muscles rises also. This relationship is not one of simple proportion and at high concentrations there is relatively more sodium in the muscles. In artificial tap water animals with a high blood concentration lose sodium until the normal level is regained. This net loss is due to influx being much lower and outflux much higher than normal. Of the outflux, up to 70% is initially due to renal losses and losses over the body surface are higher than normal due to the excess sodium in the blood. From the results given in this and previous papers the way in which sodium balance may be achieved under normal conditions is discussed.
The Effect of Perturbations in the Environmental Cycle of the Diurnal Rhythm of Activity of Periplaneta Americana L
Authors: Harker Janet E. 
Published: April 2021

ABSTRACT
The locomotor activity rhythm of Periplaneta americana in alternating light and darkness is described as consisting of six stages. The effect on the suboesophageal ganglion neurosecretory cycle of a change from light to darkness at each stage of the locomotor rhythm is described, and three stages in the neurosecretory cycle are recognized. The effect on an established locomotor activity rhythm of a change to darkness at various times of day is described in terms of the immediate reaction of the animal and of the subsequent phase relations of the rhythm. The phases of the activity rhythm are not reset if the environmental change occurs during the active period. The final positioning of the phases, when the onset of darkness occurs during the non-secretory phase of the neurosecretory cycle, is dependent upon the subsequent light conditions; transient activity peaks may appear before the stable position is reached. The dependence of the neurosecretory cells on some other centre for the provision of some secretory substance, or precursor, is discussed.
Heat Loss and the Body Temperatures of Flying Insects
Authors: Church Norman Stanley 
Published: April 2021

ABSTRACT
Comparative measurements of body temperatures and water loss in Schisto-cerca gregaria showed that evaporation dissipates relatively little of the heat generated by the wing muscles during flight. In perfectly dry air at 30°C., evaporation reduces the temperature excess of the pterothorax by less than 10%, or about 0·5°C. Even at 40°C., which is the highest temperature that will permit continuing flight, the reduction is only about 20%, or 1·2°C., in dry air. A flying locust has no special mechanism, except cessation of flight, to protect it from overheating. Breathing is not markedly increased at high temperatures, nor is the rate of heat production reduced. Very little heat is dissipated from the pterothorax by evaporation through the cuticle. The cuticle becomes permeable enough to allow substantial cooling only at temperatures well above the highest that permit flight. Temperature measurements in Triphaena pronuba and Bombus lapidarius supported the idea that evaporative cooling during flight is not much more important in other well-waterproofed insects. Large changes in the humidity produced changes of less than 1°C. in the temperature excess, even at the highest air temperatures at which the insects could fly. The reactions of the insects to moist and dry air are adapted to the conservation of their water rather than to rapid cooling.
Heat Loss and the Body Temperatures of Flying Insects
Authors: Church Norman Stanley 
Published: April 2021

ABSTRACT
The natural internal temperature gradients during flight were reproduced in various medium and large insects by mounting freshly killed specimens in a wind tunnel and heating them with a high-frequency electric current. The heat flow from the flight muscles to other parts of the body and from the body were investigated. Comparison of dead and living insects showed that most of the heat transfer within the body is by conduction; circulation of the haemolymph during flight contributes little to the heat flow. The temperature excess is high throughout the pterothorax in a large insect; where there are no subcutaneous air sacs it is only about 10% less at the surface of the pterothorax than at the centre. Only about 5-15% of the heat generated in the flight muscles is conducted to the prothorax, head, abdomen and appendages, which remain near the temperature of the air. Usually not more than 10-15% of the heat escapes from the pterothorax by long-wave radiation in a large insect flying under a clear sky. Smaller insects lose relatively more of their heat by radiation. Radiation increases with the insect’s temperature but it is never sufficient to give much protection against overheating. Ordinarily 60-80% of the heat is dissipated from the surface of the pterothorax by convection. In convection from a naked insect the relationships between heat loss, the surface temperature excess, size, and wind speed are nearly the same as in convection from a smooth cylinder or sphere, if allowance is made for turbulence in the air flow over the insect. In dragonflies and denuded bees and moths heated in proportion to their pterothoracic volumes in a constant wind, the temperature excess was proportional to the 1·3-1·5 power of the average diameter of the pterothorax. The coats of hair on bumble-bees, hawk moths, and noctuid moths are excellent insulators against convective heat loss. At normal flying speeds they increase the temperature excess by 50-100% or more--in a large hawk moth probably by at least 8 or 9° C. The insulating value of a coat depends mostly on its density and on the size of the insect, and less on the length of the hair. In dragonflies the pterothorax is insulated nearly as effectively by the subcutaneous air sacs.
Nervous Control of Movement in Annelids
Authors: Wilson Donald Melvin 
Published: April 2021

ABSTRACTNerve muscle preparations of the segmental nerves and associated muscles have been made using a nereid polychaete, Neanthes brandti (Malmgren). Two kinds of response, differing in threshold and latency, were found. The ‘fast’ response is large at the first shock and (at frequencies above 1/sec.) decreases thereafter. The ‘slow’ response is small but facilitates with repetition at frequencies above 10/sec. Facilitation reaches a maximum after 3 or 4 shocks. Isolated parapodia show several distinct reflex movements to mechanical and chemical stimuli. These must involve motor neurons in the parapodial ganglion. Stimulation of the segmental nerves of the leech, Hirudo, evokes facilitating muscle potentials resembling in most details those of the ‘slow’system in Neanthes. The ‘fast’ and ‘slow’ responses are discussed in comparison with other invertebrate systems, especially those of arthropods. The ‘slow’ responses in annelids show less facilitation. The ‘fast’ responses of polychaetes fatigue quickly and are probably useful only in ‘startle’ responses.
Nervous Control of Movement in Cephalopods
Authors: Wilson Donald Melvin 
Published: April 2021

ABSTRACTNerve muscle preparations have been made of the mantle and stellar nerves of octopuses and squids. Two motor innervation systems have been found in each. Both have been observed as unit preparations. The possibility of double innervation of the same muscle cells exists but has not been directly checked. The fast innervations produce electrical responses which are maximal to the first stimulus and which have little or no absolute refractory period. They appear to be local rather than spike potentials. Fatigue is very rapid. The mechanical response sums in Octopus, but not in Loligo. The slow innervations produce electrical and mechanical responses which facilitate with repetition. The fast system of Loligo does likewise after fatigue to a low level of response. No evidence was found for a functional nerve net in the mantle. Organizational features of the stellate ganglion have been identified physiologically in Octopus. The ganglion acts both as an integrating motor centre and as a reflex centre.