bluuebunny/crossref_metadata_2025_split huggingface dataset:
Blood Gases of the Tench (Tinca Tinca) in Well Aerated and Oxygen-Deficient Waters
Authors: Eddy F. B. 
Published: April 2021

ABSTRACT
The respiration of tench at 13 °C was investigated, particular attention being given to the role of the blood in uptake and transport of oxygen. In well aerated water the mean value for arterial blood was 36 mmHg, for 3·3 mmHg and for pH 8·16; the respective venous values were 7 mmHg, 5 mmHg and 8·08. Arterial blood averaged about 75 % and venous blood about 40 % oxygen saturation. The mean value for oxygen uptake was 0·5 ml/min/kg and for ventilation volume 132/ml/min/kg. The oxygen tension and the percentage saturation of the blood determined in vivo are discussed in terms of the oxygen dissociation curve determined in vitro. When the environmental was decreased, tench responded by increasing breathing rate and ventilation volume. Arterial and decreased but arterial pH tended to remain steady. There was also a significant increase in blood lactate. That tench can withstand severe hypoxic conditions is attributed to blood of high oxygen affinity and the ability to maintain a favourable acid-base status in the blood for oxygen transport. Respiration in tench is compared with that in other fish species.
Changes in Critical Temperature During Nymphal and Adult Development in the Rabbit Tick, Haemaphysalis Leporispalustris (Acari: Ixodides: Ixodidae)
Authors: Davis Minh-Tam Bui 
Published: April 2021

ABSTRACT
During the developmental period from nymphal to adult engorgement of the rabbit tick, Haemaphysalis leporispalustris, critical temperature changed with developmental stage and nutritional state, but was similar in the two sexes. Critical temperature was low in engorged nymphs one day after drop-off (in the range of 36–40 °C), increased during the following 15 days (46–47 °C), slightly decreased just after ecdysis (42–43 °C), remained constant in unfed females for the next 2 months (42–43 °C) and then decreased again during engorgement of adult females (from 42–43 to 37–38 °C then to 35–36 °C). The rates of water loss also changed with the developmental period. The hypothesis that evaporative water loss might initiate the rapid engorgement phase is supported, although not confirmed, by a close correspondence between the host body temperature and the critical temperature of the tick just prior to the rapid engorgement phase.
The Water Balance of a Serpulid Polychaete,Mercierella Enigmatica(Fauvel)
Authors: Skaer Helen Le B. 
Published: April 2021

ABSTRACTThe electrical activity of the two types of longitudinal muscles of an osmoconforming polychaete worm, Mercierella enigmatica, have been studied in media of widely varying osmotic and ionic composition. Activity persists practically unaltered in both types of muscle cell. The possible effects of osmotically induced changes in cell volume on the ionic gradients across the cell membranes are considered. It is concluded that the normal gradients are unlikely to be maintained as a result of such changes. The involvement of ion pumps in the maintenance of the normal gradients across the muscle cell membranes has been studied using specific and metabolic poisons. It is evident that the persistence of electrical activity in media of altered ionic content does not depend on the sodium-potassium exchange pump. The ionic basis of the overshoot of action potentials recorded from cells of the small resting potential type has been studied. It is concluded that calcium ions but not sodium ions are responsible for the inward current although there is a component of the inward current carried by some other as yet unidentified ion. Alterations in the external concentrations of chloride ions are found to alter both the height of the overshoot and the length of the action potential. Profound alterations in the overshoot height are produced only when the normal ratio of calcium to chloride concentration in the external medium is altered. Possible mechanisms to explain these effects are discussed. It is suggested that the stability of the action potential in the muscle cells of M. enigmatica, despite large fluctuations in the salinity of the external medium, depends on the constancy of the ratios between the concentrations of the ions in the fluids bathing the cells and not on the absolute concentrations of the ions.
Excitatory and Inhibitory Control of Inherent Contractions in the Sea Anemone Calliactis Parasitica
Authors: McFarlane I. D. 
Published: April 2021

ABSTRACT
Bursts of nerve-net activity are always followed by a contraction cycle involving parietal and circular muscle contractions in isolated preparations of Calliactis parasitica. Both muscle groups can, however, also contract in the absence of nerve-net activity. These contractions, termed inherent, seem to follow periods of reduced activity in the endodermal slow conduction system (SS2). Electrical stimulation of the SS2 inhibits inherent contractions of parietal and circular muscle preparations. Electrical stimulation of the nerve net excites parietal muscles but seems to have both excitatory and inhibitory effects on circular muscles. A model for control of parietal and circular muscle contractions proposes that both the nerve net and the SS2 are responsible for directing the inherent muscular activity into the observed contraction cycle. It is suggested that when the action of these antagonistic muscles is strongly opposed the SS2 pulse frequency rises, resulting in inhibition of further muscular activity.
The Permeability to Water of the Cuticle of the Larva of Opifex Fuscus (Hutton) (Diptera, Culicidae)
Authors: Nicolson Susan W. , Leader John P. 
Published: April 2021

ABSTRACT
Fourth-instar larvae of Opifex fuscus were found to have a mean body weight of 7·61 mg, a water content of 85·2%, and a mean cuticular surface area of 29·3 mm2. Larvae ligatured at neck and anus were found to lose 1 % of the body weight per hour when immersed in sea water. The osmotic permeability coefficient of the cuticle was calculated from these data to be 2·4 × 10− 2 cm. h− 1. Measurement of the diffusional permeability coefficient (Pd) by means of tritiated water and Deuterium oxide gave a value for this parameter of 4·8 × 10− 3 cm.h− 1. The diffusional permeability of the cuticle of Opifex fuscus is thus less than that of typical freshwater insects, as predicted by Shaw & Stobbart.
The Passive Permeability of Insect Malpighian Tubules to Organic Solutes
Authors: Maddrell S. H. P. , Gardiner B. O. C. 
Published: April 2021

ABSTRACT
The permeability of Malpighian tubules of five insect species to a range of organic solutes has been measured by both in vitro and in vivo techniques. Nearly all the substances tested were found, in in vitro experiments, to penetrate the walls of Malpighian tubules in a manner which, on several criteria, was judged to be passive. The walls of Malpighian tubules are more permeable to small molecules than to large ones; but even inulin (MW 5200) penetrates fast enough to reach concentrations which, in tubules secreting fluid slowly, can be as high in the secreted fluid as 50 % of its concentration in the bathing fluid. Inulin injected into Schistocerca and L-fucose injected into Rhodnius appeared in the excreta at rates which could be accurately predicted from the in vitro behaviour of Malpighian tubules of these insects. Taken with the fact that the cuticular lining of the rectum of insects is thought to be not very permeable, the high permeability of insect Malpighian tubules means that the reabsorption of useful compounds of the order of size of disaccharides must to some extent occur before excretory material reaches the rectum. It is suggested that the circulation of lipids and hormones in the form of complexes with proteins is a device to prevent their rapid loss through the excretory system.
The Electrophysiology of Photoreceptors in the Nudibranch Mollusc, Tritonia Diomedia
Authors: Chase Ronald 
Published: April 2021

ABSTRACT
Tritonia has two eyes, each lying beneath the integument at the base of the rhinophore. Three cell types are present in the eye: large photoreceptors with nuclei up to 50 μ m in diameter, pigment cells, and epithelial cells. A count of nuclei revealed a total of five receptors in each eye. All receptors produced depolarizing generator potentials in the presence of light, regardless of intensity within the responsive range. Responses usually consisted of a fast early depolarization followed by a more slowly rising component. Spikes were uncommon in receptor somata. When present, spikes were superimposed on the slower phase of the response and measured no more than 12 mV. Depolarization was maintained at a steady level when illumination was sustained. The receptors are coupled electrotonically, and synaptic inhibition was evident in a few cells. The functional consequences of these interactions are considered to be minimal. Morphologically, the eye of Tritonia is very similar to that of the nudibranch, Hemissenda. But there are significant differences in the electrophysiology of the two eyes, particularly with respect to cell interactions. Although the maximum recorded sensitivity was about five orders of magnitude less than that considered to be necessary for the detection of sunlight in Tritonia’s natural habitat, a visual role in the regulation of periodic behavioural patterns cannot be definitely excluded. The eye may also function in the location or identification of luminescent pennatulids, the major source of food for Tritonia.
Co-Ordination of two Kinds of Flight Activity in an Aphid
Authors: Kennedy J. S. , Ludlow A. R. 
Published: April 2021

ABSTRACT
The interaction between ‘migratory flight’, defined as flight oriented vertically and horizontally towards a large overhead light source, and ‘targeted flight’ oriented towards a yellow leaf-like object seen to one side against a dark background, has been analysed in Aphis fabae in a laboratory flight chamber. Landings were prevented by regulating a down-current of air so as to balance the flier’s rate of climb and by momentary withdrawal of the target when the flier came close. The longer an aphid had flown before the target appeared the more persistently it homed-in on the target and the more its rate of climb was depressed by the presence of the target. This ‘priming’ of targeted flight during migratory flight could be counteracted by suitably repeated bouts of presentation of the target. Such a treatment tended rather to prime migratory flight responses to the target stimulus, that is avoidance of the target and increase in the rate of climb. The visual stimulus from the target had both excitatory and inhibitory effects on the rate of climb, mixed in varying proportions. Antecedent events in the behavioural chain governed the magnitude and relative timing of these effects. The excitatory effect usually followed an inhibitory one but it could occur first or even alone, and was thus a separate effect not comparable with post-inhibitory rebound.
Acoustic Stimulation of the Ear of the Goldfish (Carassius Auratus)
Authors: Fay Richard R. , Popper Arthur N. 
Published: April 2021

ABSTRACT
Microphonic potentials were recorded from the ears of the goldfish during acoustic stimulation in a situation where sound pressure and particle displacement could be varied. Microphonic potentials from fishes with the swim bladder intact were proportional to sound pressure. After removal of the swim bladder, sound pressure sensitivity declined by 20-35 dB and the response was generated in proportion to particle displacement. The ear’s sensitivity to direct vibration of the head increases at between −3 and −6 dB/octave between 70 and 1500 Hz and is not affected by the removal of the swim bladder. It is concluded that the peripheral auditory system of the goldfish may function as a pressure detector or as a displacement detector, depending upon the impedance of the applied signal.
The George Bidder Lecture 1973: Brains and Worlds: the Cerebral Cosmologies
Authors: Young J. Z. 
Published: April 2021

ABSTRACT
I hope it may not be too ambitious to spend our time asking again the old question ‘What is the world really like?’ I shall bring you a little evidence of how Dr George Bidder himself regarded this question, and I like to think that with his strong and freely ranging mind he would have approved our attempt to tackle even these very difficult matters.
Increased RBC Count and Pulmonary Respiration in Cold-Adapted Frogs
Authors: Krishnamoorthy R. V. , Shakunthala N. 
Published: April 2021

ABSTRACT
Haematological and respiratory parameters (including RBC count, CO2 content and percentage oxygen saturation) were studied in cold-acclimated (12 ± 1 °C) and normal frogs (23 ± 2 °C). Seasonal variation in RBC count was found, the count being higher in January than in September. Females showed higher counts than males. Cold-acclimation resulted in the elevation of counts in all seasons and in both sexes, and was accompanied by a rise in haemoglobin content. Cold-acclimated frogs retained a higher oxygen saturation in the truncus arteriosus than in the cutaneous vein, the carbon dioxide content of the truncus being also reduced in acclimated frogs. The O2/CO2 ratios were thus higher in the truncus than in the cutaneous vein. Cold-acclimated frogs released more 14CO2 through the lungs. It is suggested that a change in the mode of respiration occurs when the frogs are acclimated to cold.
Interrelationships Between Water and Metabolism in Artemia Salina Cysts: Hydration-Dehydration from the Liquid and Vapour Phases
Authors: Clegg James S. 
Published: April 2021

ABSTRACT
Average weights of individual CaSO4-dried cysts (3·64 μg), shells (0·74 μg) and embryos (2·90 μg) of the brine shrimp, Artemia salina, were determined.’Residual water’ contents of these preparations were estimated to be 1·58 (cysts), 0·79 (shells), and 1·78 (embryos) in units of g H2O/100 g dried weight. Cysts hydrated to a similar degree in the liquid or vapour phase of NaCl solutions at o °C. Sorption isotherms revealed marked hysteresis for isolated shells, but not for entire cysts or the embryonic component. Adsorption data were plotted according to the Brunauer-Emmett-Teller equation and BET parameters were calculated and discussed. Cyst populations incubated at relative vapour pressures of water of 0·96 and above underwent a loss of dried weight, emerged in the hygrostats, and showed a decrease in viability. The foregoing did not occur at relative vapour pressures of 0·925 and below. The water content required for initiation of these events was estimated to be somewhere in the range of 46 to 72 g H2O/100 g dried cysts.
Eco-Physiological Studies of an Intertidal Crustacean, Pollicipes Polymerus (Cirripedia, Lepadomorpha): Aquatic and Aerial Respiration
Authors: Petersen J. A. , Fyhn H. J. , Johansen K. 
Published: April 2021

ABSTRACT
Gas exchange in water and in air of the intertidal cirriped Pollicipes polymerus has been studied by combined field and laboratory experiments. Haemolymph gas tensions and pH are correlated with the tidal cycle in the field. Air exposure is accompanied by increasing oxygen and carbon dioxide tensions, and by decreasing haemolymph pH. During resubmersion the respiratory parameters are restored to values typical of the submerged state. There is no accumulation of lactic acid during air exposure. The oxygen uptake of Pollicipes is higher for air exposed than for submerged animals at each tested temperature. In air exposed animals the oxygen uptake shows a decreasing Q10 with increasing temperature between 2 and 27°C. Pollicipes exhibits oxygen conformity under varying ambient oxygen tensions and no oxygen debt is found after exposure to hypoxic water. The peduncle cuticle is permeable to oxygen and cutaneous respiration at this level may contribute significantly to the overall oxygen uptake. Pollicipes is well adapted to respiratory gas exchange both in water and in air making it a successful species in the intertidal community.
The Effect of Metabolic Inhibitors On the Cockroach Nerve-Muscle Synapse
Authors: Rees D. 
Published: April 2021

ABSTRACT
The application of metabolic inhibitors to nerve-muscle synapses on ‘white’ and ‘red’ fibres in the retractor unguis muscles of P. americana and B. giganteus resulted in a dramatic increase in the spontaneous miniature potential discharge and was accompanied by a summation of the miniature potentials to form ‘composite’ potentials. Axon terminals associated with ‘white’ muscle fibres responded faster to metabolic inhibitors than those axon terminals associated with ‘red’ muscle fibres. Correlated ultrastructural and electrophysiological studies inferred that a tentative relationship existed between the miniature potential activities and synaptic vesicle distributions of the nerve-muscle synapses during the phases of metabolic inhibition.
The Possible Involvement of Brain Microtubules in Memory Fixation
Authors: Cronly-Dillon John , Carden David , Birks Carole 
Published: April 2021

ABSTRACT
Goldfish were trained to discriminate between two coloured lights. When colchicine was administered intracranially immediately after training it produced complete retrograde amnesia 2 days later, but the fish displayed considerable retention if instead the injection was given 1·25 h after training. If colchicine was administered 1·25 h before training the fish were able to learn as readily as control fish but then showed retrograde amnesia when tested 2 days later. It is suggested that colchicine may affect memory fixation by interfering with the fast transport of material needed to bring about a structural modification at certain synapses.
The Effect of Haemolymph Osmotic Pressure On the Meal Size of Nymphs of Locusta Migratoria L
Authors: Bernays E. A. , Chapman R. F. 
Published: April 2021

ABSTRACT
Injection of trehalose into the haemolymph of Locusta nymphs reduced the amount of grass eaten in one meal. Greater effects were produced by higher concentrations and most reduction occurred when meals began 20 min after injection.
Sodium chloride, glycine, proline, sorbose, inulin or a mixture of solutes had similar effects.
The similarity of effects is explicable in terms of the increase in haemolymph osmotic pressure.
The increase in the osmotic pressure normally occurring during feeding is not great enough to affect the current meal.
Function of the Anuran Conus Arteriosus
Authors: Morris R. W. 
Published: April 2021

ABSTRACT
The anuran conus arteriosus was studied by direct observation of its structure and function and by observing the effects of artificially induced contraction on the pressure pulse in the arterial arches. The beat of the anuran conus was found to close the outlet to the pulmocutaneous arches. The timing of the beat of the conus in the ventricular cycle is variable; early in the cycle the conus admits less blood to the pulmocutaneous circuit, more blood being admitted when it beats late. The timing of the beat of the conus appears to be adaptively related to beat frequency and to pH of the system. Elementary calculations suggest that these characteristics constitute an important measure of survival value of the anuran conus. The findings of this work are compatible with the theory of selective passage of two streams through the heart, supplementing such passage with additional control of blood volumes entering the pulmocutaneous circuit.
Some Auditory Discrimination Experiments On Marine Fish
Authors: Chapman C. J. , Johnstone A. D. F. 
Published: April 2021

ABSTRACT
The ability of cod, Gadus morhua (L.), and haddock, Melanogrammus aeglefinus (L.), to discriminate changes in sound direction and amplitude was studied using a cardiac conditioning technique. In one experiment it was found that the masking effect of noise transmitted from one sound projector on the ability of the fish to detect a tone (60–380 Hz) transmitted from another projector was reduced by 7 dB when the angle between the projectors was 45° or greater. It was also shown that the fish could be conditioned to a change in the direction of a pulsed tone switched between two projectors. The fish were able to discriminate changes in sound amplitude of 1·3–9·5 dB at frequencies between 50 and 380 Hz. The results are discussed in relation to sound localization in fish.
Nitrogen Metabolism in the American Cockroach: An Examination of Whole Body Ammonium and Other Cations Excreted in Relation to Water Requirements
Authors: Mullins Donald E. 
Published: April 2021

ABSTRACT
The effects of dietary nitrogen levels in relation to ammonotelism, cation excretion and water requirements were examined in the American cockroach, Periplaneta americana (L.). Very little ammonia is released from the respiratory surfaces; rather it appears to be eliminated in the faeces, presumably as ammonium ions. Microflora present in the hindgut may contribute significantly to the production of excreted ammonia under certain dietary conditions. Injections of buffers containing either NH4+, K+ or Na+ resulted in normal (NH4+ and K+), or less than normal (Na+) levels of ammonia excretion. Faeces collected from cockroaches maintained on twelve different diets containing various levels and sources of nitrogen were examined for NH4+, K+, Na+, Ca2+ and Mg2+. Ammonium ions were found to be the major cations contained in the faeces and were excreted in increasing amounts as the dietary nitrogen levels increased. The ad libitum water requirements were closely correlated with dietary nitrogen levels, and subsequently with ammonia excretion. Certain aspects concerning the possible factors involved, and the significance of ammonia excretion, are discussed.
Neuronal Homologies and the Control of Branchial Tuft Movements in Two Species of Tritonia
Authors: Dorsett D. A. 
Published: April 2021

ABSTRACT
Comparative morphological and physiological studies of the branchial tuft retractor system of Tritonia hombergi and T. diomedia show a number of similarities and differences. In both species two homologous neurones in each pedal ganglion produce complete and partial contractions of the ipsilateral pinnae respectively.
Three pleural neurones cause bilateral contractions in T. hombergi: L Pl 6 and R Pl 5 inducing complete, and R Pl 6 partial, withdrawal of the tips. This differs from T. diomedia, where principal control is vested in the pleural giant cells.
The latency of tuft withdrawal declines and the rate of contraction increases with increasing impulse frequency in the retractor neurones, the musculature apparently responding to the second impulse of a series. After due allowance for conduction delays, only a small interval remains unaccounted for. Until electrical activity can be recorded from the musculature, the suggestion of the relay of central excitation through the peripheral plexus must be regarded as uncertain.
Kinetic Characteristics of Glycine Transport by the Isolated Midgut of the Marine Shrimp, Penaeus Marginatus
Authors: Ahearn Gregory A. 
Published: April 2021

ABSTRACT
Mucosal glycine influx occurred via a single carrier-mediated, active transport entry process (Kt= 0·36 mm; Vmax = 0·42 μmoles/g. min) with an absolute Na+ requirement. Glycine transport inhibition by N2 gas, NaCN, NaN3, iodoacetate, 2,4-DNP, and ouabain was more extensive at 0·1 mm than at 1·0 mm glycine, suggesting a greater proportion of energy-dependent transport at lower amino acid concentrations. Aliphatic neutral amino acids and histidine were more potent inhibitors of mucosal glycine influx than were aromatic neutral, and anionic amino acids. Alanine was a fully non-competitive inhibitor of mucosal glycine entry, whereas proline appeared to be a fully competitive inhibitor of luminal glycine transfer. D-Fructose added to the incubation medium restored normal glycine transport in the presence of alanine, indicating that the two amino acids most likely utilized separate, energy-consuming, mucosal transport processes. A tentative model of glycine transport in the penaeid shrimp intestine is presented.