bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long-Term Facilitation in A Swimming Sea Anemone
Authors: Wilson Donald M. 
Published: April 2021

ABSTRACT
The peculiar behaviour of the anemone, Stomphia coccinea (O. F. Müller), in response to certain starfishes was noted by Yentsch & Pierce (1955). More detailed description of the swimming reaction and attempts to identify the stimulating factor involved were made by Sund (1958). The easily measured sequence of events which constitutes the response provides an opportunity to analyse quantitatively integrated behaviour in a coelenterate. This study is an attempt to identify and measure a process which might be considered a type of learning in an animal with simple neural organization. Guessing that the relationship between the starfish Dermasterias and Stomphia might be a predator-prey one (although no evidence favours this assumption) it seemed likely that encounters which resulted in no harm to the anemone might result in habituation. Experiments have therefore been done to test whether the swimming behaviour of this animal is modified by previous occurrences of the stimulus. It was a surprise to find that the reaction is enhanced by repetition. The results indicate long-lasting changes within the animal which have been called here long-term facilitation. This is a kind of modification of behaviour of the same apparent complexity as habituation but with opposite sign. Facilitation of monosynaptic reflexes lasting minutes or hours has been mentioned by Eccles (1958), but while such relatively simple neural mechanism for modifiability of response has been demonstrated, no comparable type of learning is currently included in several reviews of animal behaviour, though it is recognized that a facilitation process could be the basis of imprinting. In the attacking response of young cephalopods Wells (1958) has demonstrated facilitation without reward.
Nitrogen Excretion in Nymphs of Aeshna Cyanea (Müll.) (Odonata, Anisoptera)
Authors: Staddon B. W. 
Published: April 2021

ABSTRACT
The excretion of ammonia and uric acid has been studied in nymphs of Aeshna cyanea (Odonata, Anisoptera). Ammonia is the main nitrogenous component of the excreta of nymphs during fasting and after feeding on a protein-rich diet. Only a small proportion of the total nitrogen excreted is present as uric acid. Retention of uric acid in the body is at most trivial. When fasting nymphs are fed on a protein-rich diet in the form of egg-white there is a large, temporary increase in the amount of ammonia excreted, but the output of uric acid remains constant. It has been estimated that nymphs excrete a quantity of nitrogen within 24-48 hr. after feeding equivalent in amount to 60% or more of the total nitrogen absorbed during that period.
The Effect of Anaerobic Conditions on Two Heterotrich Ciliate Protozoa From Papyrus Swamps
Authors: Beadle L. C. , Nilsson J. R. 
Published: April 2021

ABSTRACT
That a number of aquatic invertebrate animals can live for long periods in the complete absence of oxygen, and that many are actually called upon to do so in their natural habitat, is a reasonable conclusion to draw from the extensive work on this subject which has been reviewed by von Brand (1946). Since most animal tissues can derive energy from an anaerobic glycolysis, the major problem of adaption to prolonged lack of oxygen would appear to be the removal of (or acclimatization to) the products, mainly fatty acids, of an anaerobic metabolism. Many of the previous experiments were, however, open to criticism in view of the uncertainty that completely anaerobic conditions were attained. It is difficult also to establish beyond doubt that an animal has no access to traces of oxygen in nature, and the methods used for oxygen estimation were not likely to be sensitive to low concentrations in water containing reducing substances.
A Touch-Learning Centre in Octopus
Authors: Wells M. J. 
Published: April 2021

ABSTRACT
Octopuses were trained to reject objects touched, after section of the optic nerves and removal of parts from the supraoesophageal brain mass. Removal of the vertical lobe has effects, described in full elsewhere, that may be broadly described as reducing the efficiency of the learning process—the animals require more trials to attain the same standards of accuracy of response as controls. Additional removal of the basal lobes produces no further decline in learning performance, although such animals show postural defects and cannot make movements that entail integration of the activities of the individual arms. Extension of the lesion to remove the inferior frontal and subfrontal lobes produces animals that cannot be taught to change their reactions towards objects touched, although the movements concerned in taking or rejecting objects by single arms remain unimpaired. The latter are integrated within the axial cords of the arms concerned, and can be demonstrated in isolated arms. Evidence is given that the organizational changes constituting learning are limited to the lateral inferior frontal and subfrontal lobes, and that the median inferior frontal is a distributive region. Animals with only a few tens of thousands of cells left in the lateral inferior frontal/subfrontal system can learn to reject an object repeatedly presented, but rather more tissue must remain before a satisfactory performance is obtained in discrimination experiments.
Experiments on the Selection of Algal Substrates by Polyzoan Larvae
Authors: Ryland J. S. 
Published: April 2021

ABSTRACTMany species of Polyzoa show marked specificity with regard to the substrate on which they occur. Epiphytic forms are often found mainly on one species of alga. Experiments were performed in which a number of algal species were offered to polyzoan larvae as substrates for settlement. The disposition of algae, and the dishes containing them, was such that the layout conformed to a Youden Square design. This not only achieved economy of materials, but ensured a balanced experiment, made possible a statistical analysis of the results, and eliminated any possible effects of extraneous environmental factors. The larvae showed marked substrate preferences when settling. In the littoral forms Alcyonidium hirsutum, A. polyoum and Flustrellidra hispida, the selection of algae accorded closely with their observed natural distributions: in each case highest settlement took place on Fucus serratus. It seems probable that positive selection plays an important role in determining the distribution of these species on the shore. Celleporella hycdina larvae were also selective, but the preferences were less clearly related to the ecological distribution of the adult. Surface texture appears more important than contour as a factor influencing the choice made by larvae between algal substrates, although the physical and/or chemical factors responsible for the observed differences in attractiveness of algae are largely unknown. However, it is evident that the nature of the surface alters with age, and that this influences favourability. The presence of mucus has an adverse effect on settlement. Once the actual substrate has been chosen, the larvae respond to surface contour and, if possible, select a groove or concavity as a site for fixation.
Sodium and Potassium in the Endolymph and Perilymph of the Statocyst and in the Eye of Octopus
Authors: Amoore J. E. , Rodgers Kathleen , Young J. Z. 
Published: April 2021

ABSTRACT
The concentrations of sodium and potassium were measured in 0.1-3.5 μl. samples of the following body-fluids of Octopus vulgaris: perilymph and endolymph from the statocyst, anterior and posterior chamber fluid from the eye and blood. All these fluids had approximately the same sodium concentration as the sea-water, but slightly higher concentrations of potassium. The blood had the highest concentration of potassium, 30 m.-equiv./l., or over twice that in the sea. In the endolymnph the potassium concentration was 20 m.-equiv./l.
Speed and Stamina in Three Fish
Authors: Bainbridge Richard 
Published: April 2021

ABSTRACTMeasurements of the maximum speed sustained during bursts of swimming of up to 20 sec. duration by dace, trout and goldfish of various lengths are reported. The ability to sustain periods of swimming appears to be related differently to length in different species. In the dace it is proportional to L1·09, in the trout and goldfish to L0·65. The dependence of this relationship upon various factors is considered. It is concluded that allometric increase of muscle and the influence of an increasing Reynolds number, possibly combined with other, physiological, factors could adequately account for the variation observed. The precise form of the speed/duration relationship differs in different species. These variations are also probably accountable for by a combination of different muscle percentages and fineness ratios together with other, physiological, factors. The ability to maintain speed diminishes rapidly with increasing time interval in all the species measured. The maintained speed falls from about 10L/sec., maintainable for only 1 sec. of swimming, down to 5L/sec. for 10 sec. and further to a cruising speed of about 4L/sec. by 20 sec. The nature of this time/speed relationship is considered to be determined by the ability of the muscle to utilize stores of raw material and by the rates at which these can be supplied to, and waste products removed from, the muscle. A diagram showing the relationship between velocity of water flow and the maximum distance which various hypothetical fish could traverse in such currents is constructed; and possible applications of this information are briefly considered.
The Physiology of Contractile Vacuoles
Authors: Kitching J. A. , Padfield J. E. , Rogers M. H. 
Published: April 2021

ABSTRACT
The suctorian Discophrya collini (Root) has been subjected to D2O–H2O mixtures containing up to 99·7 % D2O. In 25 % D2O or over there is a rapid but temporary shrinkage of the body. This shrinkage is difficult to estimate owing to the wrinkling of the body surface, but amounts to at least 10% in the undiluted (99.7%) D2O. During the period of temporary shrinkage the contractile vacuole ceases activity. Normal activity is resumed when the normal volume is regained. In concentrations of D2O too low to cause shrinkage there is a temporary fall in the rate of vacuolar output. Return to H2O leads to a brief but often very considerable rise in vacuolar output. It is concluded that D2O penetrates less rapidly than H2O. A difference of at least 10 % in the diffusion constants in the membrane would be required to explain our results. We cannot exclude this as unreasonable from our data, although an explanation based on differences in the equilibrium properties of D2O and H2O might also be invoked.
The Permeability of the Shell of the Egg of Acheta Commodus Walker*
Authors: Browning T. O. , Forrest W. W. 
Published: April 2021

ABSTRACT
The passage of deuterium oxide across the egg membranes of Acheta commodus has been studied. Deuterium oxide enters the egg at times when its weight is constant and leaves the egg at times when its weight is increasing as a result of uptake of water. It is considered unlikely that these findings can be accounted for by simple exchange with hydrogen atoms in the membrance. It is concluded that the shell membrances are permeable to water at all times.
Induction of Diapause in Erioischia Brassicae Bouche (Dipt., Anthomyiidae)
Authors: Hughes R. D. 
Published: April 2021

ABSTRACT
The overwintering resting stage of the cabbage rootfly (Erioischia brassicae) is a facultative diapause in the pupal instar. The induction of the diapause takes place during larval development and appears to be governed by changes in the daylength operating through the host plant. It is suggested that the daylength stimulus is passed on to the insect by way of a change in the composition of its food, and this hypothesis is supported by the finding that a long-day stimulus remains apparent to feeding insects after the host plant has been removed to short-day treatments.
Respiration in the Desert Locust
Authors: Miller P. L. 
Published: April 2021

ABSTRACT
Normal (dorso-ventral) and three auxiliary ventilating mechanisms (neck, prothoracic and abdominal longitudinal) are described in the non-flying Schistocerca gregaria. Neck and prothoracic ventilation together contribute 14% of the maximum volume of air pumped by the insect. Head ganglion receptors must be stimulated for these forms to appear. The metathoracic ganglion may contain a pacemaker controlling the frequency and amplitude of all forms of ventilation. Each head and thoracic ganglion contains carbon-dioxide receptors which modify the activity of the pacemaker. There is no control from the abdomen in the intact insect, or from receptors outside the central nervous system. Oscilloscope recordings from the isolated central nervous system demonstrate a rhythm, which is modified and possibly initiated by carbon dioxide. It is suggested that carbon dioxide normally provides a more important ventilatory stimulus than oxygen lack.
Respiration in the Desert Locust
Authors: Miller P. L. 
Published: April 2021

ABSTRACT
During normal flight of the desert locust, auxiliary ventilating mechanisms do not appear, and dorso-ventral abdominal pumping continues at increased frequency and amplitude. When flight stops hyperventilation together with auxiliary forms appear briefly. Removal of the abdomen has shown that pterothoracic and neck ventilation are adequate for sustained flight. Spiracles 2 and 3 open wide during flight: when flight is weaker they make incipient closing movements. A central inhibitory reflex controls their activity, in addition to the peripheral action of carbon dioxide on spiracle 2. The incipient closing movements are shown not to have a functional significance; they are probably the expression of two competing mechanisms, and may arise by negative induction. Spiracles 1 and 4-10 remain synchronized with ventilation, and thereby permit adequate ventilation of the central nervous system. The isolation of the pterothoracic tracheal system is enhanced by the occlusion of two pairs of cross-links. The occlusion of a further three pairs in the prothorax and head ensures that the head has priority on the inspired air. The occlusion of all the cross-links takes place after the first instar, at which time spiracle synchronization first regularly appears and a directed airstream becomes possible. In flight there are two largely independent ventilating systems. The first, a two-way system, ventilates the flight muscles through the open spiracles 2 and 3 and is pumped by the flight movements. The second, a one-way system, ventilates primarily the central nervous system and is pumped by the abdomen, in through the dorsal orifice of spiracle 1, and out through spiracles 5-10.
Gliding Flight of the Fulmar Petrel
Authors: Pennycuick C. J. 
Published: April 2021

ABSTRACT
The basis used for estimating lift and drag coefficients is explained. A method of obtaining a photograph of a bird flying at known airspeed and rate of sink is described. 96 % of the speed measurements fall between 22 and 65 ft./sec., the average being 40 ft./sec. A maximum lift coefficient of 1-8 can be achieved. Wing area is reduced with increasing speed. The feet are used as airbrakes. A comparison of the minimum drag coefficient (0·06) with the maximum estimated power output of the pectoral muscles leaves only a narrow margin of power available for climbing. The performance diagram gives a minimum gliding angle of 1 in 812, and a minimum sinking speed of just under 4 ft./sec. The fulmar has apparently sacrificed the ability to soar dynamically over the sea in order to be able to fly slowly and thus utilize light upcurrents at cliff faces.
The Incorporation of 14C from Sodium Acetate-2-14C into the Amino Acids of the Soil-Inhabiting Nematode, Caenorhabditis briggsae
Authors: Nicholas W. L. , Dougherty Ellsworth C. , Hansen Eder Lindsay , Holm-Hansen Osmund , Moses Vivian 
Published: April 2021

ABSTRACT
The nematode, Caenorhabditis briggsae, was cultured axenically in a mixture of chick embryo extract, autoclaved liver extract and sodium acetate-2-14C. A protein hydrolysate was prepared from the worms and the eggs which were collected from the cultures. Chromatography and radioautography were carried out in a study of the amino acid composition of the hydrolysate. The following amino acids were found labelled : aspartic acid, glutamic acid, alanine, proline, glycine, serine. Cystein and cystine were oxidized to cysteic acid which was also labelled. The following amino acids were not labelled: arginine, histidine, lysine, methionine, threonine, tyrosine, valine and the combined spot representing phenylalanine, leucine and isoleucine. Tryptophane would have been destroyed by our method of hydrolysis. Since the labelled amino acids are synthesized by the worm, it is suggested, tentatively, that they are not required in an otherwise adequate diet. So far as the unlabelled amino acids are concerned, it is suggested, on the basis of the results of certain culture experiments (published separately) that, with the probable exception of tyrosine, they are essential in the diet of C. briggsae.
A Cineradiographic Study of the Central Circulation in the Hagfish, Myxine Glutinosa L
Authors: Hol Ragnar , Johansen Kjell 
Published: April 2021

ABSTRACT
Since Müller (1835) published his pioneer monograph on the morphology of myxinoids, scientists have shown great interest in these phylogenetically important forms. Although works have been presented unabated since then, very few deal with the physiology of these species and almost nothing is known regarding the functioning of their circulatory system.
Locomotory Rhythms in Carcinus Maenas (L.) From Non-Tidal Conditions
Authors: Naylor E. 
Published: April 2021

ABSTRACT
Locomotor activity has been continuously recorded by aktograph in Carcinus maenas (L.), using (a) ‘dock crabs’ from non-tidal docks, and (b) ‘shore crabs’ from the intertidal zone. Dock crabs, kept in continuous light, either dim or bright, show a temperature-independent rhythm. During the first 24 hr. large peaks occur after dusk and just before dawn, with smaller peaks during the day. Each daytime peak occurs about 12–13 hr. later than a night peak. Subsequently all the peaks drift, occurring about 50 min. later each day. Dock crabs kept in a day/night light regime do not show this drift. Shore crabs, after 4–8 weeks in non-tidal aquaria, behave in the same way as dock crabs. It is suggested that the drifting of the peaks represents an expression of endogenous tidal rhythmicity and a ‘multiple clock’ hypothesis is postulated to account for the control of rhythmicity.
The Nutrition of the Central Nervous System in the Cockroach Periplaneta Americana L
Authors: Treherne J. E. 
Published: April 2021

ABSTRACT
14C-labelled glucose injected into the cockroach was found to be rapidly converted to trehalose, only small amounts remaining in equilibrium with the disaccharide in the haemolymph. The entry of these sugars into the cockroach central nervous system was studied by following the increase in radioactivity within the abdominal nerve cord after the injection of radioactive glucose into the haemolymph. The levels of radioactivity increased at closely similar rates in different parts of the abdominal nerve cord. The influx of sugars into the nerve cord was calculated to be equivalent to 1·09 mM. glucose/l. of nerve cord water/min. The greater part of the 14C entering the nerve cord originated from the trehalose, only about 7% being derived from the small amount of glucose in the haemolymph. The movement of the relatively small number of glucose molecules into the nerve cord occurred, nevertheless, at approximately 2·5 times the rate of the larger trehalose molecules. Chromatographic analysis revealed that more than half of the absorbed 14C was incorporated as glutamic acid and glutamine in the nerve cord. Smaller amounts of glycogen, trehalose, glucose, aspartic acid and occasional traces of alanine were found. In the isolated nerve cord substantial amounts of alanine accumulated, the formation of the other amino acids being reduced. 14CO2 production in vitro was found, after 1 hr., to represent only about 1 % of the total activity within the nerve cord. The results demonstrate a linkage of carbohydrate and amino acid metabolism and represent circumstantial evidence for the presence of the tricarboxylic acid cycle enzymes in the central nervous system of this insect.
Locomotor Movements in the Spinal Pigeon
Authors: Cate J. Ten 
Published: April 2021

ABSTRACT
The lumbosacral spinal cord is able to co-ordinate locomotor movements of the hind limbs. A spinal bird under normal circumstances is unable to walk since it can no longer maintain the upright posture in consequence of the disconnexion of the higher centres. When a spinal pigeon is fixed in a carriage, so that its legs reach the ground, true walking movements in the the hind limbs can be elicited by painful stimuli applied to the hindpart of the body. In this way the pigeon can move over relatively great distances. A flight or evasion reflex can also be elicited by stimulation of the skin of the coccyx and anus. The spinal cord of birds shows a high degree of autonomy of the lower centres in the co-ordination of walking movements. The higher centres initiate and regulate these movements.
The Giant Fibre Reflex of the Earthworm, Lumbricus Terrestris L.
Authors: Roberts M. B. V. 
Published: April 2021

ABSTRACT
The purpose of this investigation was to locate the site of fatigue in the giant fibre reflex of the earthworm. The following sites do not show rapid fatigue on repetitive stimulation : contractile mechanism of muscle, neuromuscular junctions, junctions in the course of the motor neurone tracts. Rapid failure of transmission (accommodation) occurs between the sensory neurones and the giant fibre, and between the giant fibre and the motor neurones.
Maternal Age and Developmental Variability
Authors: Parsons P. A. 
Published: April 2021

ABSTRACT
Evidence is presented showing that in Drosophila egg-length variability and stemo-pleural chaeta number asymmetry, which are both measures of developmental stability, usually increase with age parabolically, so that both these characters decrease at first to a minimum between the 5th and 12th days of maternal age, then increase to a maximum, although the initial decrease in variability may not necessarily be significant. Maximum hatchability probably occurs at the time of maximum developmental stability. At the time of maximum developmental stability, growing the flies at the extreme temperature of 30° C. has least effect on stemo-pleural chaeta number asymmetry. At this time, therefore, the organism is best buffered against the stresses of the external environment. It is concluded from these studies, and from studies in the mouse and from the literature, that there is an optimum maternal age when the offspring will, in general, be fittest as measured by maximum developmental stability, viability and reproductive ability. It is argued that these results are of application to man, although factors such as variable parental expenditure in man could complicate the situation.