bluuebunny/crossref_metadata_2025 huggingface dataset:
The Efficiency of Adaptive Structures in the Nymph of Rhithrogena Semicolorata (Curtis) (Ephemeroptera)
Authors: Stuart A. M.
Published: April 2021

The current-resisting powers of Rhithrogena semicolorata Curtis have been investigated and measured, and compared with those of Ecdyonurus sp. The part played by the gills as organs of adhesion is considered, and they are found to contribute little to the current-resisting powers of the nymph. The claws are regarded as being of more importance to the animal in clinging than the gills. The dorso-ventral flattening of the animal is considered to be a creviceseeking adaptation, and not a current-resisting one.
The Occurrence of 5-Hydroxytryptamine in Scorpion Venom
Authors: Adam K. R. , Weiss C.
Published: April 2021

The constituents of scorpion venom have not yet been fully identified. During preliminary investigation of the venom of Leiurus quinquestriatus by paper chromatography, a spot corresponding in position to that due to 5-hydroxytryptamine (HT) was seen. This paper is concerned with the methods of identification and assay of this substance in venom, and also considers the histochemistry of the venom gland in relation to this finding.
A Conductimetric Method for the Estimation of Small Quantities of Ammonia
Authors: Shaw J. , Staddon B. W.
Published: April 2021

A method is described for the estimation of small quantities of ammonia down to 0·001 µg. N. The principle of the method is that ammonia is liberated from the sample and recovered in a solution of standard acid by Conway’s diffusion method; the electrical conductance of the acid falls as ammonia is absorbed, due to the difference in the mobility of hydrogen and ammonium ions. The results of estimations on standard ammonium sulphate solutions and biological fluids are tabulated. The method can deal with quantities down to 0·005 Mg-ammonia-N with an error <±2% (standard deviation), 0·001 µg. ammonia-N with an error ±6−8%. An account is given of the construction of small diffusion chambers and small conductivity cells.
The Effect of Temperature On the Waterproofing Mechanism of an INSECT
Authors: Beament J. W. L.
Published: April 2021

Previous methods for determining the temperature characteristics of the permeability to water of insect cuticle are criticized on five fundamental points, and in particular it is shown that they do not measure the temperature of the cuticle which will be substantially different from that of the surrounding air. The physical principles for accurate measurement are outlined, involving the accurate control of air temperature and air circulation, the measurement of cuticle temperature and of water loss within a sealed enclosure, and the assessment of true saturation deficiency. Apparatus for meeting these requirements and making these measurements is described. Determinations have been made of the permeability of the cuticle of Periplaneta americana nymphs. When the permeability is plotted against cuticle temperature a sudden and substantial increase in permeability is seen to take place at around 30° C. The temperature at which this change occurs is higher the longer the time which has elapsed since the nymph previously moulted. A method of measuring the permeability of the cuticular grease, when spread as a layer over an isolated water droplet, is described. This layer, whose thickness is of molecular dimensions, has much greater absolute impermeability to water than the thick grease on the insect. It also exhibits a sudden increase in permeability at about 30° C., and the order of change is considerably greater than that found with intact cuticle. The findings are quantitatively compatible with the postulate that, at lower temperatures, the grease on the cockroach consists of an orientated ‘monolayer’ organized by the attraction of its polar groupings for the aqueous cuticle surface underlying it, together with a much greater thickness of unorganized grease above it. In absolute units, the grease is about five times as permeable to water as is the ‘monolayer’, but at the transition temperature the measurements agree with the supposition that the molecular organization of the ‘monolayer ‘breaks down into the disorganized state of the major part of the grease with a corresponding increase in permeability. The suggestion that films of grease on water, and the lowermost portion of the grease on the animal, have orientated molecular organization is supported by some observations on the effect of dust particles on the films and by information previously published.
The Induction and Termination of Facultative Diapause in the Chalcid Wasps Mormoniella Vitripennis (Walker) and Tritneptis Klugii (Ratzeburg)*
Authors: Schneiderman Howard A. , Horwitz Judith
Published: April 2021

Many insects exhibit a facultative diapause which is under the control of specific environmental factors. When the insect enters diapause growth and development cease. The end of diapause is signalled by the resumption of development. In most instances the environmental agencies that cause diapause affect the generation that will enter diapause, but occasionally a stimulus applied to the maternal generation affects the post-embryonic stages of the progeny. Commonly in facultative diapause, normal growth proceeds for several moults after the application of the stimulus, and development ceases only at a later stage. Whatever the mechanism which finally prevents moulting and produces diapause, it does not interfere with intermediate moults. The present report defines the extrinsic factors that cause facultative diapause in the last larval instar of two parasitic wasps and analyses in detail the mechanism of diapause termination.
Measurement of Dissolved Oxygen in Swamp Waters. Further Modification of the Winkler Method
Authors: Beadle L. C.
Published: April 2021

A modification of the iodine-difference Winkler method is described which involves a preliminary clarification of a single sample, from which two smaller samples are siphoned. This makes possible estimations on extremely muddy and polluted water and avoids an error in the standard iodine-difference method which is very large with highly polluted waters. The iodine is added with the clarifying reagents to the original sample, thus avoiding the necessity for quantitative addition of iodine to two separate samples, which is another potential source of error in the standard method. Estimations on swamp water saturated with air under standard conditions indicate that the method is accurate to within 0·2 mg. O2/l. With polluted water, having an oxidation-reduction potential (Eh) of less than + 100 mV.,’negative’ figures for oxygen content are obtained. The cause of this phenomenon could not be discovered but, since this potential indicates anaerobic conditions, the method is not thereby affected. An improved iodine-titration end-point is described involving the use of a magnetic stirrer. Direct spectrophotometric estimation of iodine is shown to be as accurate as, and very much more rapid than titration, and particularly suited to the iodinedifference method.
Studies On the Feeding and Nutrition of Tuberolachnus Salignus (Gmelin) (Homoptera, Aphididae)
Authors: Mittler T. E.
Published: April 2021

Since Tóth (1940) questioned that the dietary nitrogen supply of aphids is adequate for their growth and reproduction, considerable controversy has existed regarding the necessity and ability of aphids to supplement their dietary nitrogen supply with atmospheric nitrogen through the agency of their symbiotic micro-organisms. Few data are available, however, on the amounts of nitrogen actually ingested, excreted, and assimilated by aphids. The aim of the present investigation was to determine these data for Tuberolachnus salignus (Gmelin), and to resolve the controversy for this species.
The Internal Rhythm of Reproduction in Xerophilous Birds Under Conditions of Illumination and Darkness
Authors: Marshall A. J. , Serventy D. L.
Published: April 2021

A report that total darkness is more effective than illumination in the production of spermatogenesis in young of the xerophilous budgerygah is shown to be due to a misinterpretation of results. An internal rhythm of reproduction allows young male zebra finches (like young budgerygahs) to produce spermatozoa within 60 days in almost total darkness when provided with plenty of food and water at laboratory temperatures. Oocytes enlarge only slightly. Both sexes come into breeding dress in the dark. Various conditions of illumination (including decreasing photoperiods) cause in both sexes greater gametogenetic activity than occurs in darkness. Both budgerygah and zebra finch are xerophilous. They are opportunist breeders after rainfall, irrespective of season. Although they retain an ancestral capacity to respond to photostimulation, any such tendency under natural conditions could be over-ridden by external inhibitors. The rapid production of spermatozoa (within 60 days) is in both parrot and finch a physiological aspect of drought adaptation enabling very young birds to reproduce quickly whenever environmental conditions are propitious.
Comparison of Dehydration and Hydration of Two Genera of Frogs (Heleioporus and Neobatrachus) that Live in Areas of Varying Aridity
Authors: Bentley P. J. , Lee A. K. , Main A. R.
Published: April 2021

Ability to take up water in response to dehydration and injection of posterior pituitary extract was measured in two genera of frogs, Heleioporus and Neobatrachus, that live in areas of varying aridity in south-west Australia. Species of Neobatrachus from dry areas took up water more rapidly than those from less dry ones. No such correlation could be seen in the species of Heleioporus. No differences could be seen in the ability of any of the animals to withstand desiccation. These findings are discussed in relation to the animals’ behaviour in its natural environment.
The Migration of Spermatozoa in the Female of Rhodnius Prolixus Stal
Authors: Davey K. G.
Published: April 2021

Removal of the opaque accessory glands from a male Rhodnius prevents the normal migration of the spermatozoa in a female which is inseminated by it. The opaque accessory secretion induces rhythmic contractions in the oviducts, probably by acting through a peripheral nervous system. Paralysis of the muscles of the female without interfering with the motility of the spermatozoa prevents the ascent of the spermatozoa. Killing the spermatozoa in the bursa has no effect on their subsequent migration. The central nervous system is not essential for the migration. It is concluded that the migration of spermatozoa in the female of Rhodnius proxlixus is a result of rhythmic contractions set up in the oviduct by the opaque accessory secretion of the male acting through a peripheral nervous system. Evidence in the literature suggests that the mechanism may operate in a number of spermatophore-forming species.
Studies on the Myoneural Physiology of Echinodermata
Authors: Pople W. , Ewer D. W.
Published: April 2021

Spontaneous activity is a well attested characteristic of holothurian muscle (Hill, 1926; du Buy, 1936a, Wells 1942). Some preparations show regular rhythmical contractions and have been used to test pharmacological reagents (Lutz, 1930; Wyman & Lutz, 1930; Iriye & Dille, 1941), while in other preparations the spontaneous activity is so variable that this is not considered possible (Riesser, 1933 ; Bacq, 1939; Ambache & Sawaya, 1953; Welsh, 1954). For certain preparations there has been no record of spontaneous activity (Morin, 1931 ; Fischer, 1938 ; Steinbach, 1940 ; Galambos, 1941 ; Prosser, Curtis & Travis, 1951 ; Prosser, 1954; van Weel, 1955). The variations between different preparations suggest that spontaneous activity is not an inevitable property of holothurian muscle, and in fact Tao (1927) and Buddington (1937) have shown that such activity depends, in part, on the presence of intact nervous tissue. Buddington (1937) studied the cloacal breathing of Thyone, and showed that the characteristic patterns of the spontaneous contractions of isolated muscles of the cloacal complex relate to the inherent functions of each muscle in the behaviour of the animal.
Flight Activity in the Blowfly, Calliphora Erythrocephala, In Relation to Wind Speed, with Special Reference to Adaptation
Authors: Digby Peter S. B.
Published: April 2021

A study has been made of the effect of wind speed on the flight activity of a population of the blowfly Caltiphora erythrocephala in a small wind tunnel. Under the experimental conditions wind has an activating effect up to about 0’·7 m./sec., above which it inhibits flight. Below 0·5 m./sec., activity decreases rapidly with decrease of wind speed and then remains at or close to the lower value. The increase of activity arising from increase of wind speed is much slower, the state of low activity tending to persist. At speeds between 0·5 and 4·5 m./sec. the changes of activity in response to both increase and decrease of wind are very rapid and are followed by a considerable degree of adaptation in each case. Inhibition of activity by the change of wind speed from 0·5 to 4·5 m./sec. and to 8·0 m./sec. results from the movement of the third antennal joint relative to the head. When this antennal movement is prevented, the change to 4·5 m./sec. causes activation if the initial activity is low, and the change to 8·0 m./sec. causes an increase of walking activity although flight is decreased for mechanical reasons. Exposure to the higher speeds causes an additional depression of activity not dependent on movement of the third antennal joint.
The Effect of Temperature Changes on the Thyroid-Pituitary Relationship in Teleosts
Authors: Fortune P. Y.
Published: April 2021

It is confirmed that TSH has a more marked effect on the teleost thyroid at high temperatures. The secretion of TSH is increased at high temperatures. The temperature to which the animal is subjected prior to the experiment has no long-term effect on thyroid activity. The thyroid-pituitary relationship is affected by temperature changes, and it is suggested that the TH : TSH ratio may be set at different levels by altering the environmental temperature.
The Electrical and Mechanical Responses of the Prothoracic Flexor Tibialis Muscle of the Stick Insect, Carausius Morosus Br
Authors: Wood D. W.
Published: April 2021

The prothoracic flexor tibialis muscle of Carausius morosus consists of two lateral rows of pinnately arranged muscle units. Motor nerve endings of the ‘Doyére-cone’ type are distributed at intervals of approximately 60 p along each fibre. Each motor ending is probably innervated by two axons. Two types of responses have been found in the muscle fibres: (i) ‘fast’ electrical responses resembling the action potential of vertebrate muscles, associated with twitch-type contractions of the fibres; (ii) ‘slow’ readily facilitating responses resembling end-plate potentials, associated with slow, smooth contractions of the muscle, and with the maintenance of tonus. There is no evidence of peripheral motor inhibition. The muscle bathed in haemolymph is capable of developing a tetanus tension of 800 g./cm.2 cross-sectional area of individual muscle fibres. The tetanus : twitch ratio is over 25:1. Pharmacological substances which affect excitable tissues of other animals have no effect on the fast response. Progressively lowered temperatures lengthen the time course and reduce the amplitude of the fast response, but an active membrane response remains at 50 C. Refractoriness is evident near the peak of the fast response. The junctional potentials will summate if sufficiently close in time. It is suggested that the process underlying the fast response in Carausius is similar to that in the locust and in vertebrates ; but neuromuscular transmission does not appear to be cholinergic.
Excretion by the Malpighian Tubules of the Stick Insect, Dixippus Morosus (Orthoptera, Phasmidae): Amino Acids, Sugars and Urea
Authors: Ramsay J. A.
Published: April 2021

Contrary to expectation, it is found that metabolically useful substances pass into the urine and are reabsorbed in the rectum. The kinetics of penetration have been investigated for six amino acids, three sugars and urea. The evidence indicates that these substances enter the urine by passive diffusion. The role of the Malpighian tubules in the insect’s excretory system is discussed in the light of these findings. It is suggested that the tubule is primarily a means whereby all soluble substances of low molecular weight are removed from the haemolymph and that in this respect it has analogies with the glomerulus as well as with the tubule of the vertebrate nephron.
Further Studies on Ionic Regulation in the Muscle Fibres of Carcinus Maenas
Authors: Shaw J.
Published: April 2021

The muscle fibres of Carcinus maenas contain 91 mM./kg. fibre water of acid soluble phosphate compounds, of which arginine phosphate is the most abundant. These compounds behave passively under conditions of blood dilution and the phosphate radicals do not exchange freely with inorganic phosphate in the blood. Muscle potassium exchanges freely and completely with the blood potassium. The exchange constant is about 0·4 hr.−1. In the normal fibre potassium ions are approximately in equilibrium with those in the blood. Potassium is lost from the muscle when the blood potassium concentration is reduced, but both the muscle-to-blood potassium ratio and the membrane potential are increased. The behaviour of potassium appears to be largely passive but there may be some small active component in its retention. Muscle sodium exchanges very rapidly and completely with blood sodium. The exchange is complete in 10 min. Sodium is also lost rapidly from the muscle to Ringer solutions with a reduced sodium concentration. It is suggested that the bulk of the muscle sodium is situated in a region distinct from the true fibre interior and that sodium ions are rigidly excluded from the latter. These results are discussed in relation to the adaptation of the muscle fibre to reduced blood concentrations.
Unidirectional Movement Fibres from a Proprioceptive Organ of the Crab, Carcinus Maenas
Authors: Wiersma C. A. G. , Boettiger E. G.
Published: April 2021

Proprioception in the legs of arthropods arises in receptor ceils more closely associated with structures of the joints than with muscles. Sensitive endings are located in special internally placed organs (Barth, 1934; Burke, 1954; Alexandrowicz & Whitear, 1957). Studies of the action potentials in the leg nerve during mechanical manipulation of the leg joints in Limulus (Pringle, 1956) and in certain arachnids (Pringle, 1955) have shown the presence of several types of proprioceptive endings. Slow-adapting tonic position fibres, some responding at the flexed and others at the extended positions, were shown to have their endings situated so as to react to strains in the cuticle. The rapidly adapting phasic fibres, however, originate in some internal structures, different fibres responding to the two directions of movement.
The Composition of the Blood of the Shore Crab, Carcinus Moenas Pennant, in Relation to Sex and Body Size
Authors: Gilbert A. B.
Published: April 2021

The influence of body size and sex on the total osmotic pressure (O.P.) and blood conductivity of the shore crab was investigated. In both sexes the O.P. fell steadily as body weight increased. At any body weight the O.P. of the blood of male crabs was significantly higher that that of females. Blood conductivity increased in both sexes until a maximum was reached at a weight of about 35 g. Thereafter the conductivity fell as the weight increased. There was no significant difference in blood conductivity between male and female crabs below 35 g. body weight. Above 35 g. the conductivity of males was significantly higher than that of females.
A New Tonometric Method for the Determination of Dissolved Oxygen and Carbon Dioxide in Small Samples
Authors: Jones J. D.
Published: April 2021

A microtonometric method is described whereby tensions of carbon dioxide, oxygen and nitrogen can be determined in fluid samples of 0·3 ml. volume or less, each determination taking 20·25 min. Replicate determinations of the tensions of carbon dioxide, oxygen and nitrogen give maximum coefficients of variability of 3·0, 2·2 and 1·2%, respectively. A comparison of the present method with a micro-Winkler method for the determination of dissolved oxygen shows a close agreement; the mean percentage difference being 3·0.
The Respiratory Centre in the Tench (Tinca Tinca L.)
Authors: Shelton G.
Published: April 2021

The effects of brain transections on the breathing movements of the tench are described. The whole of the mid- and forebrain, and the cerebellum, can be removed without producing any change in the breathing movements. Normal movements continue after section of the IXth and Xth cranial nerves. Transections of the spinal cord and posterior medulla are without effect on the breathing rhythm until they reach a level just behind the facial lobe. The breakdown of respiration produced by transection at this level is interpreted as being due to removal of part of the respiratory centre. Rhythmically repeated movements in which the opercula abduct and the mouth closes are seen after transection in the posterior parts of the medulla. These movements are thought to be due to activity in neurones which are responsible for co-ordination of the coughs in the intact animal. These neurones are situated in the anterior part of the medulla, beneath the cerebellum.
Respiration Rates of Worker Honeybees of Different Ages and At Different Temperatures
Authors: Allen M. Delia
Published: April 2021

The respiration rates of individual adult worker bees confined in small gauze cages were determined over a range of temperatures between 7 and 46°C. The respiration rates usually remained constant over a period of 1 hr., although at 7, 12° C., and possibly at 17° C. there were indications of a decrease with time, and at 42 and 46° C. indications of an increase with time. Fluctuations which would have reflected variable activity during any of the experiments were rare. At each temperature studied the respiration rates increased progressively from the youngest adults (newly emerged) to the oldest measured (24–33 days). The increase was particularly marked during the first few days of adult life. The respiration rates of newly emerged and 18 hr. old adults increased progressively between 7 and 46° C., but 4–33-day-old bees showed two peaks (at 17 and 46° C.) with a depression having a minimum value at 32° C. lying between. 2-day-old bees had similar peaks at 22 and 46° C. It is suggested that the first peak in the respiration rate of the older bees occurred at the lowest temperature at which free movements were possible, and that it indicated an increased body temperature maintained by the bees to combat the effects of the low environmental temperature. The lack of this first peak in the case of the youngest bees is thought to mean that they were unable to raise their temperature above that of the environment. The information obtainable from the literature supported these conclusions; their implications in relation to the regulation of temperature within the colony are discussed. Numerical values for the oxygen consumptions of adult bees are discussed in relation to those found by other workers.
Electroencephalographic Patterns of the Goldfish (Carassius Auratus L.)*
Authors: Schadé J. P. , Weiler Ivan Jeanne
Published: April 2021

Bipolar surface electrodes were used to record electrical potentials from the brain of the goldfish, Carassius auratus L. Characteristic patterns of spontaneous electrical activity were described for telencephalon, mesencephalon, cerebellum and medulla oblongata. Changes in these patterns under deepening urethane narcosis were noted. Rapid repetitive flashing light caused a change in the normal pattern of the mesencephalon which resembled the mammalian arousal. High-frequency (18–24 cyc./sec.) low-amplitude activity replaced the characteristic low-frequency waves (7–14 cyc./sec.); the lower-frequency activity returned 1–5 min. after cessation of stimulation. Responses to single light flashes were described from the mesencephalon and cerebellum. An ‘A complex’ from the mesencephalon consisted of two to four rapid diphasic spikes, with a latency of 30–40 msec., duration of 40–50 msec., and amplitude of about 100 μ.V. A ‘B complex’ consisted of a large negative wave, duration 90–110 msec, and amplitude 100–200 μ,V., followed by a small positive deflexion, and a slow negative after-potential. The cerebellar response had a latency of 60–80 msec., duration of 100–120 msec., amplitude of 80–125 μV. The nature of these two components was discussed. Monocular blinding abolished the response to light in the contralateral half of the optic tectum and in the cerebellum. The amplitude of the low-frequency spontaneous activity characteristic of the mesencephalon was reduced in the contralateral tectum. Regional differences in the tectal response to single light flashes were described. Microelectrodes were used to record the photic response from deeper tectal layers. After destruction of parts of the retina by electrocautery, a disappearance of the A complex and 40–50% reduction of the B complex was observed in restricted tectal areas. The distribution of the areas of changed response was shown to correspond to a coarse overlapping projection of retinal quadrants of the fish eye on to the contralateral optic tectum. A possible basis for the localization of this projection, in agreement with anatomical and electrophysiological findings, was described.
Long-Term Facilitation in A Swimming Sea Anemone
Authors: Wilson Donald M.
Published: April 2021

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

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

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

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

Many 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

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

Measurements 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

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

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

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

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

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

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

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

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

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

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

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

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.