bluuebunny/crossref_metadata_2025 huggingface dataset:
The Possible Involvement of An Amino Acid Decarboxylase in the Stimulation of the Pericardial Cells of Periplaneta by the Corpus Cardiacum
Authors: Davey K. G.
Published: April 2021

Semicarbazide hydrochloride and isonicotinic acid hydrazide, which are both inhibitors of phosphopyridoxal-dependent systems, inhibit the increase in the rate of beating of hearts which is brought about by breis of corpora cardiaca. This inhibition is partially reversed by phosphopyridoxal. Semicarbazide decreases the percentage of argentaffin-positive cells among pericardial cells exposed to breis of corpora cardiaca. DOPA increases the rate of beating of the isolated heart. This increase is mediated by the pericardial cells and is inhibited by semicarbazide. The inhibition by semicarbazide is reversed by phosphopyridoxal. It is suggested, as a working hypothesis, that the hormone from the corpus cardiacum stimulates the pericardial cells to produce an amine from an amino acid by the action of the appropriate amino acid decarboxylase. The hormone intervenes either by causing the cells to produce more of the amino acid, or by unmasking the amino acid which is pictured as being protected from the enzyme in the unstimulated cell.
Co-Ordination of Successive Activities in An Aphid. the Effect of Flight On the Settling Responses
Authors: Kennedy J. S. , Booth C. O.
Published: April 2021

Previous evidence that fresh-winged adult aphids become increasingly ready to settle down on a leaf the longer they have flown beforehand, and that this effect is appreciable after less than 1 min. flight, was confirmed with aphids allowed to fly and alight freely without interference. The settling responses initiated after flight were quickly inhibited again by an unsuitable leaf, with reversion to flight, but repeated flights had a cumulative effect. The excitability of the settling responses increased as an after-effect of flights in which the excitability of flight itself (measured by the rate of climb) was not falling and was even increasing. It is concluded that settling is not released by flight but is positively ‘primed’ while it is inhibited by flight, these two activities having been shown to be centrally antagonistic. Settling may be further promoted by some peripheral physiological feedback during long flights when the rate of climb falls, but this is a secondary, merely reinforcing effect. The primary effect is given the name ‘antagonistic induction’. It resembles successive induction or rebound in lower reflex action As a principle of nervous integration at the behavioural level it calls in question previous assumptions concerning internal drives in aphids and other animals. Host plant selection occurred as a result of the sequence of settling responses being broken off at an earlier stage on one kind or age of leaf than another. Most commonly the difference of behaviour appeared only after a first probe, but following very short flights discrimination was sometimes observed without any probing.
Osmoregulation in Ligia Oceanica and Idotea Granulosa
Authors: Todd Mary E.
Published: April 2021

The osmoregulatory response of Ligia oceanica and Idotea granulosa to the range of the experimental variables was similar. They were both hyperosmotic relative to the medium and the difference between internal and external concentration increased as the salinity of the medium decreased. In 100 % sea water the osmotic concentration of the blood of Ligia oceanica was markedly above that of the medium, whereas in Idotea granulosa the blood was only marginally hyperosmotic. In Ligia oceanica the blood concentration changed little in 100 and 75 % sea water, but dropped significantly between 75 and 50% sea water, whereas blood concentration in Idotea granulosa dropped significantly throughout the test range of salinities. The more efficient osmoregulation of Ligia oceanica in 25 % sea water is reflected in the mean freezing-point depression of the blood Δi = 1 · 65, compared with Δi = 0 · 90 in Idotea granulosa. In both species the osmotic concentration of the blood was influenced by season, by temperature and by a temperature-salinity interaction. Neither size nor sex of the animal influenced osmotic concentration of the blood.
Delayed Responses in Octopus
Authors: Dilly P. N.
Published: April 2021

Octopuses were tested for their ability to perform delayed responses after varying delays and brain lesions. Octopuses delayed for 10 sec. were capable of accurate performance without training. In order to make a correct response after 20 or 30 sec. delays some ‘learning’ is needed. Animals without vertical lobes or without median superior frontal lobes delayed for 30 sec. responded correctly. The majority of correct attacks were ‘swimming attacks’ in which the animal swam through the water without contacting the walls of the tank. ‘Shaking up’ the animals and disturbing them so that any orientating contact between the octopus and the door and sides of the tank was destroyed, did not decrease the accuracy of the response. The time taken for the response in these experiments was slightly increased.
Comparative Physiology of the Vertebrate Autonomic Nervous System
Authors: Burnstock G. , Campbell G.
Published: April 2021

A histological study of the structure of the urinary bladder of the ringtail possum has been made. The innervation of the bladder has been studied in vitro, using the technique of analytical pharmacology. The bladder has well-defined inner longitudinal and outer circular muscle layers. Nerves supplying the bladder are found both in the pelvic nerves and in the vesical nerves which run with the vascular supply of the bladder fundus. Ganglia have been demonstrated along the trunks of the vesical nerves and also aggregated at the bladder neck. The response of the bladder to stimulation of either nerve supply in situ or in vitro is always a simultaneous contraction of both longitudinal and circular muscles. Inhibitory responses to nerve stimulation have never been observed. The optimal frequency for stimulation of these nerves at 30° C. is 50 pulses/sec. The bladder is contracted by ACh and 5-hydroxytryptamine, but is relaxed by adrenaline, noradrenaline and histamine. The response to nerve stimulation is reduced by atropine and potentiated by eserine. Adrenergic blocking agents do not affect the nerve-mediated response unless they also affect the response to applied ACh in a similar manner. Ganglionic blocking agents, in concentrations which do not reduce the response to ACh, cause up to a 40% reduction of the response to stimulation of either the vesical or the pelvic nerves. It is concluded that the nerve fibres supplying the possum bladder are cholinergic, perhaps 40 % of them being stimulated pre-ganglionically. The evolutionary significance of these observations is discussed. Some points of pharmacological interest have been discussed in relation to drug actions on placental mammal preparations.
Studies On the Mode of Action of the Diapause Hormone in the Silkworm, Bombyx Mori L
Authors: Hasegawa Kinsaku
Published: April 2021

The action of the diapause hormone has been studied by injecting extracts of the heads of male moths or of the brain-suboesophageal ganglion complexes of pupae into pupae expected to produce non-diapause eggs. The effect of the injection of hormone upon young oocytes is to make them develop into diapause eggs. Older oocytes, which have already acquired non-diapause characters, are not affected. The hormone is almost completely inactivated when injected on the day of pupation. The hormone is most effective when injected into pupae 2-3 days old, at which stage the ovarioles have started to grow vigorously. It is ineffective 1-2 days before adult emergence, by which time all the oocytes have acquired non-diapause characters. The hormone is inactivated in all pupae irrespective of whether they are destined to produce diapause eggs or non-diapause eggs. Inactivation of diapause hormone (in contrast to that of juvenile hormone) is partially relieved by exposure to low temperature or by simultaneous injection of indian ink. The extracts prepared as in (1) above do not serve as a stimulant for the brain causing the suboesophageal ganglion to produce diapause hormone. The action of the extract faithfully reflects the function of the diapause hormone which originates in the suboesophageal ganglion.
Oxygen Requirements and the Physiological Suppression of Supernumerary Insect Parasitoids
Authors: Fisher Roderick C.
Published: April 2021

The oxygen content of the haemolymph of mature larvae of Ephestia kühniella has been measured in healthy individuals and in those parasitized by the ichneumonid Nemeritis canescens. In the latter the oxygen content decreases with the progress of parasitism. The respiratory rate of first, second- and third-instar larvae of Nemeritis has been measured and found to increase rapidly at the end of the first instar, at about the time at which the phenomenon of physiological suppression appears. The partial pressure of oxygen in the gas mixture surrounding the Ephestia larva affects the oxygen content of its haemolymph proportionally and so was used to alter the availability of oxygen to the parasite in vivo. The survival of Nemeritis larvae increases with the availability of oxygen in the haemolymph of its host. The capacity for survival under conditions of low oxygen tension is minimal for eggs and newly hatched larvae of Nemeritis, but rapidly increases with age. The hypothesis of physiological suppression of supernumerary parasitoid larvae by asphyxiation is discussed with respect to these observations and is held to be supported by them.
Water Balance in the Aquatic Bugs Notonecta Glauca L. and Notonecta Marmorea Fabr. (Hemiptera; Heteroptera)
Authors: Staddon B. W.
Published: April 2021

A study has been made of water balance in two closely related species of aquatic bug, Notonecta glauca L. and N. marmorea Fabr., and the mechanism appears to be the same in both. Ammonia is a major nitrogenous excretory compound and the bulk of the ionic material in the rectal fluid is in the form of ammonium bicarbonate. Water is eliminated through the excretory system and the output of water appears to be related to the output of ammonia. The relationship is such that the concentration of ammonia in the rectal fluid tends to a limiting value of about 120 mm./l. Water is gained by uptake through the cuticle and gut. The volume of water ingested is closely related to the volume of water eliminated through the excretory system and the uptake of water through the cuticle appears to be constant at about 7 % of the body weight per day. At the time of moulting the increase in weight is in part due to retention of water in the tissues and in part due to the retention of water in the rectum. It is pointed out that the mechanism by which water balance is maintained in Notonecta may not be of wide application to other aquatic insects.
Studies On the Respiration of Sea-Urchin Spermatozoa
Authors: Mohri H. , Yasumasu I.
Published: April 2021

The effect of PCO2 on the respiration and motility of sea-urchin spermatozoa was studied on Anthoddaris crassispina. Some points were also corroborated on Hemicentrotus pulcherrimus, Pseudocentrotus depressus, Paracentrotus lividus and Sphaerechinus granularis. It was found that any level of CO2 above 1 %, both in oxygen and in air, inhibited the O2 uptake of spermatozoa suspended in sea water, measured polarographically with a vibrating platinum electrode. The inhibitory effect paralleled the PCO2and was completely reversed by introducing oxygen or air. pH variations between 8·50 and 6·75 had no influence on O2 uptake, when the pH was stabilized with 0·05 Mhistidine-HCl-NaOH. O2 uptake was, however, reduced to some extent outside this range, especially on the acid side. Although the increase in PCO2 is inevitably followed by a decrease in pH, the inhibitory effect of CO2 far exceeds that caused by the reduction in pH. The O2 uptake rate was little affected by the addition of both bicarbonate and carbonate ions to the suspending medium, although the former had a slightly stimulating effect at certain concentrations. In buffered sea water, CO2 had little influence on O2 uptake even at partial pressures as high as 10% which inhibited the bulk of O2 uptake in sea water. Sperm motility was also inhibited by CO2. In this case, too, the inhibition paralleled the PCO2 and was completely reversible. The effect was more pronounced in air than in oxygen, and in dense sperm suspensions than in dilute ones. These results suggest that gaseous CO2 is the factor responsible for the inhibitory effect. The possible role of CO2 in the dilution phenomena of sea-urchin spermatozoa is discussed.
Studies on the Myoneural Physiology of Echinodermata
Authors: Boltt R. E. , Ewer D. W.
Published: April 2021

The responses to drugs of a preparation of the lantern retractor muscle of Parechinus are described. The muscle responds with a contracture to acetylcholine, but atropine is without action. Nicotine and eserine enhance the tone of a preparation, the latter also causing rapid rhythmic activity. Curare, in low concentration, enhances tone and activity but is inhibitory at higher dosages. Adrenaline inhibits activity and abolishes tone. The action of acetylcholine is antagonized by both adrenaline and curare. It is suggested that the results observed with curare and eserine are independent of their effects upon cholinergic transmission and that their seat is at the level of the motor complex of the muscle.
In VitroCulture of Embryos in the Silkworm,Bombyx MoriL
Authors: Takami Takeo
Published: April 2021

Silkworm embryos decapitated before the differentiation of neuroblasts, or before differentiation of the prothoracic glands, were cultured in vitro. Brainless embryos which developed from these decapitated explants detached the cuticle, suggesting that the’moult’ of cultured embryos does not require any hormonal action of the brain in the silkworm at least for its initiation. The prothoracic gland was not found to be necessary even for occurrence of the embryonic moult. The author’s results obtained by embryo culture in the silkworm are contrary to those obtained by ligaturing experiments in the locusts. This difference between the two cases present important questions about the nature of the moult in cultured silkworm embryos, which must be answered by further investigations.
Length of Life of the Sexes inNasonia Vitripennis(Walker) (Hymenoptera, Pteromalidae) Under Conditions of Starvation
Authors: King P. E. , Hopkins C. R.
Published: April 2021

At relative humidities of 65 and 100% the mean length of life of virgin or mated females of Nasonia vitripennis is greater than that of the males under similar conditions. The sexes showed no significant difference in their respiratory rates, as measured by Warburg manometer or Macfadyen’s continuous recording respirometer. An examination of the organs of fed and starved individuals of both sexes showed that the only major change in the organs of starved individuals which can have any bearing on the length of life is the marked reduction in length of the ovaries resulting from resorption of the mature eggs. It is suggested that the resorbed eggs supply the female with the nutriment which enables it to outlive the male when both are starved.
Control of Luminescence in Hemichordates and Some Properties of A Nerve Net System
Authors: Baxter Charles H. , Pickens Peter E.
Published: April 2021

Luminescence in Ptychodera and Balanoglossus is normally neurally mediated. The main luminescence appears to be intracellular; in addition a luminous slime is secreted. The response of individual photocytes is all-or-none, but requires neuroeffector facilitation which grades intensity by recruitment (in contrast to crustacean muscle). Repetitive discharge, both to mechanical and single electrical stimuli, is considered to be a prime factor together with interneural and neuro-effector facilitation, in determining spread of excitation in the general plexus. Four types of spread of luminescence occur, differing in conduction velocity polarization of spread, area of spread, necessary conditions for elicitation and adequate stimulus. At least three different neural pathways are involved. Prolonged autoexcitatory displays produce luminous waves arising repetitively from the same locus and from multiple loci; the general plexus is implicated. There is a diurnal rhythm of responsiveness to stimuli. This is attributed to the photocyte rather than to the nervous system.
Frog Fast Muscle: II. A Method of Measuring Internal Series Compliance
Authors: Pennycuick C. J.
Published: April 2021

Methods which have been used in the past for estimating internal series compliance are discussed. A new method is described in which measurements of (a) rate of change of tension, and (b) speed of shortening are made in the isometric and isotonic phases respectively of a contraction containing a transition from one type of contraction to the other. If the mechanical power output of the muscle is assumed the same just before and just after the transition, the total series compliance can be obtained. The method is found to agree with Wilkie’s quick-release method, provided parallel elastic structures are not carrying significant tension at the transition.
The Location of the Photoperiodic Receptors in the Aphid Megoura Viciae Buckton
Authors: Lees A. D.
Published: April 2021

Although the photoperiodic reactions of insects and mites have been studied quite extensively (Lees, 1955 ; de Wilde, 1962), the site of the photoreceptors is still unknown. The light pathway does not seem to involve the eyes. Thus Tanaka (1950) observed that the photoperiodic control of diapause in the silkworm Antheraea pernyi was not affected by cauterizing the lateral ocelli of the 4th-instar larva—a treatment that resulted in the complete disappearance of these organs in the following instar. De Wilde, Duintjer’ Mook (1959) have shown that adult Colorado beetles (Leptinotarsa decemlineata) respond normally to day-length after the compound eyes have been covered with black paint or destroyed with a cautery.

Less progress has been made in identifying the regions of light sensitivity. Geispits (1957) was able to fit an opaque hood over the head of a Dendrolimus larva which was otherwise continuously illuminated. With this covering in place for 12 hr. daily all the insects subsequently entered diapause. But none did so when only the body was shielded from light, showing that the photoreceptors were located on the head. Since the wavelength sensitivity of the visual and photoperiodic response showed some correspondence Geispits was led to the further conclusion that the eyes were in fact the photoperiodic receptors. But in view of the preceding evidence this conclusion seems questionable.
The Locomotion of Nematodes
Authors: Gray J. , Lissmann H. W.
Published: April 2021

The form and frequency of the waves passing down the bodies of small free-living nematodes (Panagrellus, Rhabditis and Turbatrix) depend on the nature of the external medium. Observations of animals moving in such media as syrup, agar gels, and dense suspensions of particles suggest that the relationship between the speed of progression of the animal to the speed of propagation of the waves along the body, depends on the relative resistance exerted by the medium to displacement of the body in directions normal to and tangential to its own surface. When swimming in water the body of a nematode yaws periodically in a transverse plane and the axis of progression does not coincide with that of the waves; the displacement of an element of the body relative to the medium depends on its position on the body. The envelope of one complete wave exhibits two characteristic nodes. A suspended particle originally situated near the anterior end of a swimming animal moves tangentially backwards along the surface of the body, but the speed at which it does so is not constant and is always much less than that at which the waves travel relative to the ground. The average speed of a particle close to the surface of the body is about one quarter of that of the waves. When plotted relative to the ground the path of displacement of a particle exhibits characteristic loops. When viewed from above and in the direction of the animal’s progression, all particles on the left side of the body traverse their loops in a clockwise direction ; all those on the right side move anticlockwise. There is a highly characteristic pattern of circulation round the body of the animal. Water in the vicinity of a wave crest moves in the opposite direction to that of the propagation of the waves, but in the same direction as the waves when situated in a wave trough. The circulation extends for a considerable distance from the surface of the body. The flow round the body of a swimming nematode is essentially the same as that in the neighbourhood of an undulating sheet of rubber. Its analysis presents an interesting but difficult hydrodynamical problem.
Rectal Absorption in the Desert Locust, Schistocerca Gregaria Forskål
Authors: Phillips J. E.
Published: April 2021

The absorption of Na, K and Cl from the rectum has been studied in locusts previously supplied either with tap water or with hypertonic saline, the latter treatment resulting in a 40 –70 % increase in the ionic concentrations in the haemolymph. Both water-fed and saline-fed locusts can absorb Na, K and Cl from the lumen of the rectum against concentration differences of up to 100-fold. The lumen is 15-30 mV. positive to the haemolymph. Absorption of Cl is certainly an active process; absorption of Na and K probably involves active processes. In water-fed locusts absorption of K is four to twelve times more rapid than that of Na, and absorption of Cl is three times faster from KC1 than from NaCl. In saline-fed locusts the relative rates of absorption of Na, K and Cl are the same as in water-fed locusts, except when the concentrations in the rectal fluid exceed those in the haemolymph. The experimental results are consistent with the hypothesis that regulation of absorption of water and of ions from the rectum is brought about by changes in the passive permeability of the epithelium rather than by changes in mechanisms of active transport.
Biology and Physics of Locust Flight
Authors: Weis-Fogh Torkel
Published: April 2021

A calorimetric method was designed which makes it possible to estimate the metabolic rate of a flying insect with an accuracy of ±10%. For the first time, the metabolic rate of a flying animal has been related to the main aerodynamic component of force, the lift. The metabolic rate of locusts increases almost linearly from 41 kcal, kg.-1 hr.-1 at 50% relative lift to no kcal, kg.-1 hr.-1 at 170%. The results are in accordance with theoretical deductions and they show that the work necessary to accelerate the oscillating wings (inertia terms) is small compared with the aerodynamic work—probably three to five times smaller. In flapping insects and small birds the metabolic rate per unit weight seems to be independent of size. The control of power is discussed.
Gill Ventilation Volumes, Oxygen Consumption and Respiratory Rhythms in Carcinus Maenas (L.)
Authors: Arudpragasam K. D. , Naylor E.
Published: April 2021

An apparatus is described for continuously measuring gill ventilation volumes in crabs. Large Carcinus pump about 1 c.c./g./min. and consume oxygen at the rate of about 0·03 c.c./g./hr. whilst smaller specimens pump up to 1·5 c.c./g./min. and consume up to 0·1 c.c./g./hr. Freshly collected crabs show persistent tidal and 24 hr. rhythms of pumping activity and oxygen consumption. In response to oxygen depletion Carcinus shows increased rates of gill ventilation and increased percentage utilization. Prolonged exposure to increased carbon dioxide results in a short-lived inhibition followed by over-compensation and then progressive inhibition of respiratory activity. The results are discussed in relation to previous work on respiration in other decapod Crustacea.
The Waterproofing Mechanism of Arthropods
Authors: Beament J. W. L. , Noble-Nesbitt J. , Watson J. A. L.
Published: April 2021

The firebrat, Thermobia, is very impermeable to the outward flow of water, losing only 0·013 mg. of water/mm. Hg saturation deficit/hr./standard animal of 30 mg. between 19 and 26° C. The permeability increases to a higher level at a critical temperature just below 30° C. and well below the optimal temperature for the insect as a whole. The waterproofing is mobile, for it regains its lower permeability on cooling below the transition temperature and is also restored a short time after abrasion. Extractions support the hypothesis that the impermeable layer is a stiff, epicuticular grease but further suggest that an imperforate lamella, perhaps a cement, lies over the grease. The live firebrat can absorb water from moist air, reaching an equilibrium between absorption and transpiration at a saturation deficit of approximately 10 mm. Hg at a temperature of 21° C. Although abrasion of the integument decreases the net rate of water uptake and lowers the saturation deficit at which equilibrium is possible, it may act only by increasing temporarily the rate of transpiration.
Visco-Elastic Properties of the Mesogloea of Jellyfish
Authors: Alexander R. McN.
Published: April 2021

The mesogloea of Scyphozoa (Cyanea and Chrysaora) differs from that of Anthozoa in having higher elastic compliance, in having a broad distribution of retardation times, and in that creep recovery is very slow. In the second of these properties the scyphozoan mesogloea resembles simple polymeric gels.
Activation of the Sodium Uptake System at High Blood Concentrations in the Amphipod Gammarus Duebeni
Authors: Lockwood A. P. M.
Published: April 2021

Some factors responsible for eliciting an increase in the rate of active uptake of sodium by Gammarus duebeni have been studied. Animals previously acclimatized to high salinities (100-161% sea water) had their blood concentration suddenly lowered by treatment with deionized water to a level similar to, but a little above, that of animals kept in 50-66% sea water. Both groups were placed in the same tracer medium, i.e. 5% sea water labelled with 22Na and with sucrose added. The animals treated with deionized water showed an influx, on average, of 4 times that of the controls from 50 to 66% sea water. No increase in influx followed treatment of animals from 161% sea water with 50% sea water or with sucrose solution isosmotic with 50% sea water, despite the fact that the osmotic gradient between 161 and 50% sea water is greater than the gradient between 100% sea water and deionized water. It is concluded that in these experiments the rate of uptake is not influenced primarily by the absolute concentration of the blood, the rate of change of blood concentration, the rate of swelling of the tissues or the extent of the blood volume. The possibility is considered that both the concentration of the urine and the rate of uptake of sodium may, in some circumstances, be controlled by an exteroreceptor which monitors the concentration of the medium and mediates its effect via a humoral system.
Excretion in the Blood-Sucking Bug, Rhodnius Prolixus Stål
Authors: Maddrell S. H. P.
Published: April 2021

The diuresis of freshly fed larvae of Rhodnius is controlled by afferent nervous information from the abdomen. This information is supplied by abdominal stretch receptors sensitive to vertical distension of the abdomen. It is most probable that the receptors are in the vertical tergosternal muscles, a trio of which occurs towards each lateral edge in abdominal segments 2−7 inclusive. It is suggested that diuresis in Rhodnius is a reflex response to the distension of the abdomen brought about by the swelling of the anterior part of the mid-gut during feeding.
Experiments On Substrate Selection by Corophium Species: Films and Bacteria On Sand Particles
Authors: Meadows P. S.
Published: April 2021

A simple method is described for determining the substrate preferences of Corophium volutator (Pallas) and Corophium arenarium Crawford. If offered a choice of its own substrate with that of the other species each prefers its own. Level of illumination and colour of substrate have little effect on choice. An animal’s size and hence its age has little effect on its substrate preferences. C. volutator prefers a substrate previously maintained under anaerobic conditions, C. arenarium vice versa. Treatments which kill, inactivate, or remove micro-organisms render sands unattractive to Corophium. These include boiling, acid-cleaning, drying, and soaking in fixatives or distilled water. Attempts to make these sands attractive again failed. Distilled water, and solutions of the non-electrolytes sucrose and glycerol at the same osmotic pressure as sea water, induce many bacteria to desorb from sand particles ; smaller numbers are desorbed in the presence of solutions of electrolytes at the same ionic strength as sea water (NaCl, Na2SO4, KC1, MgSO4, MgCl2, CaCl2). Of all these, only distilled water and solutions of MgCl2 and CaCl2 reduce the attractive properties of sands. Hence the loss of bacteria from the surface of sand grains, though related to the ionic strength and composition of the medium, is not necessarily associated with a substrate becoming unattractive.
Studies On Crop Function in the Cockroach (Periplaneta Americana L.)
Authors: Davey K. G. , Treherne J. E.
Published: April 2021

The initial hydrostatic pressure developed in the crop on feeding was independent of the osmotic concentration of the ingested glucose solution. It is calculated that the pressure increase was not the result of a simple compression of the air contained in the crop, but that the feeding process must have involved a significant release of air from this structure. The pressure pulses which developed after feeding appeared to be dependent on the same nervous pathway as that determining the frequency of opening of the proventricular valve. They also decayed at the same rate as the frequency of opening of the valve. Such a linkage between the pressure pulses and the opening of the valve might ensure a maximum pressure gradient between the lumen of the crop and the midgut. An appreciable negative hydrostatic pressure was demonstrated in the haemolymph, which, if transmitted to the lumen of the midgut, would facilitate the maintenance of the hydrostatic pressure gradient across the proventricular valve. Both the general and transient pressures within the crop decayed exponentially, there being no significant difference when solutions of different osmotic pressure were used. With a viscous solution (containing 4% methyl cellulose) the pressure changes were of the same order as with normal solutions, except that the transient pressure pulses tended to remain constant after an initial relatively rapid fall. A quantitative analysis, based on a modified Poiseuille relation, showed that the effective dimensions of the proventricular valve increased with time, the initial value of the ‘valve parameter ‘being smaller and the rate of increase more rapid with the more concentrated solution. It is concluded that variations in the effective dimensions of the valve contribute to the demonstrated control of crop-emptying at different osmotic concentrations. The possible nervous mechanism capable of controlling the release of fluid from the crop is considered.
Nervous Control of Chromatophores in Teleost Fishes
Authors: Pye J. D.
Published: April 2021

Electrical threshold curves have been obtained for the stimulation by square and saw-tooth pulses of peripheral melanophore-aggregating nerve fibres in the minnow, Phoxinus. The responses show complete independence of pulse repetition rate over a wide range. The results of von Gelei on the electrical stimulation of the spinal cord in ergotamine-treated minnows have been confirmed but it is found that the melanophore-dispersing activity may pass forwards or backwards from a stimulating electrode at any level of the spinal cord. Identical results have been obtained for melanophore-aggregating activity in non-ergotized fish. All the spinal responses are slow and incomplete at repetition rates below 10/sec. Von Gelei’s arguments for mapping the pathways of melanophore-dispersing nerve fibres are shown to be insupportable.
Nervous Control of Chromatophores in Teleost Fishes
Authors: Pye J. D.
Published: April 2021

Responses of melanophores to injections of adrenalin or L-noradrenalin have been examined with and without prior injection of ergotamine. Responses of the melanophores of isolated skin preparations in solutions containing adrenalin or L-noradrenalin have been examined with and without prior injections of, or direct exposure to, solutions of ergotamine. No reversal of response could be found in any of the above cases. Responses of melanophores following injections of Rogetine (an alternative adrenergic blocking agent) are quite unlike those after ergot but closely resemble those after atropine. It is concluded that it is unjustified to assume that drugs produce similar effects in fishes and in mammals. The case for double innervation of melanophores is therefore still unproven.
Nervous Control of Chromatophores in Teleost Fishes
Authors: Pye J. D.
Published: April 2021

The rate of chromatic adaptation to background colour has been examined briefly in thirty-three species of teleost fishes (from nineteen families, eight orders) to test the presence of nervous control of chromatophores. The same fishes have then been tested for chromatic responses to local heating or cooling of the skin. Thermal responses resembling those of Phoxinus have been found in fourteen species which show quick adaptation, but not in thirteen other such species. No thermal responses have been found in any of the six species which do not show quick adaptation. There appears to be no significance in the taxonomic distribution of these results and no new responses to temperature have been found.
Electrophysiological Investigations of the Heart of Squilla Mantis
Authors: Brown Hilary F.
Published: April 2021

With an external hook electrode placed upon the ganglionic nerve trunk of the isolated heart of Squilla mantis a burst of a small number (3-12) of nerve impulses was recorded at each heart beat. The number of impulses per burst showed a direct correlation with interval between bursts. The only consistent feature of impulse pattern within the bursts was a lengthening of the intervals between impulses towards the ends of the bursts. Electrodes at two points on the ganglionic nerve trunk each recorded the same number of impulses at a burst. The delay between the two recording points was the same for all impulses, and usually all the impulses were, in a given heart, recorded travelling in the same direction, though this could be either forwards or backwards along the chain. It is suggested that each cell in the chain of 16 fires in succession the same number of times during a burst and that the impulses travel along the same ‘firing channel’ within the ganglionic nerve trunk. Cells near the two ends of the chain showed the greatest spontaneity when isolated by transverse cuts or ligatures. Coupled with the records obtained from two points, this suggests that the bursts are initiated in the front or back regions of the chain, but not invariably by the same one of the 16 cells.
Electrophysiological Investigations of the Heart of Squilla Mantis
Authors: Brown Hilary F.
Published: April 2021

The histology of the heart muscle of Squilla mantis is briefly described. Vital staining with methylene blue revealed only a sparse distribution of nerve endings on the muscle network. Intracellular electrodes recorded from the muscle a multi-peaked junction potential at each heart beat. Each peak followed an impulse in the ganglionic nerve trunk burst. All the peaks were approximately the same height and none more than about three-fifths the height of the resting potential (average values for 10 hearts: resting potential, 51·5 mV; junction potential, 27·6 mV). Inverted (negative-going) signals were never recorded just outside the muscle membrane suggesting that at all the points which were searched the membrane was acting passively. Driving Squilla heart muscle via its nerve supply at too stimuli per second did not depolarize it by more than about 35 mV, nor would depolarizing pulses given directly to a fibre through an intracellular electrode set up any sort of current-generating activity in the membrane. The magnitude of muscle contraction, measured locally using a microelectrode transducer, depended on the absolute level of the potential across the membrane, rather than on change of potential. A directly applied electrotonus, similar in magnitude and duration to the nerve-induced junction potential, caused a local contraction of similar magnitude. The recorded junction potential is therefore interpreted as the composite record of the electrotonus spreading within the muscle network from current initiated at relatively infrequent active points on the muscle membrane (the nerve endings) which passively depolarizes the rest of the membrane. The junction potentials showed facilitation when the intervals between them were below 4 sec. At intervals less than 630 msec, they summed.
The Swimming Response of the Sea Anemone Stomphia Coccinea to Electrical Stimulation
Authors: Ross D. M. , Sutton L.
Published: April 2021

The swimming response of Stomphia coccinea evoked by electrical stimuli has been re-examined. Contrary to earlier accounts, definite relationships have been discovered between the occurrence of swimming and the number, frequency and intensity of electrical stimuli applied. At higher frequencies (1 stimulus/0·4 sec.), 4·6 stimuli cause swimming; at lower frequencies (1 stimulus/3·0 sec.), 24−40 stimuli are needed to produce the same effect. Stronger stimuli are required to evoke the swimming response than to cause the retraction response. At constant durations, the threshold for swimming is at least 50% above the voltage required for retraction; at constant voltage, the threshold duration of pulses that give swimming is at least three times the duration of pulses that cause retraction. It is concluded that retraction and swimming are controlled by different excitation systems. The system controlling swimming has a higher threshold and it is not an all-or-nothing process. The results are discussed in relation to facilitation of the swimming response and some behaviour patterns in another sea anemone, Calliactis parasitica.
Inhibition of the Swimming Response by Food and of Nematocyst Discharge During Swimming in the Sea Anemone Stomphia Coccinea
Authors: Ross D. M. , Sutton L.
Published: April 2021

The discharge of tentacular nematocysts in response to food was studied in Stomphia coccinea before and during swimming, and during the period of resettling. The tendency of Stomphia’?, nematocysts to discharge on contact with food virtually disappeared during the swimming response. The disappearance of the nematocyst response coincided with the release of the pedal disk; its reappearance coincided with the re-attachment of the pedal disk. Objects rubbed on the aboral surface of Dermasterias can cause swimming if brought into contact with a single tentacle of Stomphia. A general inhibition of the swimming response to objects rubbed on Dermasterias was set up by flooding the tentacular crown with a food extract. A local inhibition was set up when food was applied to a single tentacle just before the same tentacle was touched with material from Dermasterias. The results are discussed in relation to the view that nematocysts function as independent effectors.
Blood Volumes, Blood Distribution and Sea-Water Spaces in Relation to Expansion and Retraction of the Foot inBullia(Gastropoda)
Authors: Brown A. C.
Published: April 2021

The expansion and retraction of the foot has been studied in the prosobranchiate sandy-beach gastropod, Bullia. In Bullia the foot is capable of an unusually great expansion, but this is not dependent upon an unusually large volume of blood. Radiographical investigations have shown that on retraction blood flows direct from the pedal sinus to the visceral sinus system without passing through the heart, kidney or gill. Investigation of the jets of water produced on retraction has shown that in the expanded animal the visceral region within the shell is surrounded by sea water. The roles of blood movement and of contraction of the columella muscle, and also various other aspects of the circulation, are discussed.
Black and White Preferences in the Frog, Rana Temporaria, and Other Anura
Authors: Boycott B. B. , Mrosovsky N. , Muntz W. R. A.
Published: April 2021

Conditions are described in which the frog, Rana temporaria, selects the darker of two stimuli. Some similar observations are reported for other amphibians. Further experiments suggested that a dark starting area is a factor tending to decrease negative phototaxis. Forcing the frogs from the dark starting area decreased the scores for the darker of two stimuli. No strong positive phototaxis was found in the present experiments. In conditions giving negative phototaxis there is a slight preference for blue over green. These results are compared to previous work and discussed in relation to the possible underlying mechanism and their biological value.
Some Preliminary Observations on the Effects of Cations on Conduction Processes in the Abdominal Nerve Cord of The Stick Insect, Carausius Morosus
Authors: Treherne J. E.
Published: April 2021

In the haemolymph of the stick insect Carausius morosus the concentration of potassium exceeds that of sodium and the concentration of magnesium exceeds that of calcium. The implications of this situation for nerve conduction have been studied. Conduction is maintained in intact and desheathed preparations of the fourth adbominal ganglion under irrigation with a solution resembling haemolymph in ionic composition. Action potentials recorded in response to electrical stimulation of the nerve cord decline in sodium-free solutions, both in intact and in desheathed preparations. Conduction declines slowly under irrigation with magnesium-free solutions both in intact and in desheathed preparations.
The Motion of Strigomonas Oncopelti
Authors: Holwill M. E. J.
Published: April 2021

The movement of the flagellum of Strigomonas oncopelti has been studied using high-speed cinephotography. Waves usually pass along the flagellum from tip to base but under certain conditions waves are propagated from base to tip, reversing the direction of movement of the organism. Increasing the viscosity of the medium reduces the frequency of beat while the shape of the wave remains unaltered. The variations in the wave parameters with increasing viscosity are consistent with a mechanically propagated wave. Calculated values for Young’s modulus indicate that the membrane, the matrix, the nine peripheral fibrils or the central pair could act as the compressive elements needed to resist bending. The mechanism controlling the direction of wave propagation appears to lie in the membrane.
Three Parallel Conducting Systems in the Stalk of A Hydroid
Authors: Josephson Robert K.
Published: April 2021

There are three, non-polarized conducting systems in the stalk of Tubularia. These are termed the distal opener system (DOS), the triggering system (TS), and the slow system (SS). The DOS controls opening of the distal tentacles of the hydranth. Activation of the DOS produces a small electric pulse in the stalk which is conducted at about 15 cm./sec. At the base of the distal tentacles this pulse is followed by a slow potential. The slow potential but not the pulse shows antifacilitation and is quickly blocked by excess Mg2+, as are distal tentacle movements. This is taken to indicate that the pulse and slow potential are a result of nerve and muscle activity respectively. The TS can trigger the potentials which normally appear spontaneously in the neck region of the hydranth. The TS conducts at about 17 cm./sec and has a lower threshold than the DOS. No electrical correlate of TS activity has been found. Activation of the SS produces large (up to 1 mV.), slowly propagated (about 6 cm./sec.) potentials in the stalk. The SS is very labile. In a fresh animal the SS threshold is two to three times that of the DOS and the SS often fires repetitively to stimuli above its threshold. SS activity has apparently no effect on polyp behaviour or on spontaneous electrical activity in the hydranth.
Studies on the Chemical Composition of Muscle Tissue
Authors: Robertson James D.
Published: April 2021

Mantle muscle from Sepia officinalis, Loligo forbesi and Eledone cirrhosa has been analysed for all the major constituents contributing to its osmotic concentration, including inorganic ions, organic phosphates, amino acids and nitrogenous bases. Intracellular concentrations have been calculated for Sepia and Eledone muscle after appropriate corrections for extracellular fluid as measured by inulin space. From analyses of the juice pressed from muscle it has been concluded that the whole of the cell calcium, much of the magnesium and sodium, and a lesser proportion of potassium is bound to cell constituents ; the chloride ion is completely free. Direct measurements of the osmotic concentration of muscle-juice and plasma of Eledone show that the juice is slightly hyperosmotic (+ 3·2% on plasma value), probably owing to some breakdown of labile compounds. The ions and compounds studied make up 94% of the osmotic concentration of the muscle cells in Sepia, and 86 % in Eledone. Over half of the osmotic concentration of the cells is made up by free amino acids, trimethylamine oxide and betaine.