bluuebunny/crossref_metadata_2025 huggingface dataset:
Ciliary Activity and Oxygen Uptake in Branchiostoma Lanceolatum (Pallas)
Authors: Courtney W. A. M. , Newell R. C.
Published: April 2021

The rate of oxygen uptake by single specimens of Branchiostoma lanceolatum has been shown to vary considerably. Some animals in sealed vessels at 15 ° C. were able to utilize the oxygen linearly down to less than 20% of air saturation. Others ceased to absorb oxygen at high saturations while yet others displayed two different rates in a sequence starting initially with a high rate. There are three possible rates of oxygen utilization, as well as a zero rate, for an animal at any temperature between 10 and 19 ° C. Animals in gravel exhibit only two rates at lower temperatures. The slowest rate varies exponentially with temperature but the two faster rates show a rapid increase between 10 and 15 ° C. with little change outside this temperature range. The effect of size and temperature on the increased oxygen uptake during the faster rates of respiration are discussed. It is suggested that ciliary activity of the pharynx could be associated with the extra oxygen utilization. It has been found that there are three inhalant stream velocities, a fast, a slow and a zero rate with no intermediate rates. Study of the isolated portions of the pharyngeal wall confirm that the fast inhalant current is set by the activity of all the cilia to give a feeding stream. The slow stream is set up by the lateral cilia, which continue to beat when the frontal cilia and most of the lateral cilia have been inhibited by lowered oxygen concentrations. The lateral cilia have been shown to be under nervous control and to be inhibited by pressure on the pharyngeal bars. This mechanism depends on the presence of a connexion between the pharyngeal bars and the endostyle.
The Signal Generated by An Insect in A Spider’s Web
Authors: Parry D. A.
Published: April 2021

There is evidence that web-spinning spiders discriminate between prey and artifacts in their webs, and that the signal involved is a mechanical one. As a con tribution to our understanding of the basis of this discrimination, an analysis has been made of the natural signal generated by an insect in the web of the British house spider Tegenaria atrica. The signal investigated was frequency-limited to 1 kc./sec., this being the upper limit of the linear response of the specially designed transducer. The signal has an irregular wave-form with most of the energy lying below 50 cyc./sec. Damped transverse and rotational oscillations of the mass of the spider in the compliance of the web have been recognized. In addition there are ‘fast transients ‘, most likely due to the sudden release of tension in the web by slight movements of the insect. The possibility that the fast transients form the basis of prey-recognition is being investigated.
Osmotic and Ionic Regulation in the Prosobranch Gastropod Mollusc, Viviparus Viviparus Linn
Authors: Little C.
Published: April 2021

Investigations of the composition of the blood and tissues of freshwater invertebrates, and the relations that these bear to the composition of the external medium, have in the main been confined to crustaceans and insect larvae, whilst the molluscs have been somewhat neglected. Potts (1954, 1958) and Florkin & Duchâteau (1950a) have studied the lamellibranch Anodonta cygnaea in some detail. Duval & Portier (1927) and Florkin & Duchâteau (1950b) have given some figures for the pulmonate Limnaea stagnate. Among the prosobranchs, published work appears to provide nothing more than values for the depression of freezing-point of the blood of Viviparus viviparus (Fredericq, 1904), V. fasciatus (Obuchowicz, 1958), and Theodoxus fluviatilis (Neumann, 1960).
Nerve Impulse Patterns and Reflex Control in the Motor System of the Crayfish Claw
Authors: Wilson D. M. , Davis W. J.
Published: April 2021

The opener muscle of the crayfish claw receives, under nearly natural conditions, a train of excitatory nerve impulses which may show a temporal patterning to which the muscle is specially sensitive. Especially at high frequencies the impulse train contains doublets which form a separate class in the interval distribution. Their appearance at high frequencies gives rise to an increase in the coefficient of variation of interval lengths. Excitatory and inhibitory motor neurons to the same opener muscle seem to be part of the same commonly excited motor neuron pool. Frequency changes in the two axons generally show positive correlations. For most inputs and for ‘spontaneous’ central drive the excitor has the lowest threshold and shortest latency, and it gives the earliest indication of changes of excitatory state. Proprioceptive input from the claw may excite both motor neurons, but generally the inhibitory one gives the earlier, bigger response. The peripheral inhibition completes a negative feedback loop. Inhibitory frequencies plotted against concurrent excitatory frequencies give points falling into two groups with different slopes dependent upon input source. For general body inputs the slope is less than one and for proprioceptive claw input it is much more than one. This divergence leads to greater effectiveness of either excitation or inhibition as overall level of output increases, with a good separation of antagonistic functions in spite of the apparent lack of reciprocal interaction.
Reflex Control of Abdominal Flexor Muscles in the Crayfish
Authors: Kennedy Donald , Takeda Kimihisa
Published: April 2021

In the crayfish abdomen most of the power for the flexor twitches employed in swimming is supplied by the massive oblique muscles which are innervated by large motor axons from the third root. All of the delicate flexor control of the abdomen is vested in a thin, superficial sheet of muscle fibres which have the histological characteristics of ‘slow’ muscle and are innervated by a special, independent supply of small motor nerves (Kennedy & Takeda, 1965). These forty or so muscle fibres and half-dozen axons comprise a reflex apparatus of exquisite complexity, both with respect to innervation pattern (which ranges from single to sextuple for single muscle fibres) and to central modulation of efferent discharge.
Multiple Pacemakers and the Behaviour of the HydroidTubularia
Authors: Josephson R. K. , Mackie G. O.
Published: April 2021

The spontaneous behaviour of the hydroid Tubularia results from the activity of a number of pacemaker systems in the polyp, there being a major pacemaker system in the distal stalk (the NP system), another in the hydranth body (the HP system) and individual pacemakers in each of the tentacles. The NP system produces single electrical pulses and bursts of three or more pulses, the HP system itself produces single pulses and short bursts of 2-4 pulses, and the tentacle pacemakers fire irregularly. The HP and NP systems are mutually interactive. When the NP system fires in a burst it usually drives the HP system to fire concurrently. Single firing by the NP system sometimes triggers the HP system to fire, and single HP firing can trigger the NP system. Single HP firing is most likely to trigger the NP system if it comes long after the last NP firing, i.e. late in the NP spontaneous cycle. When the HP system independently fires a burst or is driven by the NP system to fire a burst, it drives pacemaker systems in the proximal tentacles to fire concurrently. Firing of the HP system is associated with a behavioural response termed a concert. During a concert the proximal and sometimes the distal tentacles are synchronously elevated. During the longer NP-HP bursts the neck contracts. A peristaltic wave sweeps down the proboscis following the tentacle elevation. Concerts without neck contraction result in mixing of fluid in the enteron chamber of the proboscis ; concerts with neck contraction result in tidal exchange of fluid between the neck chamber and the proboscis chamber. Stimulation of the conducting system in the stalk termed the triggering system (TS) can trigger the NP system to fire. A stalk stimulus is most likely to trigger the NP system if it comes within a few seconds of NP firing, i.e. early in the NP spontaneous cycle. Firing of the NP system of one polyp in a colony can trigger the NP systems of connected polyps. Interpolyp triggering is probably mediated through the TS conducting system. The coupling between NP systems of connected polyps results in synchronization of NP bursts throughout a colony. Because of the coupling between NP and HP systems within single polyps the longer HP bursts, which are those occurring when the HP system is driven by the NP system, are also usually synchronous in connected polyps. This results in concerts with neck contraction being nearly synchronous throughout a colony. Such synchronization facilitates transfer of fluid between the two enteron chambers of polyps during concerts. Prolonged, low-frequency stalk stimulation inhibits spontaneous activity of a polyp, the inhibition increasing with increasing stimulus frequency. The large size of the spontaneous electrical pulses suggests that they are not the result of nervous activity, but possibly due to activity of more primitive co-ordinating mechanisms.
Proprioceptive Leg Reflexes in Cockroaches
Authors: Wilson Donald M.
Published: April 2021

Proprioceptive feedback from the moving wings of locusts contains information which could be sufficient for the control of the timing of the wing-muscle contractions. It has been found, however, that at the high frequency of limb movement used in flight this phasic information content is lost in the ganglionic transfer (Wilson & Gettrup, 1963). During rapid running the legs of cockroaches also oscillate at high frequencies, sometimes as rapidly as wing movements of similar-sized animals. It is therefore necessary to know whether the frequency response capabilities of the leg reflexes are similar to or different from those of the wings in order to understand how the legs are coordinated. If the leg reflexes are limited to the same range as that available to the wing reflexes, then coordination of the legs would necessarily depend upon ganglionic phasing mechanisms ; that is, the elementary pattern of leg movements could be due to central nervous control alone, as is true of the locust wing control (Wilson, 1961). However, it can be shown that the phasic leg reflexes are capable of operation at frequencies even greater than those encountered in running. Apparently the significant limitation on rate of leg movement is not nervous but mechanical; that is, due to the maximum rate of contraction of the muscles.
Measurements of the Oxygen Tension in the Lumen of the Small Intestine of the Domestic Duck
Authors: Crompton D. W. T. , Shrimpton D. H. , Silver I. A.
Published: April 2021

By use of an oxygen electrode measurements of oxygen tension have been made in the lumen of the small intestine of the domestic duck in the region occupied by the acanthocephalan parasite, Polymorphus minutus. The tension was found to vary from 25 mm. Hg close to the villi to less than 0·5 mm. Hg in the centre of the lumen.
Co-Ordination of Successive Activities in an Aphid. Reciprocal Effects of Settling on Flight
Authors: Kennedy J. S.
Published: April 2021

Individual aphids were allowed to fly for set periods, to land on a host leaf, a non-host leaf or a card and make settling responses to it, and then to take off again, without handling, in a laboratory flight-chamber with continuous recording of the rate of climb as a measure of flight activity. The after-effect of a landing was typically a boosting or rebound of flight, which was sometimes accompanied within seconds by depression of it. The boosting effect of landings summated, and the depressing effect waned, through a series of 1 min. flights. Both effects were greater after landings on a leaf than after landings on a card, where the settling responses were weak and flight was therefore inhibited only briefly. Normally the depressing after-effect was greatest with landings on the host leaf, where the settling responses were strongest and flight was inhibited the longest. When flight had been brought up to a highly excited state by previous landings, a landing on the host had little or no depressing after-effect upon flight and now boosted it more than landings on a non-host leaf or card. The strength of the flying aphids’ phototactic response in the horizontal (yawing) plane varied with the strength of their photokinetic response measured as the rate of climb. The results effectively precluded the possibility of flight rebound being due to the rest gained while settled ; they support the conclusion that both the rebound and the depression of flight following a landing are after-effects of the temporary inhibition of flight by the settling responses. These two after-effects of settling on flight duplicate the reciprocal after-effects of flight on settling described previously as antagonistic induction and antagonistic depression. Both appear to depend on central nervous interaction rather than peripheral feedback.
Sensory Regulation of Wing Twisting in Locusts
Authors: Gettrup Erik
Published: April 2021

The campaniform sensilla of the wings are necessary for the regulation of wing twisting in locusts. Control of forewing twisting during periods of constant lift depends upon the hind-wing sensilla being intact, whereas the forewing sensilla are essential for stability about the three body axes. The campaniform sensilla are located on the ventral surface of the wings. Two groups are present on the subcosta of the forewing and one on the subcosta of the hindwing. A few single sensilla occur on the costa. The cuticular parts of sensilla from distal and proximal forewing groups differ with respect to the lengths of their ovally shaped cuticular parts. The sensilla are orientated with the cupolas parallel to the long axis of the wing, except for those of the proximal forewing group, which are arranged in a fan. During steady-state flights activity from campaniform units was high during the downstroke and low during the first part of the upstroke. Significant changes in the response were found to occur when the body angle was changed. The effect of a 15° change in body angle on the motor output to the basalar and subalar muscles is described. At the start of a flight these motor patterns are rather unstable, units falling in and out. Stability is gained within 10 sec. A distinct part of the response from the campaniform units in the hindwings can be abolished by the application of an anodic block. The duration of the blocking pulse equalled one-sixth of the flight period. The effect on regulation of forewing twisting varied according to the part of the response which is removed. Regulation could be abolished almost completely when the anodic block was introduced during the first part of the hindwing downstroke. When the anodic block is removed, twist regulation builds up again and is completed within 100-150 wing-beats. Free flights including both intact and deafferentated animals made possible an evaluation of the importance of the different groups in stability reactions. It was shown that control of angular movement is accomplished by the forewing groups only, especially the proximal ones. The integrative processes within the pterothoracic ganglia are discussed. During the constant-lift reaction, the slow, intersegmental reflex for control of forewing twisting seems to depend on central processing and memorizing of measurements of total lift. The sensory input from the hindwings is phasic and patterned, but it is still undecided whether it is the phase or the pattern which is the essential parameter.
Rubber-Like Properties of the Inner Hinge-Ligament of Pectinidae
Authors: Alexander R. McN.
Published: April 2021

The inner hinge-ligament of Pectinidae (Lamellibranchiata) is an elastic block of amorphous cross-linked protein, plasticized with water. It acts as a compression spring, and is the antagonist of the shell adductor muscle. Its elasticity is shown to be rubber-like, in that the elastic restoring force is mainly due to entropy changes. Rubber-like elasticity has been demonstrated by other authors in two other proteins (elastin and resilin). Pectinidae swim by rapid opening and closing of the shell. The resilience of the inner hinge-ligament of Chlamys at the frequency of the swimming movements is at least 91%. The inner hinge-ligament of Pectinidae is compared with other proteins which show long-range elasticity.
Aspects of the Neurophysiology of Buccinum Undatum L. (Gastropoda)
Authors: Bailey D. F. , Laverack M. S.
Published: April 2021

Recordings have been made from various central neurones of Buccinum undatum, the common whelk, particularly in response to peripheral stimulation of the osphradium. These central responses show that the osphradium is sensitive to the application of a restricted range of chemical stimuli, but insensitive to mechanical stimulation with suspended particulate matter. The most pronounced central activity was seen in response to the addition of a sea-water extract of Mytilus edulis. This animal is one normally preyed upon by Buccinum. The synthetic chemicals most closely mimicking this effect were glutamic and aspartic acids, which were effective at low-threshold concentrations. Other chemicals of 4-6 carbon-atom chains with terminal carboxyl groups were effective stimuli and it therefore appears that the dicarboxylic nature of the effective amino acids plays a major part in the stimulatory process. Intracellular recordings indicate that the peripheral input from osphradial chemoreceptors and mantle mechanoreceptors may be either excitatory, inhibitory or without effect on central neurones.

This work was carried out whilst one of the authors (D.F.B.) held a D.S.I.R. Studentship. Part of the equipment was obtained on a Royal Society Grant-in-Aid to M.S.L.
A Lepidopteran Saline: Effects of Inorganic Cation Concentrations On Sensory, Reflex and Motor Responses in A Herbivorous Insect
Authors: Weevers R. De G.
Published: April 2021

The inorganic cations in the haemolymph of Antheræa pernyi larvae and pupae were analysed by flame photometry. Synthetic media based on these analyses were compared with haemolymph in their effects on the muscle action potential and on the response of the dorsal muscle receptors to a standard stretch. The best match with haemolymph was obtained in all cases with concentrations of divalent cations considerably below the values found by flame photometric analysis. Binding to haemolymph proteins is probably not the major factor responsible for lowering the ionic activities of calcium and magnesium. The role of magnesium in neuromuscular transmission is discussed. It is concluded that in phytophagous Lepidoptera this ion may carry a proportion of the muscle action current.

I am grateful to my supervisor, Prof. G. M. Hughes, for guidance and encouragement during this work, and to the D.S.I.R. for financial support in the form of a research studentship.
The Physiology of A Lepidopteran Muscle Receptor
Authors: Weevers R. De G.
Published: April 2021

The afferent discharge from the lepidopteran MRO provides complex information to the c.N.s. on the parameters of movements occurring at the periphery. Not only ‘position’ but also ‘movement’ and ‘acceleration’ components are present in the response. While the position response is very nearly linearly related to the length of the receptor, the movement response is related to the square root of the rate of stretch. The acceleration response bears a more more complex relation to the stimulus. The responses of the sense organ to stretching are discussed in relation to the possibility of using methods of linear systems analysis. The observed non-linearities preclude such treatment of the present data.

I am very grateful to my supervisor, Prof. G. M. Hughes, for guidance and encouragement during this work, and to the D.S.I.R. for financial support in the form of a research studentship. I am also indebted to Dr R. H. J. Brown for the basic design of the stretcher.
The Permeability to Water of the Cuticles of Some Adult Water Bugs
Authors: Staddon B. W.
Published: April 2021

The permeability to water of the cuticles of some adult water bugs has been measured using deuterium oxide (heavy water) as tracer. The D2O permeability constant of Ilyocoris cimicoides cuticle was 1-7 × 10-2 cm./hr. at 18° C. There was no apparent difference between the rates of D2O influx and efflux at 18° C., but at 28° C. a possible difference between them was indicated. The Q10 of the influx was 1·8 over the temperature interval 8-18° C., 1·5 over the interval 18-28° C. The estimated osmotic water uptake was 2·3% of the body weight per day at 18° C. In Corixa dentipes adults the D2O permeability constant of the cuticle was 2·3 × 10-2 cm./hr. at 18° C. and the derived osmotic water uptake 3% of the body weight per day. In Notonecta glauca adults the corresponding values were 1·4 × 10-2 cm./hr. and 1·8% of the body weight per day.
Oxygen Transport by the Circulatory System of the Green Iguana (Iguana Iguana) at Different Body Temperatures
Authors: Tucker Vance A.
Published: April 2021

Oxygen consumption, stroke volume, heart rate and the difference in oxygen contents of arterial and venous blood (AV difference) were measured in the resting iguana at body temperatures of 20, 30 and 38° C. Oxygen consumption increased by a factor of 4·4 as temperature changed from 20 to 38° C. This increase was accomplished by a decrease in stroke volume by a factor of 0·5, and increases in heart rate and A V difference by factors of 4-1 and 2-2, respectively. During activity increases in oxygen consumption at a given temperature were accompanied by increases in heart rate and A V difference, but stroke volume did not change consistently. The percentage saturation of arterial blood with oxygen in the iguana may differ in the right and left systemic arches. In some lizards, both arches carried equally saturated blood, but in others the left arch carried blood containing less oxygen than the right arch. An hypothesis is presented concerning the function of the double systemic arches and incompletely divided ventricles of lizards. These structures may be a device for permitting increased cardiac output associated with thermoregulation to bypass the lungs while maintaining a supply of well-oxygenated blood to the head. Data on oxygen capacity, percentage saturation of blood with oxygen, haematocrit and pH of iguana blood are included in this study. This study was supported by a National Science Foundation Postdoctoral Fellowship. I am indebted to Prof. W. R. Dawson, who provided laboratory facilities and advice to make this study possible.
The Hormonal Control of Colleterial Gland Secretion
Authors: Willis J. H. , Brunet P. C. J.
Published: April 2021

Methods for the quantitative assay of the activities of the left and right colleterial glands of adult cockroaches (Periplaneta americana’) are reported. The former involves the spectrophotometric measurement of the content of protocatechuic acid glucoside of the gland ; the latter the measurement of glucosidase activity by orthodox use of a chromogenic substrate. Glucoside and glucosidase have been studied in terms of accumulation and turnover. The accumulation of the glucoside requires the presence of active corpora allata, but glucosidase synthesis is seemingly independent of this.
The Excretory Role of Pteridines in Insects
Authors: Harmsen R.
Published: April 2021

Previous work on the storage excretion theory of pteridines is summarized briefly, and the controversial aspects of this theory are discussed. A general model for all nitrogen-containing substances in an animal body is presented. The possible pathways for pteridines in this model are discussed, and the storage excretion hypothesis is related to the model. Storage and excretion of nitrogen-containing substances in Pieris brassicae were compared chromatographically on a quantitative basis. Only traces of the pteridines are excreted, the majority being stored, mostly in the adult cuticular scales. Only 20% of the uric acid is excreted; the xanthine is quantitatively stored in the fatbody. Removal of part of the wing storage potential increases excretion and fatbody storage only very slightly. There is a reduction in overall pteridine synthesis. A partly scaleless mutant, cerula, of P. brassicae also shows a slight increase in pteridine excretion coupled with an overall decrease in pteridine synthesis. Vanessa io, a related species not containing large quantities of pteridines, was closely compared with P. brassicae. In Vanessa nearly half the pupal pteridines are excreted with the meconium, and no storage is found in the cuticular scales. Several insects of other orders were investigated quantitatively. Only in some Hemiptera were pteridines found, stored in quantities comparable to those in Pieridae. Using an ultra-micro Kjeldahl technique for total soluble nitrogen, the relative role of purines, pteridines, and some other minor substances, both in storage and excretion, was established. It is obvious that in Pieridae the pteridines account for a much higher percentage of the total highly oxidized nitrogen produced (14%) than they account for in most other insects. The Pieridae differ further in storing most of these pteridines irreversibly in the cuticular scales of the adult. The evidence strongly suggests that the Pieridae have evolved a metabolic mechanism of which pteridines are the general end-product as well as a mechanism of dry storage excretion for these end-products. The pigmentation effect of cuticular pteridine deposition is considered a sideeffect.
Activity in the Optic Nerve of Pecten Maximus in Response to Changes in Light Intensity, and To Pattern and Movement in the Optical Environment
Authors: Land M. F.
Published: April 2021

In the eye of Pecten maximus there are two functionally independent retinae. The proximal retina contains receptors which respond to increase of illumination, those of the distal retina respond to decrease. The activity of each retina was investigated by recording from the optic nerve, which contains the axons of both types of receptor. Visual stimuli used included changes in overall illumination, pattern and movement. Dark adaptation was also studied. The ‘off’ response is generated by cells which are anatomically primary receptors. Two light dependent processes are involved: a slow development of excitability and a simultaneous inhibition of action potentials. The reflected image is important in movement perception. Only the distal cells lie in the image plane, and they can respond to moving objects, as these cause dimming of successive cells when their images cross the retina. Dark objects subtending 2° or more at the eye, and moving through more than 2°, are effective stimuli. Light objects are also effective, provided they have remained stationary for several seconds before moving. There is no response to stationary pattern. The proximal cells respond only to increase in overall light intensity. These findings are discussed in relation to the behaviour of Pecten.
The Proboscis Mechanism of Acanthocephalus Ranae
Authors: Hammond R. A.
Published: April 2021

Comparatively little is known of the activities and physiology of the Acanthocephala, despite the fact that these animals embody a number of unique structural features of great interest
Neuromuscular Transmission in A Sea Anemone
Authors: Josephson Robert K.
Published: April 2021

Brief electrical potentials can be recorded from a suction electrode over the marginal sphincter or over a tentacle of the anemone Calliactis polypus following appropriate stimulation of the anemone. These potentials are thought to be muscle action potentials because they precede contraction by about 12 msec. (29−31° C.) and their size is smoothly graded with the size of the contraction. The tentacles and sphincter are activated by a through-conducting system in the oral disk and column. As with other anemones studied, two stimuli are required to evoke sphincter contraction. The maximum interval between an effective pair of stimuli is about 600 msec, and the sphincter potential and contraction increase with decreasing intervals to a minimum interval (as short as 15 msec.) below which there is no response to the second shock. Tentacles behave similarly except that they often produce small potentials and sometimes tiny contractions to single stimuli. During repetitive stimulation the muscle potentials facilitate and the individual contractions both facilitate and sum. The tentacle musculature becomes maximally active earlier in a stimulus burst than does the sphincter.
Sound Production and Reception In A Cockroach
Authors: Guthrie D. M.
Published: April 2021

The cockroach Henschoutedenia epilamproides produces distinctive patterns of sound, on being disturbed, by means of a stridulatory apparatus. The carrier frequency of the sound is between 4·5 and 5·0 kcyc./sec., and is amplitude-modulated to form pulses. These pulses are grouped to form chirps, which are emitted singly or in a series. The structure of the longer chirps (50−100 msec.) may be quite complex. While the circumstances under which sound is usually produced in the laboratory suggests that it is not important in intraspecific communication, it may be of some importance to the cockroach to hear its own sound. Recordings made from the cereal nerve show that the cockroach responds hardly at all to its own sound, and very poorly to artificial tones above 400 eye./sec. The cereal afferents are most sensitive to tones of 50 eye./sec., and will respond to less than 60 db. at this frequency. Although the auditory performance of Henschoutedenia cereal receptors appears poor by comparison with Periplaneta americana, their responses to air movements are most striking. Some difficulty was experienced in standardizing this form of stimulation, but it appeared that Henschoutedenia was much more sensitive than Periplaneta to this form of stimulation. Experiments with rodents (Rattus rattus and Clethrionomys glareolus) lent some support to the idea that the cockroach sound mimicked the cries of rodent predators, and had some deterrent effect on them.
Neuromuscular Mechanisms of Burrow Irrigation in the Echiuroid Worm Urechis Caupo Fisher & Macginitie
Authors: Lawry James V.
Published: April 2021

The anatomy of the muscular and nervous systems of Urechis is described. An apparatus is described whereby it is possible to record the parameters of the peristaltic waves used in irrigating the tube. Urechis is continuously active and shows no periodicity under conditions of constant temperature. About 1280 peristaltic waves are initiated, and about 29 L of water are moved, in 24 hr.
The fluid dynamics of the bivalve molluscs, Mya and Margaritifera
Authors: Trueman E. R.
Published: April 2021

A comparison is made of the fluid dynamics of a shallow, yet actively, burrowing bivalve, Margaritifera, with the sessile, deeply buried Mya armaria. In both adduction produces high pressures (up to 100 cm.) in the mantle and the pericardial cavities which are utilized in Margaritifera for locomotory purposes, in Mya principally for siphonal extension. With siphonal and pedal apertures closed the mantle cavity of Mya is virtually watertight and acts, together with the blood, as the fluid of an antagonistic muscle system, whereby adduction causes siphonal extension and siphonal retraction pro­duces an increase in gape of the valves. The close interaction between these two muscle systems is illustrated by pressure recordings of Mya in the normal buried position. Siphonal movements are shown to be associated with divarication of the valves and accompanying pressure changes. Consideration is given to the haemodynamics of Mya and by contrast with the high pressures involved in locomotion or siphonal movement, maximum pressures of only 2-5 cm. were recorded from the heart, producing a sluggish circulation. The higher pressures derived from the body musculature make an important contribution to movements of the blood.
Permeability of the Abdominal Nerve Cord of the American Cockroach, Periplaneta Americana L. to Quaternary Ammonium Salts
Authors: Eldefrawi M. E. , O’Brien R. D.
Published: April 2021

The influx and efflux of two series of quaternary alkylammonium cations in the abdominal nerve cord of the American cockroach have been studied. The data are interpreted as showing that increasing liposolubility tends to increase penetration, and increasing size (with respect to the smallest cross-sectional area) decreases it. The influx rates of the quaternary alkylammonium cations into the cockroach central nervous system (C.N.S.) is 2-7 times lower than Na+ when equimolar concentrations are compared. Acetylcholine penetrates into the C.N.S. rapidly due to its metabolism, since in the presence of eserine its influx rate becomes similar to that of the analogous alkylammonium cation which is unmetabolized. The alkylammonium cations that penetrate into the C.N.S. appear to be distributed into fast and slow pools, as judged by their relative rates of efflux. These may represent the distribution of cations between extracellular and intracellular spaces or possibly free and bound cations in the extracellular spaces. Although the alkylammonium cations penetrate the C.N.S., they apparently encounter a regulatory system that discriminates against large size, positive charge and polarity. This research project was financed in part by NIH Grant GM 07804-06.
Studies on the Effects of the Removal of the Frontal Ganglion in Locusta Migratoria L
Authors: Clarke Kenneth U. , Gillott Cedric
Published: April 2021

Studies were made on the third, fourth-, and fifth-instar nymphs of Locusta migratoria L. from which the frontal ganglion had been removed, on controloperated animals, and on starved animals. The effects of this operation on protein metabolism were observed by study of: electrophoresis of haemolymph proteins, chromatography of haemolymph amino acids, production of protease in the midgut, and the incorporation of 14C-glycine into protein by the body cells. The total protein concentration in the haemolymph of operated locusts did not increase with time as did that of the controls, in which the increase was almost entirely due to changes in the second of the three bands which normally separate out. The concentration of the free amino acids in the haemolymph fell to about 70% of that found in the operated controls. In operated locusts the proportions of the amino acids relative to one another changed. The incorporation of 14C-glycine into protein was slower and the equilibrium concentration less in operated as compared with control-operated animals. The time taken to reach equilibrium was the same in both cases. In both operated and control-operated animals the protease activity of the midgut wall was very low; no difference could be detected between them. The protease activity of the mid-gut contents expressed per mid-gut was lower in operated than in control-operated animals. The protease activity expressed per mg. was found to be the same in operated, control-operated and starved animals. The hypothesis that the effects of the removal of the frontal ganglion were mediated through changes in the secretion of hormones from the corpus cardiacum was tested by giving daily injections of freshly prepared corpus cardiacum extract to locusts from which the frontal ganglion had been removed, and observing the growth in weight of these animals. A permanent increase in weight amounting to 100% of their initial weight was found. Animals injected with distilled water showed a temporary increase amounting to 30% of their initial weight. Uninjected animals maintained approximately constant weight.
Giant Neurons and Axon Pathways in the Brain of Tritonia
Authors: Dorsett D. A.
Published: April 2021

The anatomy and histology of the brain of Tritonia hombergii are described. The brain contains giant neurons which are regularly found in the same positions: cerebral ganglia, one in each; pleural, nine; pedal, eight; buccal, two. The two cerebral giant neurons show spontaneous activity which is inhibited by stimulation of the cerebral nerves. The two largest cells in the pleural ganglia are not spontaneously active but have orthodromic excitatory connexions with axons in the pleural nerves. The branching of the axons of the giant cells has been followed using electrophysiological methods. The axons of a particular giant cell are distributed in a symmetrical fashion to nerves arising on both sides of the brain. This pattern of distribution is similar to that of the corresponding cell in the opposite half of the brain.
The Penetration of Acetylcholine into the Central Nervous System of the Cockroach Periplaneta Americana L
Authors: Lord K. A. , Gregory G. E. , Burt P. E.
Published: April 2021

The hydrolysis of acetylcholine and acetylthiocholine by cockroach ventral nerve cords was examined by biochemical and histochemical methods, and used as an indication of the penetration of the substrates into the nerve cord. The rate of penetration of acetylcholine into intact nerve cords, measured biochemically, agrees well with estimates by Treherne & Smith (1965b) using a more direct method. A barrier to the penetration of the two cholinesterase substrates is destroyed by treatment with acetone, which increased the rate of hydrolysis of acetylcholine five- to tenfold. Histochemical tests showed that acetylthiocholine is probably prevented from penetrating freely to the neuropile of the ganglia by the glial cell layer. When the restriction is abolished by treating the cord with acetone, acetylthiocholine reaches the neuropile but penetrates it for only a short distance, probably because it is decomposed by the cholinesterase in this region.
Osmoregulation in the Diamondback Terrapin, Malaclemys Terrapin Centrata
Authors: Bentley P. J. , Bretz W. L. , Schmidt-Nielsen Knut
Published: April 2021

While in hypertonic environment diamondback terrapins (Malaclemys centrata) slowly lose water by osmosis through the integument and as urine through the kidney. Small amounts of sodium are gained, probably largely as a result of diffusion through the integument rather than by drinking, and this sodium is principally excreted extrarenally. Nevertheless, the solute concentration in the blood of such turtles increases. When returned to fresh water the animals rehydrate and excrete accumulated excess sodium. In these ways they could undoubtedly survive for extended periods in the absence of fresh water, but it is not clear whether they could do so indefinitely.
The Respiration of Pteroides Griseum (Bohadsch) a Pennatulid Coelenterate
Authors: Brafield A. E. , Chapman G.
Published: April 2021

It has been shown that the oxygen consumptions of various anthozoans are generally comparable with those of other invertebrates if the dry weights rather than the wet weights are considered (Brafield & Chapman, 1965). We have also suggested that the endoderm is probably the major site of oxygen uptake in pennatulids, associated with water movements into and out of the enteron. Three main sources of evidence support this view. First, the enteric water has a low oxygen concentration. Secondly, a fully contracted specimen consumes oxygen at a low rate, possibly due to a severely limited enteric circulation. Thirdly, measurements of the oxygen concentration of the water around a specimen in a closed vessel are sometimes inconsistent. Such variations might well be partly due to fairly regular movements of water in and out of the enteron, the inconsistent estimations having been made either just before or after an efflux of relatively deoxygenated enteric water. This source of inaccuracy in measuring consumptions can be avoided only if the oxygen concentration is measured continuously. Consequently experiments have been conducted in which a continuous-flow respirometer was used in an attempt to demonstrate whether a rhythmic enteric irrigation does occur in pennatulids; for if it does, and water which has become partly deoxygenated by oxygen uptake through the endoderm is periodically expelled from the enteron, a continuous record of the oxygen concentration of water which has been flowing slowly past the animal should show a rhythmic rise and fall. Pteroides griseum was used in these experiments because this species has a spacious enteron, and because a good supply of large specimens was available.
Respiratory Function in the South American Lungfish, Lepidosiren Paradoxa (Fitz)*
Authors: Johansen Kjell , Lenfant Claude
Published: April 2021

Few animal species have aroused as much excitement upon their discovery as the South American lungfish. Its possession of distinct piscine as well as amphibian characters made the animal a link in the transition of vertebrate life from water breathing to air breathing. Its special attributes are clearly reflected in its name, Lepidosiren paradoxa.
Active Transport of Potassium and Oxygen Consumption in the Isolated Midgut of Hyalophora Cecropia
Authors: Harvey W. R. , Haskell J. A. , Zerahn K.
Published: April 2021

Flux measurements with 42K reveal that in the isolated midgut of Hyalophora cecropia 90 to 100 % of the short-circuit current is carried by the active transport of potassium from the blood-side to the lumen. When K-transport is strongly depressed, either by withholding potassium from the blood side or by imposing a large positive potential on the lumen, the oxygen uptake of the isolated gut remains virtually unchanged. If the K-transport were to be energized by the negligible increase in oxygen uptake about 40 μ-equiv. of potassium would have to be transported for every μ-equiv. of extra oxygen taken up. This ratio of K-transport to oxygen uptake is thermodynamically impossible. The ratio of potassium transported to total oxygen consumed when the midgut is bathed with 32 mM potassium on both sides is about 1·3 at temperatures of 25° and 15° C. The ratio must be smaller at lower potassium concentrations and is 2·0 at 73·5 mM-K, which may be approaching the maximum value. Although the oxygen uptake is independent of the K-transport, the reverse is not true. There is a close dependency of K-transport on oxygen consumption. K-transport by the midgut contrasts with Na-transport by the frog skin because Na-transport stimulates oxidative metabolism whereas K-transport does not. Evidently the coupling of transport to energy supply is different in the two systems.
Changes in Blood Pressure, Heart Rate and Breathing Rate During Moderate Swimming Activity in Rainbow Trout
Authors: Stevens E. Don , Randall D. J.
Published: April 2021

Changes in blood pressure in the dorsal aorta, ventral aorta and subintestinal vein, as well as changes in heart rate and breathing rate during moderate swimming activity in the rainbow trout are reported. Blood pressures both afferent and efferent to the gills increased during swimming and then returned to normal levels within 30 min. after exercise. Venous blood pressure was characterized by periodic increases during swimming. The pressure changes were not in phase with the body movements. Although total venous return to the heart increased during swimming, a decreased blood flow was recorded in the subintestinal vein. Heart rate and breathing rate increased during swimming and then decreased when swimming ceased. Some possible mechanisms regulating heart and breathing rates are discussed.
Changes of Gas Concentrations in Blood and Water During Moderate Swimming Activity in Rainbow Trout
Authors: Stevens E. Don , Randall D. J.
Published: April 2021

Changes in partial pressures of O2 and CO2 in blood and water afferent and efferent to the gills are reported. These variables were measured before, during and after moderate swimming activity in rainbow trout. Neither blood nor water , afferent or efferent to the gills, changed markedly before, during or after exercise. Arterial blood was always more than 95 % saturated with oxygen. Venous blood was 38% saturated, falling to a minimum of 28% during exercise. of arterial blood was 2-3 mm. Hg. of venous blood increased from 5·7 to 8·0 mm. Hg during exercise and remained elevated throughout the recovery period. Cardiac output (calculated using the Fick principle) stroke volume, ventilation volume and the volume of water pumped per breath all increase by a factor of between 4 and 5 during exercise. All tended to remain elevated for between 10 and 30 min. after exercise and then gradually decrease to pre-exercise levels.
Lactic and Succinic Acids as Excretory Products of Polymorphus Minutus (Acanthocephala) in Vitro
Authors: Crompton D. W. T. , Ward P. F. V.
Published: April 2021

The acanthocephalan parasite, Polymorphus minutus, has been found to excrete radioactive lactic and succinic acid, and a small amount of radioactive, volatile material, when incubated with [U-14C]-glucose under conditions designed to simulate those in vivo. The acids were identified by paper and gas chromatography, and the identity of succinic acid was confirmed with an enzyme preparation.
Flight in Drosophila
Authors: Vogel Steven
Published: April 2021

The variation of the lift and drag of fruit-fly wings with angle of attack and velocity was compared with that of thin plates. High drag and low ratios of lift to drag characterized these airfoils, the primary difference being the absence of stalling in the fly wings. Flow photographs and determinations of stall point on thin plates suggested that the fly wing behaves as if encountering a Reynolds number below the actual value. At positive angles of attack camber improved the aerodynamic characteristics of fly wings; at negative angles uncambered wings were superior. The structural basis for the performance of fly wings and the relationship of their characteristics to their opening conditions are discussed.
Excitation and Inhibition of the Reflex Eye Withdrawal of The Crab Carcinus
Authors: Sandeman D. C.
Published: April 2021

Damage to the statocysts or section of the oesophageal connectives of Carcinus causes repeated ‘spontaneous’ eye withdrawals or ‘blinking’ on the damaged side. When the eyes and brain are isolated from the body, repetitive blinking persists and concomitant bursts of large impulses appear in a single motor axon in the optic tract. The length of these bursts varies from 80 to 180 impulses and the interburst intervals from 5 to 60 sec. There is no obvious correlation between burst length and interburst interval. The bursts are inhibited by stimulating the inside half of the ipsilateral oesophageal connective or initiated by stimulation of the oculomotor and tegumentary nerves. If stimulated with a continuous train of pulses these pathways also cause an increase or decrease in the interburst intervals. The actively spiking portion of the eye-withdrawal motor neuron extends into the brain at least as far as the tegumentary/antennary neuropile. Here it is particularly sensitive to cathodal stimulation, yielding trains of spikes to maintained d.c. stimulation. This point is considered to be near the spike initiating locus for the bursts.
Non-Dependence of the Saturation of Depot Fat on Temperature and Photoperiod in a Hibernating Mosquito
Authors: Van Handel Emile
Published: April 2021

The opinion that fat cells can sense and respond to temperature so as to provide a triglyceride mixture with a melting point just below the environmental temperature (Lands, 1965) is widely held. This view disregards the fact that the body fat of most marine animals, including homeotherms, is highly unsaturated and has melting points much below environmental temperatures, whereas the final melting point of beef tallow and lard may be considerably above body temperature. In the bat, brown adipose tissue fat is less saturated in the summer than during hibernation (Wells, Makita, Wells & Krutzsch, 1965). In hamsters, body fat becomes less saturated after cold exposure, but this effect may be only indirectly due to temperature, because the same effect results from semi-starvation or cortisone treatment at normal temperature (Kodama & Pace, 1963). Furthermore, the fatty acid composition of the diet may greatly affect the body-fat composition and influence the results obtained by variation of temperature.