bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Biology, Pure and Applied
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
THE GEORGE BIDDER LECTURES
The Society for Experimental Biology, with the generous support of the Company of Biologists Ltd., have instituted a series of formal public lectures to be given by distinguished members of the Society, and subsequently to be published in the Journal of Experimental Biology. The series is named after Dr George Bidder, who played an important role in the founding of both the Company and the Society.
A. P. M. LOCKWOOD Hon. Zool. Sec.
N. SUNDERLAND Hon. Bot. Sec.
Society for Experimental Biology
The first George Bidder lecture, given at the Imperial College of Science and Technology, 5 January 1971:
An Analysis Of Pre-Flight Warm-Up In The Sphinx Moth, Manduca Sexta
Authors: Heinrich Bernd , Bartholomew George A. 
Published: April 2021

ABSTRACT
The physiology of pre-flight warm-up in Manduca sexta was analysed with regard to rate of heat production, regional partitioning of heat between thorax and abdomen, and the control of blood circulation.
When moths which have come to equilibrium with ambient temperature undergo pre-flight warm-up, the thoracic temperature increases linearly until flight temperature (37 –39 °C) is approached. The rate of increase in thoracic temperature during warm-up increases directly with ambient temperature from about 2 °C/min at 15 °C to about 7 ·6 °C/min at 30 °C. The temperature of the abdomen remains near ambient throughout the period of warm-up, but during the initial part of post-flight cooling while thoracic temperature declines sharply abdominal temperatures rise appreciably. During warm-up the rate of wing vibration increases linearly with thoracic temperature. At a thoracic temperature of 15 °C the rate is about 8/sec and at 35 °C it is about 25/sec. When resting animals are held by the legs they at once begin to beat their wings through a wide angle. These wing beats at any given thoracic temperature are slower than the wing vibrations characteristic of normal warm-up, but they cause thoracic temperature to increase at almost the normal rate. The removal of thoracic scales causes a decrease in rate of warm-up, but in still air this does not prevent the moths from reaching flight temperature. During cooling the rate of decrease in thoracic temperature is greater in live animals than in freshly killed ones. At any given difference between thoracic and ambient temperatures cooling rates are directly related to thoracic temperature. In resting moths heart pulsations are usually variable with regard to rate, amplitude, rhythm, and sometimes direction, but the records of cardiac activity simultaneously obtained from thorax and abdomen show close correspondence. During warm-up the records of changes in impedance from electrodes in the abdomen indicate that pulsations of the abdominal heart are either absent, greatly reduced, or at a frequency different from that simultaneously recorded from the thorax. The calculated rate of heat production during warm-up is linearly related to thoracic temperature. Our data are consistent with the assumption that heat produced in the thorax during warm-up is sequestered there by reduction in blood circulation between thorax and abdomen. Rates of warm-up in insects are close to the values predicted on the basis of body weight from data on heterothermic birds and animals.
The Swimming of Nymphon Gracile (Pyconogonida)
Authors: Morgan Elfed 
Published: April 2021

ABSTRACT
The organization of the swimming legs of N. gracile has been described. The legs beat ventrally so the animal swims with the dorsal side foremost. The joints between the major segments of the leg are extended for most of the power stroke, but the distal segments articulate sequentially later in the beat, commencing with the flexion of the femoro-tibial joint at the end of the power stroke. Continued flexion reduces the leg radius considerably during the recovery stroke. Animals swimming at constant depth were found to have a leg-beat frequency of about 1 beat/s. Above this the rate of ascent increased rapidly with increasing frequency of beat. Abduction or adduction of the leg usually occurred prior to the start of the power stroke with the femur in the elevated position. Assuming a fixed limb profile at constant angular velocity, maximum lift was calculated to have occurred with the femur inclined at an angle of about 50 ° to the dorso-ventral body axis. The outward component of the lateral thrust decreased to zero at this point, and with further declination of the femur the lateral forces became inwardly directed. Of the different segments of the leg, tibia 2 and the tarsus and propodium contribute most of the hydrodynamic force. The angular velocity of the leg varied during the power stroke, and the actual forces generated during two beats having the same amplitude and angular velocity but of high and low elevation were calculated. Greater lift occurred during the high-elevation beat when the leg continued to provide lift throughout the power stroke, whereas the low-elevation beat acquired negative lift values towards the end of the powerstroke. The lateral thrust was now directed entirely inwards.
Separation of Receptor and Lamina Potentials in the Electroretinogram of Normal and Mutant Drosophila
Authors: Heisenberg Martin 
Published: April 2021

ABSTRACT
In Drosophila the retinula cells and the cells in the lamina ganglionaris contribute to the ERG. This is due to extracellular resistance barriers across these cells ; one of these is situated near the proximal ends of the rhabdomeres separating the retinula cell layer from the rest of the fly, the other is situated either within several layers or homogeneously distributed throughout the lamina. Because of their different origin, two components of the ERG, the receptor potential and the lamina potential can be separated experimentally. At high light intensity the receptor potential is larger than the lamina potential. However, under stimulus conditions where the receptor potential is very small (a) at low light intensity, (b) at high intensity but low flash contrast (ΔI/1), (c) at high frequency of stimulation, the lamina potential exceeds the receptor potential. It is suggested that these properties reflect summation and adaptation of the sensory input within the lamina. The shape of the lamina potential has, under these conditions, the characteristics of a high-pass filter and may improve the fly ‘s response to high stimulus frequencies. The ERGs of the mutants ebony, tan and opm 2 have normal or nearly normal receptor potentials but at the same time demonstrate severe defects in the lamina potentials. In ebony a fast on-effect at high intensity, and in tan a delayed off-effect at high intensity, are still present. The mutant opm 2 shows very little lamina activity at all. The difference of the defects in the three mutants argues against non-specific current leaks in or around the lamina. Therefore it is most likely that the lamina properties of summation, adaptation, and high-pass filtering, are largely lost in the three mutants. This is supported by behavioural experiments.
The Behaviour and Neuromuscular System ofGonactinia Prolifera,a Swimming Sea-Anemone
Authors: Robson Elaine A. 
Published: April 2021

ABSTRACTIn Gonactinia well-developed ectodermal muscle and nerve-net extend over the column and crown and play an important part in the anemone’s behaviour. Common sequences of behaviour are described. Feeding is a series of reflex contractions of different muscles by means of which plankton is caught and swallowed. Walking, in the form of brief looping steps, differs markedly in that it continues after interruptions. Anemones also swim with rapid tentacle strokes after contact with certain nudibranch molluscs, strong mechanical disturbance or electrical stimulation. Swimming is attributed to temporary excitation of a diffuse ectodermal pacemaker possibly situated in the upper column. From the results of electrical and mechanical stimulation it is concluded that the endodermal neuromuscular system resembles that of other anemones but that the properties of the ectodermal neuromuscular system require a new explanation. The size and spread of responses to electric shocks vary with intensity, latency is variable and there is a tendency to after-discharge. There is precise radial localization, for example touching a tentacle or the column causes it to bend towards or away from the stimulus. A model to explain these and other features includes multipolar nerve cells closely finked to the nerve-net which would act as intermediate motor units, causing local contraction of the ectodermal muscle. This scheme can be applied to other swimming anemones but there is no evidence that it holds for sea anemones generally.
Blood Gas Relationships in the Rainbow Trout Salmo Gairdneri
Authors: Eddy F. B. 
Published: April 2021

ABSTRACT
Oxygen dissociation curves were determined using blood from rainbow trout, acclimated for at least 3 weeks to temperatures of 6, 15 and 20 °C. Carbon dioxide tensions in the range 0·3–7 mmHg produced both the Bohr and Root effects in the blood. Increasing temperature, and hydrogen ions, whether raised individually or together, caused a decrease in blood O2 affinity (increased value for P50). Blood at low temperatures had a higher pH than blood at high temperatures. This is related to the fact that the ionization constant of water is diminished with decreasing temperature. When blood was 50 % saturated and was 1 mmHg, the pH value was 8·25 at 6 °C, 7·83 at 15 °C and 7·62 at 20 °C. The factors influencing unloading of oxygen from the blood are discussed. To release the same amount of oxygen from blood, a greater change in carbon dioxid tension is required at 6 °C than at higher temperatures. The Bohr effect expressed quantitatively (ΔlogP50/ΔpH) was –0·54 at 6°C, –0·57 at 15 °C and –0·59 at 20 °C. These values are similar to those for the blood of many mammals, and are within the range reported for fish, where whole blood has been used.
Audition in the Desert Locust: Behavioural and Neurophysiological Studies
Authors: Yinon U. , Shulov A. , Tsvilich R. 
Published: April 2021

ABSTRACT
The auditory responses of the desert locust Schistocerca gregaria were tested using electrophysiological and behavioural methods. The electrical response of the tympanal nerve to pure tone stimuli showed maximum sensitivity between 3 and 5-5 kcyc/sec. The response was the same in both sexes. The flight behaviour was tested as function of pure tone stimuli and measured as the delay period, the number of insects reacting and the time they spent flying. The number of animals which began to fly after the various tones presented was in accordance with the electrophysiological results. The number of animals having a short delay period (under 30 sec) was considerably higher than in the controls for the various sound stimuli. The number of rounds flown (or time spent in flying) was the most affected parameter, although no systematic response was seen as a function of the tone ‘excitation’ by pure tone stimulus and ‘inhibition’ by ‘white’ noise. These two kinds of stimuli were presumably learned by the animal during successive repetition of the stimuli were presumably learned by the animal during successive repetition of the stimulation procedure. The usefulness of sound emission during flight and sound perception (by the hearing organ) was discussed. The auditory neural mechanism of the desert locust is presumably integrated with the visual mechanism for communication purposes between swarming animals.
Variable Responsiveness of A Visual Interneurone in the Free-Moving Locust, and its Relation to Behaviour and Arousal
Authors: Rowell C. H. Fraser 
Published: April 2021

ABSTRACTRecorded from a dissected immobilized animal, or from an unrestrained animal which is quiescent, the descending contralateral movement detector (DCMD) neurone shows an exponential decremental response to a repetitive stimulus (habituation), reaching a plateau level characteristic of the stimulus conditions. The process is sitespecific on the retina, and movement to a new area of retina gives a complete recovery. In the absence of stimulation responsiveness returns over minutes or hours. Immediate recovery without a rest (dishabituation) can be obtained by a variety of strong sensory stimuli of several different modalities (‘extra-stimuli’) or by non specific electrical stimulation of parts of the CNS. The dishabituating efficacy of all these wanes with repetition. When the habituating stimulus is moved to a new retinal site the previous site is not dishabituated. Dishabituation is not site-specific but affects the whole retina simultaneously. It appears to reverse the original decremental process (‘re-set’) rather than to produce an independent enhancement elsewhere in the pathway, as it does not increase the response from a submaximally stimulated, but unhabituated, retinal site. In unrestrained animals dishabituating extra-stimuli also cause behavioural arousal or other motor activity. When motor activity starts, the DCMD is dishabituated and shows no regular decremental trend thereafter until movement ceases. DCMD background activity is also increased. These effects are not due to the visual stimulus of the moving appendages. The association between motor activity and dishabituation suggests that the latter derives either from motor system collaterals or from mechanoreceptive reafference. Stimulation of the antennal nerve of a totally de-efferented brain cause some dishabituation; this eliminates the lower motor system (below command-fibre level) as the source of dishabituation and suggests it is purely sensory. The activity of a thoracic cord unit (of possibly a wide-field mechanoreceptor interneurone) precedes by 5–20 sec, and closely correlates with, changes in responsiveness of the DCMD. It is either an important input to, or an output from, the dishabituating system. Progressive reduction of sensory input to the brain affects DCMD responsiveness as follows: (i) spontaneous dishabituation is less frequent, (ii) dishabituation is less easily induced and smaller, (iii) rate of habituation is increased, (iv) plateau response level after habituation is lower. Electrical stimulation of the circumoesophageal connective can depress DCMD responsiveness for many minutes. The probable anatomical and physiological bases for modulation of DCMD responsiveness are discussed.
Connective Tissue Mechanics ofMetridium Senile: I. Structural and Compositional Aspects
Authors: Gosline John M. 
Published: April 2021

ABSTRACTThe body-wall connective tissue (mesogloea) of the sea anemone Metridium senile constitutes the highly extensible, tensile container for the hydrostatic skeleton of this animal (Wainwright, 1970). Light-microscopic (Chapman, 1953 a) and electron-microscopic (Grimstone, Horne, Pantin & Robson, 1958) studies of anemone mesogloea show this tissue to be densely fibrillar, with the fibres forming right-handed and left-handed helices around the columnar body wall. The fibrous component has been identified as a collagen on the basis of periodic banding in electron micrographs (Grimstone et al. 1958; Piez & Gross, 1959; Batham, 1960) and of amino acid analyses (Piez & Gross, 1959).
Transepithelial Potential Changes During Stimulation of Isolated Salivary Glands with 5-Hydroxytryptamine and Cyclic Amp
Authors: Berridge Michael J. , Prince William T. 
Published: April 2021

ABSTRACT
The role of cyclic AMP in mediating the action of 5-HT on salivary glands has been studied by measuring transepithelial potentials. The lumen of unstimulated glands is 4 mV positive but becomes 12 mV negative after treatment with 5-HT (10−8M). Both the potential and the secretory responses to 5-HT are dose-dependent over the same concentration range. The electrical response of salivary glands to cyclic AMP is qualitatively different to that of 5-HT; instead of going negative the potential goes more positive. An increase in positive potential is also observed after treatment with theophylline (10−2M), or when glands are stimulated with 5-HT in a chloride-free saline. These results are consistent with the idea that 5-HT has two actions. One is to stimulate the enzyme adenyl cyclase to synthesize cyclic AMP, which, in turn, stimulates cation transport. The other is to increase anion transport by a mechanism which is independent of cyclic AMP.
A Study in Jet Propulsion: An Analysis of the Motion of the Squid, Loligo Vulgaris
Authors: Johnson W. , Soden P. D. , Trueman E. R. 
Published: April 2021

ABSTRACT
A method is presented which allows the jet thrust and motion of a cephalopod to be calculated from basic information on its shape and material properties. A simple model is used to illustrate the technique, and the results are compared with experimental data for Loligo vulgaris. Agreement between theoretical and experimental results is shown to be reasonably good. This approach could be applied to other cephalopods and other animals using jet propulsion.
Central Programming and Reflex Control of Walking in the Cockroach
Authors: Pearson K. G. 
Published: April 2021

ABSTRACT
The activity in identified motor units supplying the coxal levator and depressor muscles of the cockroach have been recorded in intact freely walking animals and in preparations after removal of all sensory input from leg receptors. Reciprocal activity in levator and depressor motoneurones can be evoked, or occurs spontaneously, in the partially de-afferented preparations, thus indicating the existence of a central locomotory rhythm generator. The reciprocal activity patterns recorded in the same motoneurones in intact freely moving animals are not identical to those recorded in partially de-afferented preparations. Thus, the production of normal rhythmic leg movements depends to some extent on sensory input from leg receptors, this input probably exerting tonic and phasic effects on the central rhythm generator. An increase in the resistance to leg retraction during normal walking results in an increase in discharge rate of the levator and depressor motoneurones. This observation further demonstrates that rhythmic leg movements are not exclusively centrally controlled. The receptors responsible for this reflex effect are probably the trochanteral campaniform sensilla.
The Growth of Moniliformis Dubius (Acanthocephala) in the Intestine of Male Rats
Authors: T. Crompton D. W. 
Published: April 2021

ABSTRACT
The helminth Moniliformis dubius forms a convenient source of material for studying the biochemistry and physiology of acanthocephalans because it grows to a relatively large size and its life-cycle is easily maintained in the laboratory. The parasite develops in the haemocoele of the cockroach Periplaneta americana and sexual maturity is achieved in the small intestine of rats. Biochemical work on helminths, however, will progress slowly until the worms in question have been cultured in vitro. One difficulty with culture work is the selection of a trustworthy means of assessing growth. Measurements of the lengths and wet weights are unreliable, and the aim of the work described below was to measure the protein nitrogen, the DNA and the RNA content of M. dubius during the course of its infection in rats. These results could then be used to monitor the growth of worms being kept in vitro and to form the basis for experimental studies of their growth in vivo.
The Corpus Allatum and Oogenesis inRhodnius Prolixus(Stål.)
Authors: Pratt G. E. , Davey K. G. 
Published: April 2021

ABSTRACTIn the ovarioles of both normal and allatectomized females the spaces open between the cells of the follicle layer and vitellogenesis begins as the terminal oocyte grows through the 350–400 μm size range. In both normal and allatectomized ovarioles the growth of the larger oocytes is markedly co-ordinated so that, for example, each ovariole contains only one oocyte in active vitellogenesis. A consideration of the size distribution of the terminal oocytes in normal and allatectomized ovarioles demonstrates that vitellogenesis begins later and proceeds more slowly in allatectomized animals. Allatectomy markedly depresses the number of mitoses in the trophic primordium, but this is held to be a feedback phenomenon resulting from a decreased demand for the products of mature trophocytes. There is a decreased level of yolk protein in the haemolymph of allatectomized animals. This evidence favours the hypothesis that the primary site of action in Rhodnius of the gonadotropin from the corpus allatum is situated at the level of activation, whereby spaces open between the follicle cells and proteins from the haemolymph are allowed free access to the oocyte surface.
The Evolution of Kidney Function in the Neritacea (Gastropoda, Prosobranchia)
Authors: Little Colin 
Published: April 2021

ABSTRACT
Gastropod molluscs of the superfamily Neritacea (or order Neritacea: see Morton & Yonge, 1964) are found in marine, freshwater and terrestrial environments; but despite these wide differences in habitat the general anatomical organization is similar in all the members of the group. In particular the organization of the renal system appears to be very similar in marine and freshwater species, and to be not greatly altered in the terrestrial forms. This is surprising in a group subjected to the apparently different problems posed by life in these various environments.
Respiration, Wing-Beat and Ultrasonic Pulse Emission in an Echo-Locating Bat
Authors: Suthers Roderick A. , Thomas Steven P. , Suthers Barbara J. 
Published: April 2021

ABSTRACT
During flight, echo-locating bats must adjust their pulmonary ventilation to satisfy a variety of requirements. The basic role of respiration, in gas exchange and in the maintenance of physiological homeostasis under exercise stress, must be achieved in a way that is compatible not only with the rhythmic contraction of powerful flightmuscles but also with the continual production of high-intensity vocalizations necessary for acoustic orientation. Moreover, the demand for accurate navigational information is often greatest during the stresses of rapid erratic flight. At such times bats continually emit brief, high-intensity orientation sounds at repetition rates varying from a few to many per second. Nothing is known regarding the relationship between respiration, sound production and wing movements during flight, or the extent to which changes in pulse-repetition rate affects respiration.
Water Content and Water Activity in the Cuticle of Terrestrial Isopods
Authors: Lindqvist Ossi V. , Salminen Inga , Winston Paul W. 
Published: April 2021

ABSTRACT
The water content of the cuticle of both desiccated and non-desiccated terrestrial isopods Porcellio scaber and Armadillidium vulgare was measured. The animals were desiccated for various times (up to 3 h) over silica gel and the mean water content of the cuticle was 54·0 ± 0·78% for P. scaber and 52·7 ± 1·11% for A. vulgare. There was no trend as regards the desiccation time, nor did the body weight affect the water content. The water content of the cuticle remained virtually unchanged as long as the animal was alive in the desiccator. It dropped significantly after the animal had died after having lost some 30 % of its body weight. The cuticular water content of non-desiccated P. scaber tended to be slightly higher than that of desiccated ones. In A. vulgare no significant difference was observed between non-desiccated and desiccated specimens. The water activity of the excised cuticle of the above two species and of Oniscus asellus and Cylisticus convexus was above that of the haemolymph and therefore not in osmotic equilibrium with it. The osmotic equilibrium points were below the osmotic pressures of the blood; the difference amounted from 1·5 to 2·8 atm. in different species. The difference in water activity between blood and cuticle, the maintenance of water content with desiccation, and the drop in water level at death, all indicate the presence of an active mechanism regulating the cuticular water in terrestrial isopods.