bluuebunny/crossref_metadata_2025 huggingface dataset:
Excretion in the Cephalopod, Octopus Dofleini
Authors: Harrison F. M. , Martin A. W.
Published: April 2021

Although excretory processes in vertebrate animals have been studied extensively during the past fifty years, comparatively few investigations have been carried out on invertebrates. The cephalopod molluscs represent a group which is suited to experimental study due to the large size that has been attained by some of the forms, their relatively high and constant level of metabolic activity and the presence of excretory structures which are accessible and well defined. For these reasons a study was initiated on the large octopus of Puget Sound, Octopus dofleini martini (Pickford, 1964).
Copulation and Egg-Production in Rhodnius Prolixus: The Role of the Spermathecae
Authors: Davey K. G.
Published: April 2021

Mated females of Rhodnius prolixus lay eggs at approximately twice the rate of unmated females. Males which have had their seminal vesicles or opaque accessory glands removed produce spermatophores at mating, but no spermatozoa appear in the spermathecae of the females. The females involved in such matings do not exhibit an increase in eggproduction. When females lacking their spermathecae are mated to normal males, the increase in egg production which follows normal matings does not materialize. Implanting spermathecae from mated females into virgin females increases the egg-production of the host. Implanting spermathecae from virgin females or seminal vesicles or transparent accessory glands from males has no effect on the egg-production of the donor. It is tentatively concluded that a blood-borne factor from the spermathecae containing spermatozoa is the primary stimulus to increased egg production in a mated female.
The Electrical Potential Difference Across the Epithelium of Isolated Gills of the Crayfish Austropotamobius Pallipes (Lereboullet)
Authors: Croghan P. C. , Curra R. A. , Lockwood A. P. M.
Published: April 2021

A technique is described for recording the electrical potential differences across the epithelium (epithelial potential) of isolated podobranch gills of Austropotamobius pallipes continuously perfused with Ringer solution in various external media. In a medium of 0·01 Ringer, in which the animals had previously been kept, the mean epithelial potential ± standard deviation was —60 ±12 mV. (Sign defines potential of body fluid with respect to external medium.) Chloride, sodium and potassium must be actively transported into the body fluid against an electrochemical gradient. Calcium and magnesium ions appear to be approximately in equilibrium. The steady-state membrane potentials were recorded in various external concentrations of Ringer solution. The potential is about zero with Ringer solution outside and rises to a maximum with 0·01 Ringer outside. Changes of the electrical potential were recorded when the concentration of a single electrogenic ion was changed in the external medium (0·01 Ringer), and were used to define an apparent transport number of the ion in the outer cell membrane. There was no correlation between the transport numbers and the epithelial potential. There was a continuous gradation of gill types from a predominantly cation-permeable type towards a more chloride permeable type. There is a correlation between the type of gill and the position in the gill series. The properties of the epithelial cells of Austropotamobius gill are significantly different from those of the epithelial cells of frog skin. It is suggested that in Austropotamobius a chloride pump is situated in the outer cell membrane.
The Thermal Dependence of Flagellar Activity in Strigomonas Oncopelti
Authors: Holwill M. E. J. , Silvester N. R.
Published: April 2021

The flagellar beat frequency of Strigomonas oncopelti was found by cinémicro-photography at temperatures in the range 4 − 45 ° C. The thermal dependence is described by an activation enthalpy (ΔH‡) of 15·4 kcal./mole and an activation entropy (ΔS‡) of — i e.u. ΔH‡ is comparable with published data on cilia and glycerol-extracted sperm. Values of ΔS‡ ( — 20 e.u.) deduced from the literature suggest a ratelimiting reaction between ions of like charge although the present value does not support this idea.
Eye Movements of the Dogfish Squalus Acanthi As L
Authors: Harris A. John
Published: April 2021

A method for recording the positions of the eyes of a free-swimming dogfish is described. The eyes of the dogfish do not compensate completely for the lateral swinging of the head which occurs during swimming. The labyrinthine apparatus and the extraocular musculature are capable of providing complete compensation, but this compensation is opposed by influences from the spinal cord. Full compensation during swimming would stabilize only objects at infinity. Partial compensation serves to stabilize a plane of reference close to the fish. Eye movements, allied with the normal zig-zag progression of the fish, serve to eliminate the blind area behind the fish. Other movements of the dogfish’s eyes are discussed, and arranged in five categories. Spontaneous movements of the eyes of resting dogfish are described, and related to the eye movements of swimming dogfish. The spontaneous movements are suggested to be manifestations of an otherwise subliminal central excitatory state affecting turning and swimming.
The Penetration of Acetylcholine Into the Central Nervous Tissues of An Insect (Periplaneta Americana L.)
Authors: Treherne J. E. , Smith D. S.
Published: April 2021

14C-labelled acetylcholine was found to penetrate rapidly into the tissues of the intact abdominal nerve cord. Uptake in the presence of 10−4 M eserine occurred as a two-stage process, the initial rapid influx being identified as the penetration into the extracellular system of the nerve cord. There was a more rapid accumulation of radioactivity in normal preparations as compared with those treated with 10−4 M eserine, presumably as a result of intracellular uptake of the products of hydrolysis of the acetylcholine. The level of radioactivity in the rapidly exchanging fraction was consistent with the hypothesis that the acetylcholine ions were distributed in the extracellular fluid according to a Donnan equilibrium with the haemolymph in eserinized preparations. These results are discussed in relation to the possible physiological role of acetylcholine in synaptic transmission in this insect.
The Lift Produced by the Heterocercal Tails of Selachii
Authors: Alexander R. McN.
Published: April 2021

The upward forces produced by tails of dogfish and tope, moving transversely through water at various speeds, have been measured. The lift is approximately proportional to the 1-4 power of the transverse speed. The equilibrium of dogfish and tope, swimming horizontally with the whole body horizontal, is discussed quantitatively. It is estimated that in each case the hypocaudal lobe, acting passively, would give more lift than is required for equilibrium, at all swimming speeds greater than about 0-5 length/sec. The lift may be adjusted to the required value by means of the radial muscles of the hypocaudal lobe.
Non-Sinusoidal Bending Waves of Sperm Flagella*
Authors: Brokaw C. J.
Published: April 2021

Photomicrographs giving greater resolution than previously available have been obtained for the spermatozoa of a sea urchin, a tunicate, and an annelid. The bending waves are not sine waves. They contain circular arcs, in which the amount of bending is constant, separated by shorter regions which are nearly straight. The flagellum must be effectively very stiff to maintain this waveform as it moves through the medium, but this stiffness must be greatly reduced at the junctions between straight and circular regions, where the flagellum is actively bending and unbending. This type of wave pattern may be generated by a simple ‘on-or-off’ activation of bending elements, but the amount of bending which occurs can be influenced by environmental conditions, such as the viscosity of the medium. A mathematical analysis of the wave movement can be carried out more easily than with sinusoidal waves, and expressions have been obtained for the forward swimming speed, the distribution of bending moment along the flagellum, and the energy expenditure for movement, in terms of the parameters of the waves. The expression for the forward swimming speed accurately predicts the swimming speed of headless spermatozoa, confirming the validity of the hydrodynamic assumptions used in this analysis.
Regulation of Transpiration in the Clover MiteBryobia PraetiosaKoch (Acarina: Tetranychidae)
Authors: Winston Paul W. , Nelson V. Eugene
Published: April 2021

Groups of sixteen mites were starved for 48 hr. at 29% R.H. and then exposed for 18 or 24 hr. to one of nine humidities, from 0% to 93% R.H. They were weighed as groups before and after the treatments to determine total weight loss. Dry weights were also obtained to find water content and for the calculation of water and dry-weight losses. All work was done at 25° C. Water loss, considered equivalent to total weight loss, was also obtained under several other conditions; and at all humidities it was found to be highest in mites killed in chloroform vapour while it was considerably less in those killed in HCN gas. Mites with spiracles kept open by air with 10% CO2 lost weight at rates midway between those for dead and those for living animals. There is apparent regulation of body-water content as a percentage of the final weight over the whole humidity range. Water loss is restricted by a CO2-sensitive mechanism, presumably the spiracles. Active regulation of water loss by a cuticular mechanim was shown between 53% and 85% R.H., while at humidities below this, loss was actively restricted but not regulated. It is postulated that both restriction and regulation are brought about by the same mechanism, which might be a form of active transport. Uptake of water from unsaturated air was not found with any of the methods used. Regulation such as was found here would help to maintain the internal environment of these mites as nearly constant as possible in the face of fluctuating humidities.
The Muscular Basis of the Respiratory Pumps in the Trout
Authors: Ballintijn C. M. , Hughes G. M.
Published: April 2021

An account is given of the muscles and skeleton of the trout head and of the mechanisms coupling the different functional components of the skull. The activity of the main respiratory muscles has been recorded electromyo-graphically and simultaneously with pressure and movement recordings from the buccal and opercular cavities. The muscles may be divided into two main groups according to whether they are active during the expansion or contraction phase of the pumps. The protractor hyoideus (geniohyoideus) was found to be active only during the contraction phase. There are differences in the muscles that are active, depending upon the depth of ventilation. Shallow ventilation is maintained by the adductor mandibulae, adductor arcus palatini et operculi, and levator hyomandibulae et arcus palatini. During deeper ventilation the stemohyoideus, protractor hyoideus and hyohyoideus muscles come into action. Only during strong ventilation does contraction of the dilator operculi play a part in opercular abduction. There are variations in the pattern of muscular activity in different individuals and also in the same individual at different times. Such differences in muscular activity are not clearly reflected in the movement and pressure recordings, because of the complex couplings between different parts of the pumping mechanism. As contraction of most muscles affects both the opercular and buccal cavities it is concluded that a model of teleost ventilation based upon a double pumping mechanism must incorporate the couplings between these pumps.
The Muscular Basis of the Respiratory Pumps in the Dogfish (Scyliorhinus Canicula)
Authors: Hughes G. M. , Ballintijn C. M.
Published: April 2021

The mechanism of gill ventilation in the dogfish has been shown to be fundamentally the same as that found in teleost fishes (Hughes, 1960b; Hughes & Shelton, 1962). Water enters the respiratory system through both the mouth and the spiracle during expansion of the oro-branchial cavity (Woskoboinikoff, 1932) and after passing across the gills it enters the parabranchial cavities before being ejected to the outside through the five pairs of gill slits. The flow across the gills is maintained partly as a result of the increased pressure in front of the gill resistances but also because of the suction pump action of the parabranchial cavities. The muscular activities producing the changes in volume of these two cavities and hence the required pressure gradient across the gills have not been established and descriptions of the relationships of muscles and skeleton are not always clear in detail. Woskoboinikoff (1932) and others were of the opinion that the coraco-mandibularis muscle was of importance during the phase of the cycle when the mouth opens and the oro-branchial cavity expands, but this was categorically denied by Balabai (1938) in a footnote to his paper. From observations on dogfish, anaesthetized so that they no longer pumped water across their gills, it was suggested (Hughes, 1960 a) that the main muscular action during the cycle was due to the constrictor muscles. These compress the branchial region and on their relaxation the elastic properties of the skeleton and ligaments are sufficient to account for expansion of the parabranchial cavities. A dogfish in this condition can be made to pump water through its respiratory system by compressing the branchial region by hand. It was also clear in Scyliorhinus that, as had also been observed by Satchell (1959) in Squalus, the respiratory cycle begins with a compression and is followed by relaxation and a relatively long respiratory pause.
The metabolism of acetylcholine in the intact central nervous system of an insect (Periplaneta Americana L.)
Authors: Treherne J. E. , Smith D. S.
Published: April 2021

A very rapid metabolism of 3H-labelled acetylcholine has been demonstrated in the intact abdominal nerve cord. It has been shown that the cholinesterase system is effective in drastically reducing the concentration of acetylcholine in the extracellular fluid of the terminal abdominal ganglion with bathing solutions of up to 10−2 M acetylcholine. Evidence has been obtained which indicates that an appreciable hydrolysis of acetylcholine occurs at the periphery of the nerve cord. This effect is correlated with the electronmicroscopic demonstration of regions of eserine-sensitive cholinesterase located on glial membranes in the periphery of ganglia and connectives. It is suggested that some hydrolysis of extraneous acetylcholine may occur in the fibrous layer of the nerve sheath as a result of an accumulation of diffusible acetylcholinesterase in this region. The results are discussed in relation to the possible involvement of the conven­tional cholinergic system in synaptic transmission in the central nervous system of this insect.
The Physiology of Excretion in the Cotton Stainer, Dysdercus Fasciatus Signoret: III. Nitrogen Excretion and Excretory Metabolism
Authors: Berridge M. J.
Published: April 2021

The nitrogenous components of the urine are: allantoin, urea, amino acids, kynurenine, and a mucopolysaccharide. The main nitrogenous excretory product is not uric acid, as in other terrestrial insects, but allantoin. The excretion of total nitrogen, allantoin nitrogen, urea nitrogen and amino acid nitrogen have been followed throughout the excretory phase. The concentration of allantoin in the urine is always less than that in the haemolymph, and is a result of the low permeability of the Malpighian tubules to this substance. When isolated Malpighian tubules were used the average U/P ratio was 0·45. Waste nitrogen is also excreted by storage excretion of uric acid in the epidermal cells ; the rate of deposition is most rapid during the excretory phase. Low allantoin excretion and a low rate of uric acid deposition in the epidermis during the post-excretory phase suggest that uric acid synthesis is markedly reduced during this phase. Uricase is concentrated in the Malpighian tubules, where it accounts not only for the absence of uric acid in the urine but also for the high concentration of allantoin in the haemolymph. Calculations based on allantoin excretion show that only 28% of the primary tubule fluid is reabsorbed from the rectum. Since allantoin is more soluble than uric acid, it is better suited as a nitrogenous waste substance in such an excretory system, which recycles little water. The method of excreting waste nitrogen is compared with that of other insects.
Split-Brain Preparations and Touch Learning in the Octopus
Authors: Wells M. J. , Young J. Z.
Published: April 2021

A vertical longitudinal cut through the supraoesophageal part of the brain does not prevent discrimination between rough and smooth cylinders. It does, however, prevent correct response by the opposite side after training on one side of the animal. Octopuses with intact supraoesophageal lobes, trained on one side, discriminate when tested with the same objects on the other side; split-brain animals do not. In this situation, the performance of one side of the octopus can be used as a control for the effect of a brain lesion in the other. Removal of large parts from the supraoesophageal brain does not prevent touch-learning. Discrimination continues until the lesion includes the whole of the subfrontal lobe on the side concerned. Some of the small amacrine cells of the subfrontal/posterior buccal region must remain if learning is to occur. There are normally about 2·5 × 106 of these in each side of the subfrontal lobe ; animals continued to discriminate between rough and smooth cylinders with as few as 10,000 of these cells remaining, but failed when none were left. Octopuses with the brain intact or with the vertical lobes removed do not show marked rough/smooth preferences. In animals with large lesions to the inferior frontal system, however, there is a preference for rough, so that rough +/smooth — is an easier discrimination than vice versa.
The Nervous Pathways for Poisoning, Eating and Learning in Octopus
Authors: Young J. Z.
Published: April 2021

Octopuses after removal of the lip kill and eat crabs apparently normally. They learn to attack a strange figure moving in the visual field. The pair of nerves that originates from cells at the back of the superior buccal lobe is shown to be responsible for the discharge of secretion from the posterior salivary glands. If this pair of nerves is interrupted the octopus does not poison a crab after catching it. It still eats, however, and learns to attack a strange figure. If both interbuccal connectives have been severed the octopus does not remove the flesh properly from crabs. It does not learn to attack a strange figure. Any operation on the central nervous system that interrupts the pathway from the interbuccal connectives to the lateral superior frontal and optic lobes prevents learning to attack a figure that has been seen. If such cuts pass through the middle of the superior buccal lobe the animal does not poison crabs or completely remove the flesh from their exoskeletons. If the cut is through the back of the superior buccal lobe the octopus does not poison crabs but may tear them open and then clean and eat them. With cuts still farther back the animal poisons, cleans and eats crabs, but still does not learn to attack.
Sensory Modalities and Receptive Fields in the Abdominal Nervous System of the Hermit Crab, Pagurus Granosimanus (Stimpson)
Authors: Chapple William D.
Published: April 2021

The way in which adaptation to a particular environment takes place within the central nervous system of vertebrates has been the subject of research for over a hundred years. The development of specific reflexes from generalized action patterns, the precedence of changes in motor systems over changes in sensory systems, and the metamorphosis of sensory relay nuclei and centres of primary integration into areas subserving more complex functions (Herrick, 1948) are some of the ways in which adaptation is reported to have occurred. Furthermore, Bishop (1961) has suggested that the emphasis upon functional criteria alone as a key to the function of a specific nervous system neglects those features of the system which owe their presence to its evolution from a nervous system adapted to perform other tasks. During their evolution, the newer centres of integration which have developed as a result of new requirements have not abolished the older centres, which may retain many of their old properties. It is clearly of interest to determine whether nervous systems of groups other than vertebrates exhibit the same regularities in their adaptation, and if possible to examine the alterations in response to different selective forces at the single-unit level.
Surface Characters of Dividing Cells
Authors: Ishizaka Shozo
Published: April 2021

Surface movement of the dividing spermatocyte of the grasshopper, Acrida lata, was followed by a marking method. Throughout the division process of the spermatocytes, incipient daughter cells maintain spherical contours. By direct observation of markers and calculation using the condition given in item 2, the following points are established. (a) As in the sea-urchin egg, there are a pair of circular zones on a grasshopper spermatocyte surface which retain their respective radii unchanged while the cell undergoes a division.(b) In the grasshopper spermatocyte, unlike the sea-urchin egg, the surfaces of these circular zones do change their positions and move towards the poles during division.(c) As a spherical cell goes through a constricted form to become two daughter cells, not only is the radius of curvature of the surface everywhere uniform (item 2), but both axial length and surface area increase uniformly everywhere except in the region of the furrow. From the findings of item 3 it is inferred that the prevailing surface stress is uniform and isotropic, like surface tension, and that the force causing division must be derived from some other parts of the cell such as the furrow cortex or the endoplasm. Basically, the nature of the surface of sea-urchin eggs is similar to that of the spermatocyte. That the circular zones of the former are stationary while those of the latter move steadily during cleavage is tentatively explained in terms of the speed of advance of the furrow in relation to the relaxation time of the cortex.
Adaptation and Other Phenomena in the Optokinetic Response of the Crab, Carcinus
Authors: Horridge G. A.
Published: April 2021

During the course of the experiments which have contributed to the previous papers there appeared a number of new observations which did not fit readily into those topics. Although each is a qualitative new finding which seems at first sight to refer to only one aspect of the optokinetic response, taken together they shed further light on the type of system we are dealing with. All of these new observations could be quantified in detail, but it appears that a highly accurate set of measurements which are intended to measure the parameters of one simple system are out of place until a wide variety of qualitative experiments, with suitable controls, have narrowed down the choice of alternative models.
Some Factors Affecting Flight Activity in Individual Milkweed Bugs (Oncopeltus)
Authors: Dingle Hugh
Published: April 2021

Individual adults of Oncopeltus were tested repeatedly at 2- or 3-day intervals, using tethered flight, to determine the amount of flight activity as measured by flight duration. The peak period of activity occurred 8 days after the final moult with later flights scattered and showing no concentration at a particular age. Deposition of cuticular growth rings ceased at about 7 days ; the peak activity was thus post-teneral and probably represents migration. Only 23·8 % of bugs tested showed flights of over 30 min. Those bugs which flew for long periods at 8 days were more likely to show long flights at a later age than were bugs which did not fly at day 8. There thus seems to be a behavioural polymorphism with distinct ‘flyers’ and ‘non-flyers’. More females, 30·7%, than males, 18·1 %, exhibited flights of over 30 minutes. Males which did have such long flights were, however, more likely than females to have them repeatedly. In both sexes virgins seemed to be more active in respect of long flights than bugs allowed continuous contact with the opposite sex. Calculations based on estimates of flight speed and total duration of flight indicate that an individual migrant Oncopeltus is capable of covering a considerable distance, 100 kilometres or more, during its lifetime.
The Effect of Ouabain on the Efflux of Sodium Ions in the Nerve Cords of Two Insect Species (Periplaneta Americana and Carausius Morosus)
Authors: Treherne J. E.
Published: April 2021

The intracellular efflux of 22Na from the nerve cord is reduced by the presence of ouabain in the bathing medium. With Periplaneta 10−6M ouabain caused a reduction in the rate constant for sodium efflux from 3·94 × 10−3 sec.−1 to 1·80 × 10−3 sec.−1 and in Carausius from 1·14 × 10−3 sec.−1 to 6·18 × 10−1 sec.−1. Uncoupling of the energy supply to the sodium pump, by the addition of cyanide, did not further reduce the sodium efflux from ouabain-treated axons, suggesting that the greater part of the active extrusion of this cation is effected by a single ouabain-sensitive carrier mechanism. The relative insensitivity to ouabain of the insect axons, as compared with squid giant axons, is shown to result from the presence of a rather leaky axon membrane in which the carrier-mediated component forms a much smaller part of the total flux. The concentration gradient of sodium across the insect axon membrane is related to the combined effects of the activity of the sodium pump and the passive permeability of the membrane.
Effects of Increased Viscosity on the Movements of Some Invertebrate Spermatozoa*
Authors: Brokaw C. J.
Published: April 2021

Two distinctly different patterns of sperm movement in response to increased viscosity have been found, which appear to be variations in the behaviour of a common mechanism for generating and controlling flagellar bending waves. One type of pattern is found with the normal movements of spermatozoa of Ciona and Lytechinus, and with glycerinated Lytechinus spermatozoa when their movements are reactivated at high (2 mM) ATP concentrations. The radius of curvature of the bends on the flagellum, and the viscous bending moment, remain relatively constant, while the propagation velocity, wave amplitude, and energy expenditure decrease with increasing viscosity. The second pattern of response is found with the normal movements of spermatozoa of Chaetopterus, with Lytechinus spermatozoa when the beat frequency is reduced by the presence of an inhibitor, thiourea, and with glycerinated Lytechinus spermatozoa when their movements are reactivated at low (0·2 mM) ATP concentrations. The decrease in propagation velocity with increasing viscosity is accompanied by substantial reductions in the radius of curvature, and the wave amplitude is not greatly decreased. This response involves an increase in viscous bending moment and energy expenditure as the rate of bending decreases, and may resemble the increased force and work outputs obtainable from muscle at reduced shortening velocities. This type of response is obtained under conditions where the initial beat frequency and energy expenditure are relatively low, and may not be possible when the initial level of energy expenditure is higher. Although each species shows a unique pattern of changes in frequency and wavelength with increasing viscosity, the relationship between bend propagation velocity and viscosity has nearly the same form in each case, indicating that the velocity of bend propagation is relatively independent of the magnitude of the bend. This result is consistent with at least one proposed mechanism for bend propagation. On the basis of this mechanism, the results suggest that the rate of bending is independent of the magnitude of the bend and inversely proportional to the square root of the viscosity. In some cases, the wavelength and other wave parameters are adjusted so that a constant proportionality between viscous and elastic bending moments will be maintained as the viscosity is increased. This proportionality will also be maintained during the passive propagation of bending waves along an inert flagellum, and for an active flagellum it implies that the wave parameters are adjusted so that energy stored in elastic bending of the flagellum could be efficiently used to effect unbending, without indicating how this adjustment is accomplished. Other cases, in which the proportionality between viscous and elastic bending moments is not maintained, may represent cases where the flagellum is not operating efficiently. Under certain conditions the normal nearly planar bending waves of Ciona spermatozoa are replaced by helical bending waves.
Circulation in A Giant Earthworm, Glossoscolex Giganteus
Authors: Johansen Kjell , Martin A. W.
Published: April 2021

Oxyhaemoglobin dissociation curves have been obtained for Glossoscolex giganteus. The t50 value was 7 mm. Hg. at 20° C. and pH 7.58. There was no significant Bohr effect. Oxygen capacity averaged 14.0 vol. % for fifteen animals. The corresponding value for haemoglobin expressed as iron content was 30 mg. %. Blood was sampled anaerobically from the dorsal vessel on non-anaesthetized freely moving specimens and analysed for O2 and CO2 content. Blood-gas levels were studied in animals placed on moist surfaces or buried in shallow moist soil. The effects of drug injections and changes in the composition of the external gases were measured. Patterns of gas exchange and the role of haemoglobin in gas transport in the earthworm are discussed.
The Dimensions of Fish Gills in Relation to Their Function
Authors: Hughes G. M.
Published: April 2021

Measurements have been made of the gill areas of fourteen species of British fish, all marine except for the tench and trout. In addition the gill area of the Antarctic icefish, Chaenocephalus (lacking haemoglobin) has been measured. The different parameters of the gill sieve have been considered quantitatively in relation to the size of the gill area, resistance to the passage of water, and the diffusion conditions at the gills. From calculations of the expected flow through a sieve of the measured dimensions it has been concluded that a sufficient volume would pass in the inter-lamellar spaces despite their fine dimensions. Differences in the nature of the sieve relative to the theoretical one and changes during the respiratory cycle account for the ventilation volumes measured being less than those calculated. The theoretical analysis of the operation of the gill sieve are discussed in relation to measurements of Gray (1954) and to the developmental studies of Price (1931). It is concluded that more active fish not only have larger gill areas but that the conditions for gaseous exchange are better than for more sluggish forms and that the area is increased in such a way as to keep the resistance to flow to a low value. This is mainly achieved by having an increased total filament length and a large number of secondary folds. More sluggish fish have more widely spaced and higher lamellae and their total filament length is reduced. The resistance to flow relative to the area is less in these forms than in the more active species. Consideration is given to the different pathways along which water can infiltrate past the respiratory epithelium and analogies are drawn with the alveolar air, and the physiological and anatomical dead-spaces of the mammalian lung.
The Metabolic Effects of the Corpus Allatum Hormone in the Male Desert Locust
Authors: Odhiambo Thomas R.
Published: April 2021

An account is given of the normal pattern of total lipid content of male desert locusts from the time of adult emergence to the time the locusts are approaching senescence (18—25 days). Up to the seventh adult day, there is a rapid increase in the amount of body lipids ; thereafter, there is a progressive depletion of lipid reserves. Allatectomy of the locusts soon after adult emergence leads to considerable accumulation of lipids which becomes apparent when the locusts attain sexual maturity and persists thereafter. Gonadectomy or mere wounding has no such effects. Implantation of active corpora allata in previously allatectomized locusts reverses the tendency to lipid accumulation.
Asymmetry of the Motor System in the Hermit CrabPagurus GranosimanusStimpson
Authors: Chapple William D.
Published: April 2021

The decalcification of the abdomen and the asymmetry of the central flexors is a ‘hydrostatic’ mechanism by which the abdomen is expanded to fit the shell tightly. The single pair of giant fibres is homologous to the medial giants of the crayfish except that no contralateral activation of the flexor muscles was observed. Two kinds of asymmetry in the motor system were observed; (a) loss of motor fibres in the first ganglionic roots of the right side; (5) greater frequency of ‘spontaneous activity’ in the slow flexor branch of the third roots on the left side. Sensory stimulation evoked different sets of fibres in these third root branches; one set fired spontaneously even after total ganglionic isolation, the other, when reflexly activated, reciprocally inhibited the first group. Antidromic and synaptic inputs failed to re-set the spontaneous activity; two kinds of reflex activation, phasic and tonic suggest two different sites for inputs, one to the motoneurons, the other to a pre-synaptic pacemaker. Alternations of the two reflex groups occurred in the totally isolated ganglion; addition of picrotoxin to the saline abolished reciprocal inhibition but variations in the frequency of spontaneous activity persisted. A possible mechanism for this system is proposed.
Changes of Internal Hydrostatic Pressure and Body Shape in Acanthocephalus Ranae
Authors: Hammond R. A.
Published: April 2021

Two hydraulic systems are primarily concerned in the movements of Acanthocephalus ranae (Schrank, 1788; Lühe, 1911), that of the proboscis apparatus and that of the trunk (Hammond, 1966a). The muscles associated with each system operate about a fluid skeleton of constant volume. Muscular activity in either system, and therefore change of body shape, is accompanied by a change of hydrostatic pressure within the skeletal fluid.
The Balance Between Antagonistic Induction and Depression of Flight Activity in Aphis Fabae Scopoli
Authors: Kennedy J. S.
Published: April 2021

A bout of settling activity on a leaf or other surface has both excitatory and inhibitory effects upon subsequent flight activity (antagonistic induction and depression of flight by settling); flight has similar after-effects upon settling; and the changing balance between these reciprocal after-effects determines the general course of behaviour. The strength and duration of settling responses made on landing by free-flying aphids were regulated by jolting them off the surface into flight again prematurely. This treatment diminished but did not otherwise appear to distort the after-effects of a landing on flight and was used to establish the following points. The balance between the excitatory and inhibitory after-effects of any one landing on flight depends (i) on the excitatory states of both flight and settling before the landing occurs, and (ii) on the strength of the settling stimuli received from the surface after landing. The after-effects of settling on flight are predominantly excitatory when flight is already strong relative to settling but predominantly inhibitory when flight is relatively weak; the after-effects of strong settling are consistently greater, both ways, than those of weak settling. Landings on different surfaces known to provide weak and strong settling stimuli still produce their typically different after-effects on flight when the settling responses actually performed on the two surfaces are kept equal. The after-effects of settling on flight evidently do not require any peripheral feed-back (although this can add to the after-effects), and result from central cross-inhibition of flight when settling is centrally excited by external stimuli.
The Supply of Oxygen to the Active Flight Muscles of Some Large Beetles
Authors: Miller P. L.
Published: April 2021

Measurements of the wing-beat frequency, wing-stroke amplitude and stroke plane and of abdominal ventilation have been made during the tethered flight of twenty-six species of beetles belonging to five families, mainly in Uganda. Abdominal ventilation is weak or absent in all species of Cerambycidae, Elateridae and Anthribidae examined in flight. The tracheal system in these families is characterized by the complete absence of air sacs, and in larger species by the presence of four giant trunks running through the metathorax between spiracles 2 and 3 and forming the primary supply to the flight muscles. Abdominal ventilation is strong during the flight of all species over o·6 g. in weight of the Scarabaeidae and Buprestidae which were examined. Their tracheal systems contain an abundance of air sacs while giant trunks are absent. Measurements of the thoracic volume changes which accompany each wing beat show that the amount of air which can be pumped in this way increases in larger Cerambycidae per second per gram as compared with small species. Large Cerambycidae pump more per gram than Scarabaeidae of comparable size. During the flight of the cerambycid Petrognatha the thoracic pump exchanges 540 μ1. air/sec./g. Its action is mainly on the compressible secondary tracheae. In a wind speed of 5 m./sec. 1050 μ1. air/sec./g. are driven through the four giant trunks, entering through spiracle 2 and leaving from spiracle 3. The trunks are stout-walled and probably unaffected by the thoracic pump.
The Mobilization of the Calcium Carbonate Deposits in the Endolymphatic Sacs of Metamorphosing Frogs
Authors: Pilkington J. B. , Simkiss K.
Published: April 2021

Tadpoles of Rana temporaria have been reared in solutions of high and low pH with and without calcium. Methods have been devised for analysing calcium, carbonate and phosphate in individual tadpoles. From these analyses it is possible to determine the distribution of calcium salts between the endolymphatic sacs and the skeleton throughout metamorphosis. A system has been devised for correlating biochemical data with the morphological changes occurring during metamorphosis by means of a scale of ‘developmental days’. The resorption of the endolymphatic deposits is not influenced by the acidity of the environmental solution. Tadpoles reared in solutions containing added calcium had at any one stage in metamorphosis a larger reserve of endolymphatic calcium and a better ossified skeleton than the other tadpoles. During metamorphic climax, when the tadpoles do not feed, the calcareous material in the endolymphatic sac is resorbed to provide calcium for the ossification of the skeleton and to make good any renal loss of calcium. The resorption of endolymphatic calcium carbonate occurs in all tadpoles during metamorphic climax irrespective of the level of calcium in the environmental water. The otoliths do not appear to be resorbed and the spinal portion of the deposits in the endolymphatic sacs may be more labile than those in the cranial regions.
Maternal Induction of Diapause in the Larva of Lucilia Caesar L. (Diptera: Calliphoridae)
Authors: Ring R. A.
Published: April 2021

The seasonal pattern of diapause incidence in Lucilia caesar L. shows that diapause in the 3rd-instar larvae of field-captured females increases rapidly during the month of July. By rearing and testing all larvae under standard laboratory conditions confirmation has been given to the hypothesis that this sudden increase, which occurs soon after the summer solstice, is due to a maternal influence. It has been shown that photoperiod is the most important factor controlling this maternal influence, with temperature playing a modifying role in the photoperiodic response. Females do not respond to the intrinsic rate of change in the photoperiod, but to the absolute levels of the light/dark phases. Long photoperiods (20 hr.) tend to avert, and short ones (12 hr.) tend to induce, larval diapause. Thus L. caesar is another example of a ‘long-day’ species as described by Lees (1955). Under laboratory conditions there is a time lag of 8-10 days before a change in the absolute length of the photoperiod acting on the mother reflects its diapause influencing effect on the larvae. Maternal ageing produces an increase in larval diapause incidence after 6-10 weeks. It is not yet known whether or not the maternal influence is hormonal in character.
Further Studies on the Electrophysiological Anatomy of the Left and Right Giant Cells in Aplysia
Authors: Hughes G. M.
Published: April 2021

Electrophysiological studies on cells of Aplysia central ganglia have become of general interest in recent years and have developed from work on the nature of integrative mechanisms (Arvanitaki & Chalazonitis, 1959; Tauc, 1955; Tauc & Hughes, 1963) to investigations of plastic change at a cellular level (Bruner & Tauc, 1966; Kandel & Tauc, 1965). Earlier work showed the range of phenomena found in a variety of cells, particularly in the abdominal ganglia, but research has now become more concentrated on certain cells which are readily identifiable in all preparations (Strumwasser, 1965 ; Hughes & Tauc, 1961 ; Kandel & Tauc, 1965). Of these cells, the large cell in the right upper quadrant, which is often called the giant cell, or right giant cell (RGC), has been used a great deal in studies on the basic phenomena of spike initiation in molluscan cells (Tauc, 1962). The anatomy of this cell was shown to be quite complex as a result of electrophysiological studies (Hughes & Tauc, 1963) which also revealed the presence of a comparable cell (LGC) on the left side of the C.N.S. Because of similarities in the general pattern of branching of these cells, they were considered homologous.
Relationships Between Photoperiodism and Circadian Rhythms of Activity in the House Finch
Authors: Hamner W. M. , Enright J. T.
Published: April 2021

The Büuning hypothesis proposes that many rhythmic physiological processes, including photoperiodic responsiveness, are all based upon a single, endogenous circadian time-measuring system (‘die physiologische Uhr’). We have attempted to test this hypothesis by examining correlations between the circadian waking-sleeping rhythm of the house finch (Carpodacus mexicanus), and the circadian rhythm of sensitivity to light, which underlies the photoperiodic testicular responses of this species. Experimental techniques included (1) comparisons of locomotor activity patterns induced by specific non-daily light cycles which stimulate gametogenesis (LD 6:30 and 6:54) with those induced by other cycles which are non-inductive (LD 6:18, 6:42 and 6:66); (2) comparisons of gametogenesis resulting from light cycles which produce large phase-lead in the activity rhythms and thereby result in photic stimulation late in the ‘subjective day’ (LD 6:20 and 3:23) with results from similar cycles which cause no phase lead (LD6:i6 and 3:19); and (3) comparisons of gametogenesis under free-running (unsynchronized) conditions in which a 6 hr. stimulus was intermittently administered early in the ‘subjective day’, with other treatments in which the same stimulus was administered late in the ‘subjective day’. In all experimental series, when only group responses are considered, there were clear and strong correlations between testicular growth and the patterns observed in locomotor activity. The nature of the large intra-group variability, however, convinces us that the Bünning hypothesis, as here interpreted, is inadequate to account for all the results. Either the two circadian rhythms may be independent, similar systems; or, if there is a single ‘master clock’, the two manifestations of this timing system are apparently not phase-locked under artificial laboratory conditions. It is not clear to us how these two alternatives are experimentally distinguishable.
The Roles of Sodium Transport and Anion Permeability in Generating Transepithelial Potential Differences in Larval Salamanders*
Authors: Dietz Thomas H. , Kirschner Leonard B. , Porter David
Published: April 2021

Recent investigation has shown that the fully aquatic, larval form of the salamander Ambystoma tigrinum handles osmotic and ionic regulatory problems as do other fresh water and semiterrestrial animals. Faced with osmotic water entry from a hypotonic environment, it excretes a dilute urine to remain in water balance. Uptake of NaCl from artificial-pond water occurs at the rate of about 1μ-equiv. (10 g.)−1hr.−1. This maintains an ionic steady state by compensating for losses in the urine and by diffusion across the skin and gills (Alvarado, 1962; Alvarado & Kirschner, 1963). Animals in a steady state in pond water ([NaCl] = 1·2 mM/1.) have a potential difference across the body surface of 10–20 mV., body fluids positive to the external solution. Nothing is known about the mechanism generating electrical asymmetry in these animals.
Changes in Blood Pressure in the Rainbow Trout During Hypoxia
Authors: Holeton G. F. , Randall D. J.
Published: April 2021

Methods for cannulating the ventral aorta of the trout, which permit the measurement of blood pressure in the unanaesthetized, unrestrained, intact fish are described. Rate and amplitude of breathing and blood pressure in the dorsal and ventral aortae increase during hypoxia. These changes are associated with a marked bradycardia. There are increases in vascular resistance to blood flow in both respiratory and systemic circulations during hypoxia. Post hypoxia is associated with large increases in ventral aortic and dorsal aortic pressures.
The Exchange of Oxygen and Carbon Dioxide Across the Gills of Rainbow Trout
Authors: Randall D. J. , Holeton G. F. , Stevens E. Don
Published: April 2021

The effectiveness of oxygen uptake by the blood of rainbow trout (Salmo gairdneri) approaches 100%, whereas that for the removal of oxygen from water was only 11-30%. Most of the carbon dioxide is removed from the blood as it passes through the gills, but the effectiveness of carbon dioxide uptake by water is very low, because of the high capacity of water for carbon dioxide compared with oxygen. Moderate exercise had little effect on the effectiveness of gas exchange across the gills. The increased oxygen uptake was facilitated by an increase in the transfer factor of the gills for oxygen. There were small increases in the capacity-rate ratio of blood to water at the gills during moderate exercise. Hypoxia resulted in a marked decrease in the effectiveness of oxygen uptake by the blood, but had little effect on oxygen removal from the water. Gas exchange was facilitated during hypoxia by an increase in transfer factor of the gills, but hindered by an increasing capacity-rate ratio of blood to water at the gills. Gas exchange in an aquatic environment was compared with that in an aerial environment.
Axonal Function and Ionic Regulation in the Central Nervous System of a Phytophagous Insect (Carausius Morosus)
Authors: Treherne J. E. , Maddrell S. H. P.
Published: April 2021

Experiments using intracellular and extracellular recording techniques indicate that, despite the specialized ionic composition of the haemolymph, the axons in the nerve cord of Carausius are conventional in that the action current is largely carried by sodium ions. This effect is achieved by an appreciable regulation of the concentrations of inorganic ions in the extracellular fluid bathing the axon surfaces. The extra-axonal regulation does not appear to result from any significant restriction in the accessibility of cations to the general extracellular system, but from a local regulation which appears to maintain a relatively high concentration of sodium ions at the axon surfaces. It is suggested that such a regulation may be achieved by an extrusion of sodium ions from the glial cells into the restricted extra-axonal spaces demonstrated in the electron micrographs of this preparation.