bluuebunny/crossref_metadata_2025 huggingface dataset:
Central Mechanism of Hearing in Insects
Authors: Suga Nobuo , Katsuki Yasuji
Published: April 2021

The impulses from the tympanic organ are transmitted at the prothoracic ganglion to a central neuron, the auditory T large fibre, which lies in the cord between the brain and the metathoracic ganglion. The impulses in the T large fibre are conducted rostrally and caudally with the same discharge pattern. Information is sent up to the brain, and down to the metathoracic ganglion, after a delay of about 12 msec. The impulses from the cereal hair sensilla are transmitted to two similar auditory C large fibres which lie in the cord between the metathoracic and last (6th) abdominal ganglia and are then sent up to the mesothoracic ganglia by other auditory large fibres. Central inhibitory interaction between the impulses from the tympanic nerves of the two sides are shown by a marked increase of impulses in the T large fibre following section of one of the tympanic nerves. No inhibitory interaction is found between the impulses from the two cereal nerves. The auditory T large fibre receives not only the excitatory effect from the ipsilateral tympanic nerve at the prothoracic ganglion, but also the inhibitory and weak excitatory effects from the contralateral one. The response range of the T large fibre is narrower than the threshold curve of the tympanic nerve and corresponds with one type of response range in the tympanic neurons. The response ranges of the C large fibres correspond closely with the threshold curve of the cereal nerve. A large difference in threshold between the two T large fibres is found in the response to sound incident from the side. The number of impulses in the T large fibre nearer to the sound source is greater than in that farther from the source. The difference in the number of impulses between the two T large fibres is most marked in the response to sound of the frequency which is dominant in stridulation. This difference is due to the mutual inhibitory interaction of neurons which modifies the number of impulses without changing the threshold of the tympanic large fibre. It is suggested that the central inhibitory interaction increases the information about a sound source and plays an important role in the mechanism of the directional sense. The stridulation of the group activates the tympanic nerve and evokes synchronized discharge in the T large fibre, but scarcely at all in the primary C large fibre. The tympanic organ and its neural network seem well adapted to reception of stridulation. It is concluded that though neither of the two sound receptive organs—the tympanic organ and the cereal hair sensilla—can perform frequency analysis, the insect may be able to do so by making use of both organs, since they have different frequency ranges and are served by different auditory large-fibre tracts.
The Annual Growth-Rate Cycle in Brown Trout (Salmo Trutta Linn.) and Its Cause
Authors: Swift D. R.
Published: April 2021

A regular annual growth-rate cycle is demonstrated in wild and hatchery yearling brown trout; the fish have a high growth rate in the spring and autumn and a low growth rate during the summer and winter of each year. Experimental work with constant-environment aquaria, together with the results of the field work, indicate that the water temperature is the main external environmental factor influencing the growth rate. Maximum growth rate is achieved at 12°C. The reason for the fall in growth rate above 12°C. is discussed and it is suggested that inadequacy of the respiratory system of the fish is the prime cause.
The Urine of Gammarus Duebeni and G. Pulex
Authors: Lockwood A. P. M.
Published: April 2021

A study has been made of the relation between blood, urine and medium concentrations in the two amphipod Crustacea G. duebeni and G. pulex. G. duebeni produces urine hypotonic to the blood but hypertonic to the medium when it is in media more dilute than 50% sea water. G. pulex forms urine which is hypotonic both to blood and medium when in 2−20% sea water. G. duebeni begins to form hypotonic urine within 2 hr. of transference from no to 160% sea water to fresh water. Hypotonic urine formation begins in these circumstances when the blood concentration is up to twice that at which hypotonic urine is formed by animals fully adapted to their medium. It is concluded (a) that the concentration of urine produced by G. duebeni is not dictated solely by the absolute level of the blood concentration; (b) that the formation of urine hypotonic to the blood in a brackish-water animal functions primarily as a means of conserving ions in the body ; (c) that the ability to regulate the concentration of the urine with rapidity will be important in an animal living in environments of fluctuating salinities.
The Efflux of Sodium Ions from the Last Abdominal Ganglion of the Cockroach, Periplaneta Americana L.
Authors: Treherne J. E.
Published: April 2021

The rate of loss of 24Na from the terminal abdominal ganglion of Periplaneta americana L. has been studied by measuring the decline in radioactivity associated with an isolated preparation maintained in flowing physiological solution. The rate of sodium efllux was substantially reduced in the presence of 0 · 2 mM./l. dinitrophenol and in potassium-free solution. The extrusion of 24Na was not significantly affected by the removal of the fibrous and cellular sheath surrounding the ganglion. The rate-limiting process in the efflux of sodium measured in the experiments was not, therefore, the transfer of ions across the nerve sheath, but an extrusion from tissues lying at a deeper level in the central nervous system.
The Kinetics of Sodium Transfer in the Central Nervous System of the Cockroach, Periplaneta Americana L.
Authors: Treherne J. E.
Published: April 2021

The exchange of sodium ions in the cockroach central nervous system has been studied by following the escape of 24Na from isolated abdominal nerve cords, single connectives and ganglia. Particular attention was paid to the initial rapid exchanges of sodium. The escape of sodium ions occurred as a two-stage process, an initial rapid phase eventually giving way to a slower exponential phase of sodium loss. The fast phase of efflux was not affected by the presence of 2:4-dinitrophenol, although this poison significantly reduced the second slow phase of sodium extrusion. The initial fast phase is attributed to a rapid diffusion from an extracellular space, demonstrated by 14C-inulin; the second phase is identified as the slower extrusion from the cellular components of the central nervous system.
Retinal Orientation and the Discrimination of Polarized Light by Octopuses
Authors: Rowell C. H. Fraser , Wells M. J.
Published: April 2021

The object of the investigation was to show that the ability of Octopus to detect the plane of polarization of light does not depend upon differential reflexion from its surroundings. Animals were trained to distinguish between light plane polarized in the vertical plane (normal to the iris slit of the intact animal) and in the horizontal plane (parallel to the slit). The statocysts were then removed, abolishing the normally fixed orientation of the eyes with respect to gravity. After the operation the plane of polarization was set at each trial so as to be either normal or parallel to the iris slit. Because the eyes were now disoriented, there was no longer any constant relation between these planes and the fixed reflecting surfaces of the aquarium. The animals, nevertheless, continued to discriminate correctly. It is therefore concluded that detection of the plane of polarization depends upon some intra-ocular mechanism.
The Uptake and Distribution of Water in the Embryo of Xenopus Laevis (Daudin)
Authors: Tuft P. H.
Published: April 2021

Water is the only constituent of the amphibian embryo that is taken up from the environment in appreciable quantities during the course of development, and at hatching it occupies nearly three times as much space in the embryo as all the other constituents combined. In spite of its small molecular size, however, and its ability to diffuse freely throughout the embryo, water is not uniformly distributed nor is its distribution constant. During the early stages of development, large liquid-filled spaces with low solid content—the blastocoel and archenteron—form between the cells, increasing and decreasing in volume as development proceeds; and although amphibian embryos normally develop in an environment which contains little or no solutes, they can tolerate a wide range of external osmotic pressures. Factors which control the uptake and distribution of water in the embryo may therefore be expected to play an important part in growth and morphogenesis. The experiments described in this paper were undertaken to obtain quantitative information on which to base a study of these factors, in the embryo of Xenopus laevis (Daudin).
The Effect of Resorbing Eggs Upon the Sex Ratio of the Offspring in Nasonia Vitripennis (Hymenoptera, Pteromalidae)
Authors: King P. E.
Published: April 2021

Nasonia vitripeinnis is parasitic on the pupae of various muscoid flies. It has a haplo-diploid system of sex determination (Berland, 1951; Whiting, 1954), fertilized eggs producing females and unfertilized eggs males. Provided that host puparia are available continuously to the parents, the diploid females outnumber the haploid males in the ratio of 3:1. A possible mechanism for determination of this ratio has already been suggested (King, 1961). Previous work has demonstrated that the environment has a profound effect upon the sex ratio of the Hymenoptera. Clausen (1939) stated that the sex ratio varied with the sex ratio of the host, with successive generations upon the same or a different host or with different species of host, or according to whether the host population was increasing or decreasing. Chewyrew (1913), Holdaway & Smith (1932), Seyrig (1935), Taylor (1937) and Ullyet (1936) said that the proportion of males in a population depended upon the size of the host; in a small host the proportion of males was higher. Flanders (1937) working on Metaphycus stated that if the hosts were less than 1 mm. long only males were produced; the proportion of males decreased with an increase in size of the host. Whiting & Anderson (1932) working on Habrobracon, Flanders (1938) working on Tetrastichus and Wilson & Woolcock (1960) showed that the temperature affected the sex ratio.
Unit Activity in the Abdominal Nerve Cord of a Dragonfly Nymph
Authors: Fielden Ann , Hughes G. M.
Published: April 2021

Electrical activity of single units has been studied in small bundles of nerve fibres split off from the connectives between abdominal ganglia of the dragonfly nymph. Many units showed a resting discharge but activity of other units was only found when the insect was stimulated mechanically. In some fibres the resting discharge was unaffected by mechanical stimulation and such spontaneous activity showed different patterns. These units were identified as intemeurones and a prominent feature of their discharge was an irregular firing over long periods and the formation of characteristic intermittent bursts. Responses to tactile or proprioceptive stimulation were investigated in primary sensory fibres and intemeurones. The latter showed excitatory and inhibitory effects which were often related to the site of the peripheral stimulus. Primary sensory fibres generally gave action potentials of smaller amplitude and were excited by stimulation of more localized areas. Many fibres traverse at least one connective after they enter a segmental ganglion and most ascend or descend ipsilaterally, but some crossing-over of sensory fibres occurs in the ganglia. Intemeurones were classified according to the nature of the peripheral areas from which they received their input. Ipsilateral, contralateral, and bilateral fibres have all been found but so far there is no evidence for any asymmetric fibres. Fibres responding to stimulation of a single segment or of many segments were found. Some of the latter extended over the whole length of the body and it is clear that spikes may be initiated in many of the ganglia through which an interneurone passes. It is evident from this work that a given peripheral area is represented centrally by many intemeurones and a great deal of convergence from different areas may occur on individual intemeurones.
Peripheral Reflex Inhibition in the Claw of the Crab, Carcinus Maenas (L.)
Authors: Bush B. M. H.
Published: April 2021

Reflex opening of the claw of the crab, Carcinus maenas (or of the crayfish, Astacus pallipes), elicited by mechanical stimulation at the carpo-propodite joint, can be reflexly inhibited by stroking the inside of the claw. By electrical and mechanical recording from the opener muscle (the apodeme or motor axons of the antagonistic closer muscle being cut), and by electrical recording from the motor and inhibitor axons to this muscle, it is shown that this reflex inhibition is effected mainly peripherally, through the inhibitor axon specific to the opener muscle. Central inhibition of the motor axon plays at the most a minor part. The externally recorded action potentials of the opener muscle show strong peripheral inhibition of both the α (‘supplemented’) and β (‘simple’) forms (i.e. with and without attenuation of muscle potentials, respectively) during the reflexinhibitory stimuli, as well as sporadic attenuation at other times. Attenuation of a muscle potential results, in Carcinus claw opener, when an inhibitor impulse precedes the motor impulse by less than 15-20 msec., and is maximal when this interval is less than approximately 5 msec. Thus α inhibition predominates over β inhibition at the higher frequencies of discharge. The frequency of impulses in the opener motor axon commonly ranges from 20 to 80/sec. with brief bursts of 80-200/sec. during reflex contraction of the opener muscle, and does not fall significantly during reflex-inhibitory stimulation. The opener inhibitor, which often manifests an irregular low-frequency ‘background’ discharge during reflex opening, responds to concurrent reflex-inhibitory stimulation with a sharp increase in frequency to 100-200 impulses/sec. initially and falling to 50-100/sec. with continued reflex inhibition. Reflex-inhibitory stimulation alone elicits only inhibitor impulses. Following cessation of stimulation the tension declines ‘passively’. Owing to continuing motor activity, however, this decline is often slower than during active inhibition; it is often also erratic due to the occurrence of inhibitor impulses. When a relatively high ratio of inhibitor/motor impulse frequencies precedes a burst of motor impulses eliciting a rise in tension, the rate of this tension rise is lower than that excepted from the frequency of motor impulses evoking the rise. When there is a relatively high-frequency ‘background’ discharge in the opener inhibitor the tension in the muscle shows rapid fluctuations, whereas with lower inhibitor frequencies fairly steady tensions are sustained. This is in part because the peripheral latency of mechanical inhibition varies inversely with the ratio of inhibitor/ motor frequencies preceding the inhibition. It is suggested that a background of peripheral inhibition, by making possible quicker relaxation, may be an important factor in rapid movement.
The Mode of Action of the Corpus Cardiacum On the Hind Gut in Periplaneta Americana
Authors: Davey K. G.
Published: April 2021

Addition of a homogenate of corpora cardiaca to the fluid bathing an isolated hind gut of Periplaneta produces an increase in tonus, amplitude, frequency and co-ordination of contractions. The corpus cardiacum acts by stimulating cells in the upper colon to release an indolalkylamine. This amine acts on the mucles through a peripheral nervous system which can function in isolation from the central nervous system.
The Composition of Haemolymph in Aquatic Insects
Authors: Sutcliffe D. W.
Published: April 2021

Analyses were made of haemolymph obtained from aquatic representatives of nine major orders in the Insecta. In the Odonata, Plecoptera, Ephemeroptera and Hemiptera-Heteroptera, the sodium concentration is relatively high and the potassium concentration is low. The chloride concentration is relatively high, but it never exceeds the sodium concentration. In the Neuroptera, Coleoptera, Trichoptera and Diptera the sodium concentration is relatively high and the potassium concentration is low. In Nymphula nymphaeta(Lepidoptera) both the sodium and potassium concentrations are low. In all of these endopterygotes the chloride concentration is relatively low. There is no correlation between diet and the sodium/potassium ratio in haemolymph of aquatic insects. The problem of cation-anion balance is discussed. It is suggested that free amino acids contribute little to the anion pool. Bicarbonate and phosphate, largely as inorganic phosphate, contribute a small amount to the anion pool in exopterygotes. Phosphate contributes considerably more to the anion pool in some endopterygotes. Nevertheless, in all of the insects investigated, there is a deficit of anions. This deficit is usually greater in the endopterygotes. The calculated osmotic activities of the known ions and free amino acids are less than the observed osmotic activities of haemolymph. It is inferred that non-amino organic acids must be present. Preliminary investigations indicate that non-amino acids are present in the concentrations required to account for both the osmotic and the anion deficits.
The Oxygen Uptake and Metabolism of Balanus Balanus Spermatozoa
Authors: Barnes H.
Published: April 2021

The spermatozoa of the Crustacea are often atypical, bizarre, and non-flagellated; those of the few species of cirripedes so far investigated are filamentous bodies in which a much elongated nucleus lies lateral to the fibrillar bundle over much of the length of the latter (unpublished work). When ripe spermatozoa of Balanus balanus (L.) Da Costa are teased out of a seminal vesicle into sea water, their movement is usually negligible and certainly in marked contrast to that of many other invertebrate spermatozoa. B. balanus is a hermaphrodite, yet cross-fertilization is obligatory ; the spermatozoa are transferred to the functional female in a copulatory act, after which the operculum tends to remain closed, the animal assuming a quiescent state with little cirral activity. The semen is shed in the form of a white sticky mass which at first has relatively little tendency to disperse in sea water; the semen thus tends to remain within the mantle cavity. Under natural conditions the details of fertilization are difficult to observe but it would seem that the eggs are only brought into the mantle cavity as the result of some stimulus associated with copulation.
Anaerobic Heat Production and Fructolysis of Bull Spermatozoa at Different Temperatures
Authors: Rothschild Lord
Published: April 2021

The anaerobic heat production and fructolysis of bull spermatozoa has been measured at 37°, 27°, 17°and 7° (heat production only) C. Between 37° and 27°, 27°and 17°, and 17° and 7° C. the mean temperature coefficients of heat production were 4·07, 3·23 and 8·92 during 90 min. incubation. Between 37°and 27°, and 27° and 17° C. the mean temperature coefficients of fructolysis were 3·00 and 3·15 during 90 min. incubation. The differences between the comparable values given in (2) and (3) are not statistically significant. The temperature coefficient of the impedance change frequency of bull semen was 5·14 in one experiment and 4·17 in another. There were no impedance changes at 17°C.
The Imaginal Ecdysis of Blowflies. Evidence for A Change in the Mechanical Properties of the Cuticle at Expansion
Authors: Cottrell C. B.
Published: April 2021

Experiments in which blowflies (with proboscis and anus blocked at emergence) were subjected to artificial pressures of 7 cm. Hg. show that expansion is possible only during the period when air-swallowing movements occur. At this time there is a change in the mechanical properties of the cuticle which is confined to the presumptive sclerite areas and enables them to expand. Before and after air-swallowing application of identical artificial pressures merely results in the temporary distension of membranous areas and in the unfolding of the wing membrane (but not the expansion of the wing veins which are presumptive sclerite areas). Prior to the cessation of air-swallowing, unfolding of the wing membranes under artificial pressure takes place without separation of the upper and lower lamellae, but after cessation, unfolding is usually accompanied by ‘bladdering’ of the wings, which become converted into blood-filled sacs.
Observations On the Myo-Neural Physiology of the Polyclad, Planocera Gilchristi
Authors: Gruber Sheila A. , Ewer D. W.
Published: April 2021

Planocera gilchristi Jacubowa is a large polyclad worm which occurs between tide marks off the south coast of Africa. It may be kept easily in the laboratory. Our knowledge of the physiology of neuromuscular systems of the triploblastic acoelomates is meagre and Planocera appeared to be a suitable animal for experiment for its nerves may be readily seen by transmitted light, and it quickly recovers from any operative treatment.
The Cicada Song
Authors: Nakshbandi M. , Zahlan A.
Published: April 2021

The song of the cicada (genus : Cicadatra) has been studied. The wave-form of the song shows two modes of amplitude modulation: (a) a slow modulation, period 8·3 msec; (b) a fast modulation, 40–75 μsec. growth and 185–250 μsec. decay. There is indication of wave distortion and instability at the beginning and end of the song.
Intrinsic Vasomotion in the Dogfish Gill
Authors: Satchell G. H.
Published: April 2021

It has been reported that fish may match the extent of their respiration to their need for gaseous exchange by failing to ventilate certain gills. One third of the respiratory movements of the lamprey (Lampetra fluviatilis), when in oxygenated tap water, consist of contractions of the anterior two or three branchial chambers only. In partially deoxygenated water the anterior five and finally all of the branchial chambers become active (Wikgren, 1953). In Raja batis water is taken in through the spiracles during rest and perfuses only the anterior four gill pouches. When swimming, water enters through the mouth as well and perfuses the posterior gills (Darbishire, 1907). The dogfish Scyliorhinus canicula has a similar division of the spiracular and buccal inflows between the anterior and posterior gills (Hughes, 1960). In the eel, van Dam (1938) reports that during rest only the gills of one side may be ventilated.
Simultaneous Shape Discrimination in Octopus After Removal of the Vertical Lobe
Authors: Muntz W. R. A. , Sutherland N. S. , Young J. Z.
Published: April 2021

In all previous investigations of the effects of vertical lobe removal on the discrimination of shape by Octopus, the animals were trained with the shapes presented successively, i.e. they were trained to attack one shape (the positive) when presented on its own, and not to attack another (the negative) when presented alone. Under these conditions, animals lacking the vertical lobes can learn to perform above chance with easy visual discriminations, but post-operative performance is much poorer than in unoperated controls whether animals are trained before or after the operation (refs, in Young, 1961). Animals are very severely impaired on a difficult discrimination, and may indeed give no evidence of learning. Some findings suggest that the poor performance is partly due to fluctuations in the tendency to attack that result from removal of the vertical lobes; thus operated animals tend to take any shape shown immediately after having been fed (whether it is positive or negative) and tend not to take any shape shown after receiving a shock.
Preparation for Flight by Hawk-Moths
Authors: Dorsett D. A.
Published: April 2021

Moths belonging to the family Sphingidae are not capable of controlled flight until the temperature of the flight muscle has been raised by a preliminary period of vibrating the wings. The flight-temperature of forty-five specimens of Deilephila nerii varied between 34 and 45° C., but individuals always flew at the same temperature. The temperature inside the thorax rose at a mean rate of 4·2° C./min. Alteration of the ambient temperature affects the duration of the warming period but not the flight-temperature. The flight-temperature shows a positive correlation with the wing loading. In Deilephila and two other genera of similar dimensions, an increase of 50 mg. in the wing loading corresponds to a rise of 5 ·75 ° C. in the flight-temperature. A method of measuring the rise in wing-beat frequency during the warming period is described. The thoracic temperature increases linearly with the frequency. It is concluded that the frequency of the wing beat is determined principally by the wing loading, whilst variations in the other parameters of the wing stroke provide the ‘fine control’ of flight regulation required during flight and whilst hovering.
Olfactory Stimuli and Oviposition in the Blowfly, Phormia Regina Meigen
Authors: Wallis D. I.
Published: April 2021

The work described attempts to elucidate the sensory mechanisms involved in the act of oviposition. A brief account of the morphology of the ovipositor and the distribution of the various sensilla on it is given. Behavioural experiments have shown unequivocally that receptors on the anal leaflets of the ovipositor are olfactory and can mediate oviposition. Flies are able to discriminate when antennal, palp and labellar receptors are blocked, but not when the ovipositor pegs are waxed over as well. A method for waxing the latter is described. Sensilla on the antennae, labellum and ovipositor perceive the olfactory stimuli which are important in inducing oviposition. Possibly there are olfactory receptors at other sites which mediate other types of behaviour. Tactile stimuli perceived mainly through sensilla on the ovipositor can play an important role in egg distribution and a minor role, possibly, in inducing oviposition. All the evidence suggests the pegs are the olfactory receptors on the ovipositor which mediate oviposition. A summary of factors known or suspected to influence oviposition is given.
On The Nervous Control of the Velar Cilia of the Nudibranch Veliger
Authors: Carter G. S.
Published: April 2021

(1) The beat of the velar cilia of the Nudibranch veliger is intermittent and appears to be under the control of the organism. (2) Fibres lying between the cells which bear the velar cilia are described. They end near the outer surface of these cells in fibrils which resemble those of the muscle-plate in structure. They stain with specific nerve-stains and were shown to be in all probability continuous with nerves lying deeper in the tissues. It is concluded that these are nerve-fibrils. (3) Within the ciliated cell at the level of the terminal fibrils of these fibres there is a layer of granules which stain with methylene blue. (4) The cilia of cells which have been separated from the tissues beat actively but the beat is continuous and not intermittent. (5) In the presence of various narcotics the intermissions are inhibited more quickly than the beat of the cilia is affected and at a lower concentration of the drug. (6) Some drugs which are not known to act as narcotics were used and with certain exceptions, which are discussed, did not have this effect. (7) In an acid medium the beat is slower but the intermissions continue so long as the cilia beat. (8) In an alkaline medium the intermissions are inhibited before the beat is affected. This is discussed and it is suggested that it is in accordance with recent work on the effect of changes in the reaction of the medium on nerve-tissue. (9) It is concluded that the nerve-endings found among these cells are regulatory and are concerned in the causation of the intermissions. The beat of the cilia is therefore under the control of the nervous system of the animal.
The Hydrogen-Ion Concentration of Natural Waters, I. the Relation OfpH To The Pressure Of Carbon Dioxide
Authors: Saunders J. T.
Published: April 2021

The evidence that the variations which occur in the hydrogen-ion concentration of a natural water have any direct effect on the inhabitants living under natural conditions is scanty and not very convincing. On the other hand, there is good evidence to show that many animals are tolerant of the changes in hydrogen-ion concentration of their native habitat. These variations can hardly be related to distribution, epidemics of conjugation and the like, for these are known to occur at very different values of the hydrogen-ion concentration. Occasionally it can be shown that the variations are sufficiently extreme to cause the total extinction of certain species, but this will only be in very small pools. It is true, of course, that profound changes can be produced in biological reactions in the laboratory by altering the hydrogen-ion concentration of the medium in which the reaction is taking place, but these changes are nearly always greatly in excess of the natural changes occurring in the normal environment. It appears to me that the real importance of the measurement of the hydrogen-ion concentration of a natural water is that it can be used as an accurate measure of the carbon dioxide produced by the animals and of the photosynthetic activity of the plants. But to use the measure of the hydrogen-ion for this purpose we must know something of the underlying principles involved in the measurement and must not merely be content with matching the colour produced by the addition of an indicator with the colour of a buffer solution prepared by a rule of thumb method.
The Energy-Sources in Ontogenesis
Authors: Needham Joseph
Published: April 2021

Investigation of the ammonia content of the developing hen’s egg shows that though in absolute amount it steadily increases during incubation, in percentage of the embryonic weight it declines. The intensity of production of ammonia reaches its highest point on the fourth day, i.e. five days before that of urea production, and seven days before that of the production of uric acid. The absolute amounts of nitrogen excreted in the form of ammonia are so small, however, that the curve for protein combusted by 100 gm. of embryo each day is hardly affected, and rises to a peak between the eighth and ninth days. These results are compared with others already in the literature of chemical embryology, which seem to bear on the theory of recapitulation. They afford further support to the conception of an ontogenetic succession of energy-sources.
The Vitality of the Spermatozoa in the Male and Female Reproductive Tracts
Authors: Hammond John , Asdell S. A.
Published: April 2021

Methods and experiments are described for testing the length of fertility of the sperms in the male and female tracts of rabbits. The sperms may retain their fertility in the male tract up to 38 days, but in the female tract only up to 30 hours. In cases where the sperms had remained in the female tract for 24-30 hours before ovulation small litters were frequently produced; it is suggested that this is due to the end point of the vitality of the sperms falling within the limits of time during which the process of ovulation occurs. The bearing of these results on problems of fertility and sterility is discussed.
Temperature and Time of Development of the Two Sexes in Drosophila
Authors: Bonnier Gert
Published: April 2021

The time of development at 25° C. up to the moment of pupation is found to be for females and males respectively 116·62 ± 0·19 and 116·78 ± 0·20 hours. During the pupal stage the two times are 111·36±0·15 and 115·46 ±0·13 hours. At 30° C. the corresponding figures are (in the same order): 99·95 ± 0·49, 103·37 ± 0·43, 78·15 ± 0·50 and 84·26 ± 0·34 hours. These figures show that there is a statistical significance in the differences of the times of development of the two sexes for both the periods at 30° C. but only for the pupal stage at 25° C. It is pointed out that the fact that the longer time of male development as compared with female development at 25° C. is confined to the pupal stage, may be correlated with the other fact that the essential parts of the secondary sexual characters are developed during this stage. It is shown that there is a negative correlation between the pre-pupal and pupal times of development, indicating that the longer the first time is, the shorter is, as a rule, the other time and “vice versa. With the aid of statistical methods it is shown that the shortening of the time of development at 30° C. as compared with the time at 25° C. is much more pronounced for the pupal than for the pre-pupal stage. This last fact is discussed and it is emphasised that the ordinary methods of studying the influence of temperature on development are too rough to be of more than of a descriptive value, the only way of getting a deeper insight into the processes of development by temperature studies being the separate studies of a number of short intervals.
The Growth of Fish
Authors: Gray J.
Published: April 2021

In most studies of post-embryonic growth it is customary to accept the observed increment in the total mass of the organism per unit time as an index of growth. Davenport (1897) found, however, that the opening phases of development of the frog were characterised by a very rapid rise in the water content of the embryo whilst the dry weight during this period gradually decreased. He concluded from these facts that the process of early embryonic growth was of a different and more “passive” nature than the more “active” growth which later ensues. Passive growth was regarded by him and by others as some form of imbibition, whilst the subsequent “active” growth involved the conversion of organic substances into living tissue and so involved an increase in dry weight. In the case of terrestrial animals, however, it has been known for some time that with increasing age the percentage of water in the organism falls, and the recent figures of Murray (1926) show that this fall is detectable at a very early age. It must be remembered that Davenport’s figures apply to the whole larva which in its early stages is heavily charged with yolk, whereas Murray’s figures apply to the embryo alone.
Uterine Grafts
Authors: Hammond John
Published: April 2021

Foetal tissues were transplanted into the pseudo-pregnant uterus of the rabbit, a suitable position for such grafts owing to the raised nutrition of the uterus occurring in the early stages of pseudo-pregnancy. Several tissues particularly large amounts of cartilage and small quantities of epithelial tissue persisted and grew, the former undergoing ossification. The growth of these foetal tissues in the pseudo-pregnant uterus did not cause the corpus luteum of pseudo-pregnancy to persist or the mammary gland to thicken as in pregnancy. Since—(a) the foetal tissues only grew where they were attached to the muscle layer of the uterus, although every effort was made to attach them to the mucosa; (b) the parts of the grafts lying in connection with the mucosa were absorbed rather than nourished; and (c) the introduction of living foetal tissue failed to cause any further development of the deciduomata which were produced by cutting the pseudo-pregnant mucosa—it is suggested that normally the attachment of the foetus is caused by the active erosive (digestive) agency of the foetal trophoblast, a function which is absent in the cells of the foetus itself. It seems probable that just as the small deciduomata are formed as a response to a cut so the large maternal placenta is formed as a response to the continuous erosion by the foetal trophoblast.
A Note on Haemerythrin
Authors: Marrian Guy Frederic
Published: April 2021

The effect of change of temperature on the dissociation curve of oxyhaemerythrin is shown. The heat of combination between haemerythrin and oxygen has been calculated to be 10,350 calories per gramme molecule of oxygen. It has been shown that oxyhaemerythrin is only stable over a small range of pH. The pigment appears to be most stable at pH 8·0 and 9·0. Variation of hydrogen-ion concentration between pH 6·0 and pH 10·0 appears to have little effect on the dissociation curve of oxyhaemerythrin. Oxyhaemerythrin can be converted to a yellow “methaemerythrin” by the action of oxidising agents. The change occurs spontaneously at slightly acid hydrogen-ion concentrations. Attempts to show the presence of haem in the haemerythrin molecule have been unsuccessful. The nature of the purple colour produced by the action of concentrated H2SO4 on a solution of oxyhaemerythrin is discussed. Photographs of the absorption spectra of oxyhaemerythrin, methaemerythrin and the H2SO4 product of oxyhaemerythrin are shown.
The Relation OfSpirostomum AmbiguumTo The Hydrogen ION Concentration (Alkaline Range)
Authors: Jenkin Penelope M.
Published: April 2021

A recovery method is described for determining the survival time of Spirostomum ambiguum (Ehrenberg) major in solutions of different hydrogen ion concentration. The survival time is defined as the longest time for which the animals can remain in the solution of harmful hydrogen ion concentration and afterwards recover their normal appearance when transferred back to a solution, the hydrogen ion concentration of which is known to be harmless. The results are given of experiments carried out in two solutions both of which provided media of known hydrogen ion concentration, but allowed this factor to be controlled by entirely different substances. The solutions were : Palitzsch’s borax-boric acid buffer mixture diluted ten times with glass distilled water. Cambridge tap-water (-0042 N carbonates) containing regulated amounts of carbon dioxide in solution. These experiments showed that the hydrogen ion concentration was a very important factor in determining the survival time of Spirostomum in the medium. In media of pH 7·4 the Spirostomum survive indefinitely but in solutions of pH 9·4 they rapidly die after greater or less swelling, according to the osmotic pressure of the medium. The time of survival decreases with increasing alkalinity and between pH 9·0 and 7·6 it is inversely proportional to the hydrogen ion concentration. Between pH 7·6 and 7·4 the time of survival is not proportional to the hydrogen ion concentration and a very slight decrease in the hydrogen ion concentration at this point will cause a very considerable, and quite disproportionate, decrease in the time of survival. It is suggested that such a slight decrease in the hydrogen ion concentration of the water is the possible explanation of the very sudden disappearance of Spirostomum from ponds, where it was existing in very large numbers.

The destruction of the Spirostomum in media of greater alkalinity than pH 7.4 is probably due to the increase in alkalinity affecting the body wall in such a way that it becomes more permeable to water, the result, as observed, being that the animals swell up and eventually burst.
Humidity Reactions of Three Aquatic Amphipods, Gammarus Duebeni, G. Oceanicus and Pontoporeia Affinis in the Air
Authors: Lagerspetz Kari
Published: April 2021

It has been previously shown that the aquatic isopod Asellus aquaticus—when taken out of water—is able to select the higher of two different humidities of the air (Lagerspetz & Lehtonen, 1961). In that connexion, it was suggested that some aquatic amphipods, when exposed to air, would probably also exhibit behavioural reactions to differences in atmospheric humidities.
The Effect of Temperature on Locust Flight Muscle
Authors: Neville A. C. , Weis-Fogh Torkel
Published: April 2021

In a recent study of the motor activity in relation to the wing movements of flying desert locusts, muscle action potentials were used to indicate mechanical activity of single motor units and also to demonstrate the motor repertoire of the central nervous system at the unit level (Wilson & Weis-Fogh, 1962). In order to do this it was essential to know exactly how the recorded potentials are related to the mechanical response at the relatively high thoracic temperature of flying locusts, 30–42° C. ; this information is provided here. During flight at medium intensity most muscles are fired a single time per stroke cycle and the movements are based upon ordinary twitch activity, but in some control reactions and during more powerful flight, D. M. Wilson discovered that locusts often make use of double firing, i.e. a unit is fired by two closely spaced action potentials (in the locust normally 4–8 msec.). In cases where the tetanus : twitch ratio is higher than unity this can obviously result in more force and power and he suggested that this may provide an important control mechanism in such systems which operate essentially on a twitch basis (Wilson, 1960). It was therefore of interest to investigate the mechanical effect of double firing.
The Relation Between Stimulus Parameters and Current Flow Through Stimulating Electrodes
Authors: Rowell C. H. Fraser
Published: April 2021

The flow of current through a small metal electrode, such as is commonly used in stimulation experiments, has been studied. The wave-form resulting from rectangular voltage pulses has been examined with various electrodes, preparation impedances and analogue networks. Variation of pulse repetition rate, when all other parameters are constant, causes wide variation of current flow and lesser variation of wave-form. An attempt has been made to relate these changes to physical changes occurring at the electrode tip during polarization of the electrodes. Calculations indicate that the amount of gas generated by the currents commonly used in stimulation experiments would produce gross distortion of the tissues in the absence of diffusion, and may do so in practice when large currents are used. It is concluded that changes of threshold with changes of pulse repetition rate are as likely to be due to the physical effects described here as to the physiological characteristics of the stimulated nervous system, to which they have sometimes been ascribed.
Some Factors in the Activation of Crab Movement Receptors
Authors: Mendelson Martin
Published: April 2021

The activation of movement receptors in Pachygrapsus crassipes is examined. Lengthening and shortening of the elastic strand of the propodite-dactylopodite (PD) organ are respectively the adequate stimuli for movement receptors responding uniquely either to closing or opening. These stimuli are also effective on the isolated PD organ. Twisting of the strand is without effect. Intracellular records from the receptor cells show apparent intermittent generator potentials during effective stimulation. No electrical activity is observed at subthreshold speeds or during movement in the inappropriate direction. The action potentials are initiated in the distal process at a considerable distance from the soma. Nicotine applied to the PD organ in high concentration elicits spike discharges of high frequency and long duration; it has no effect when applied to the axons. Applied to the PD organ in low concentration it potentiates the effect of mechanical stimulation without itself eliciting spikes. These findings are discussed in relation to the structure of the receptor endings and a mechanism is tentatively suggested to account for the unidirectional sensitivity.
The Filter-Feeding of Artemia
Authors: Reeve M. R.
Published: April 2021

The rates of filtration and of ingestion have been studied in Artemia of different ages feeding on pure cultures of plant cells of three different species, the concentrations of cells being varied over two orders of magnitude. The animal is capable of regulating its rate of feeding in such a way that, as the cell concentration increases, the filtration rate maintains a constant maximum value while the ingestion rate increases. When the concentration reaches a value at which a constant maximum ingestion rate is attained, the filtration rate falls off. In older animals the maximum ingestion rate is reached at a lower cell concentration than in younger animals. The maximum filtration rate is independent of cell size. The maximum ingestion rate is inversely related to cell size, the total volume of cells ingested being the same for three species of plant cells. The means whereby the animal maintains a maximum rate of total volume of cells ingested per unit time, irrespective of their size, has been investigated and is discussed.
Negative Pressures Produced in the Pharyngeal Pump of the Blood-Sucking Bug, Rhodnius Prolixus
Authors: Bennet-Clark H. C.
Published: April 2021

The sucking pump of Rhodnius drives blood from the host into the abdomen at a rate of up to 20 mm.3/min. The stylet canal is 8–10 μ diameter at the apex and the rate of taper is not more than 1 μ increase in diameter/100 μ length. The pressure required to force water through such a tube at that rate is about 2 atmospheres. The pressure required with blood would be higher. The musculature of the pump is theoretically capable of exerting a force on the pump piston of at least 2·5 atmospheres, while contracting at the required speed. The bug is capable of feeding at near to the normal rate when the surrounding pressure is 0·2 atmospheres and also against a pressure gradient of 0·2 atmospheres. The retreating contact angle of insect cuticle to a blood-air interface is very low. It is suggested that the high tensile strength of the blood and the low contact angle of the pump walls to the blood are the reasons why cavitation does not occur in the feeding pump of Rhodnius when the internal pressure drops below the vapour pressure of blood.
Excitatory and Inhibitory Pathways in the Arm of Octopus
Authors: Fraser Rowell C. H.
Published: April 2021

The octopus is an exceptionally strong, active and manipulative animal. The structure of the arms enables the animal to move over any sort of terrain, to apply a formidable grip or pull, to make most delicate movements, such as picking at tight knots in wet cotton until they loosen, to reach and clean any part of the body, or to make delicate sensory discriminations. The great learning ability of Octopus was first shown for visual problems by Young and Boycott and their school, but Wells and Wells have subsequently shown an equal ability to deal with tactile information from the arms (see Wells (1962) for reviews). The arms contain a large part of the central nervous tissue of the animal, with intrinsic sensory, interneural and motor elements, possess organized reflex systems, and are capable of quite a lot of autonomy. It is thus good material in which to study the lower organization of an invertebrate central nervous system.
Influence of Neurosecretory Cells and of Corpus Allatum On Intestinal Protease Activity in the Adult Calliphora Erythrocephala Meig
Authors: Thomsen Ellen , Møller Ib
Published: April 2021

The protease activity of the adult Calliphora female measured on the first 5 days after emergence was found to be highly influenced by the diet, the activity of females fed on sugar, water and meat (meat-flies) being much higher than that of females fed only on sugar and water (sugar-flies). The development of the enzyme(s) was found to be controlled by the medial neurosecretory cells (m.n.c.), the mean protease activity of females deprived of their m.n.c. only amounting to one-quarter to one-third of the maximum values for the meat-flies. Implantation of corpora cardiaca-allata (presumably containing m.n.c. hormone) into females without m.n.c. raised the protease activity of these significantly, showing that the influence of the implanted organs must be hormonal. The corpus allatum was found to have a certain, if minor, effect on the protease activity. It is concluded that in Calliphora the eating of meat exerts its effect on the production of protease mainly indirectly by causing liberation of m.n.c. hormone into the blood. As proteases are themselves proteins, the effect of the m.n.c. hormone on the production of proteolytic enzymes by the gut cells must be regarded as an effect on the specific protein synthesis of these cells. There is some evidence that the m.n.c. hormone might be involved in the regulation of protein synthesis in general.