bluuebunny/crossref_metadata_2025 huggingface dataset:
Soaring and Gliding Flight of the Black Vulture
Authors: Newman B. G.
Published: April 2021

The soaring and gliding performance of the black vulture has been analysed and the following conclusions are drawn. The wing span of the bird is altered in flight so that it may perform two tasks efficiently. First, that it may soar in rising currents of air for which a low sinking speed and thus a large wing span are required. Secondly, that it may penetrate into wind without undue loss of height for which a reduced wing area is desirable. Adjustment of the wing geometry towards the optimum soaring configuration is achieved by bending forward and opening the primary tip feathers. Since the airflow readily separates from the flat primary feathers at high angle of attack, these feathers, which are emarginated, are parted to form slots. The alula also presumably assists in delaying the flow separation over the primaries. It is unlikely that the opening of the primaries reduces the vortex drag.
The Effect of Vertical Lobe Removal On the Performance of Octopuses in Retention Tests
Authors: Wells M. J. , Wells J.
Published: April 2021

Octopuses were trained to make a tactile discrimination until they attained a criterion of either 75 % or 85% correct responses in twenty successive trials. They were then overtrained for an equal number of trials. Retention of training was tested in twenty unrewarded trials with the same objects 5 or 10 days later. Exactly similar experiments were made with animals trained after removal of the vertical lobes of their brains; these animals were slower to learn, but once trained to a similar standard of accuracy of response they forgot their training at the same rate as controls. This shows that while the presence of the vertical lobe enhances the effect of experience on the establishment of memories causing discrimination of things touched, it does not affect the maintenance of these memories once established.
Temperature Adaptive Behaviour in the Scorpion, Opisthophthalmus Latimanus Koch
Authors: Alexander Anne J. , Ewer D. W.
Published: April 2021

In discussing the possible functions of the pectines of the scorpion, von Ubisch (1922) suggests that they serve ‘um den Stigmen frische Luft zuzufuhren’ by their fanning movements or, alternatively, they prop up the mesosoma so that fresh air can reach the stigmata. Both of these suggestions imply that under conditions of respiratory stress a scorpion will lift its mesosoma clear of the ground so that the book-lungs have free access to air. Although von Ubisch did not apparently observe such behaviour, the recent report of ‘abdominal elevation’ in the Australian scorpion, Urodacus abruptus Poc. (Southcott, 1955) lends colour to such an hypothesis, although work on the functions of the pectines makes it seem very improbable that they actually serve as ‘respiratory fans’. Southcott gives an illustration of a female of U. abruptas in the attitude typical of ‘abdominal elevating behaviour’, and from a comparison of this with some of the stances observed in various South African scorpions it becomes clear that such behaviour occurs also in the latter. Opisthophthalmus latimanus Koch, O. nitidiceps Poc., O. austeras Karsch., Parabuthus planicauda Poc. and Uroplectes triangulifer Thor, all show the pattern to varying extents, and it was felt that with so many species available for study, it would be profitable to follow up Southcott’s observations. Preliminary tests indicated that the biological significance of this phenomenon appeared to be the same in all these species, and the results described below refer particularly to Opisthophthalmus latimanus which has been most intensively studied.
The Relation of Oxygen Consumption to Body Size and to Temperature in the Larvae of Chironomus Riparius Meigen
Authors: Edwards R. W.
Published: April 2021

The oxygen consumption rates of 3rd- and 4th-instar larvae of Chironomus riparius have been measured at 10 and 20° C. using a constant-volume respirometer. The oxygen consumption is approximately proportional to the 0·7 power of the dry weight : it is not proportional to the estimated surface area. This relationship between oxygen consumption and dry weight is the same at 10 and at 20° C. The rate of oxygen consumption at 20° C. is greater than at 10° C. by a factor of 2·6. During growth the percentage of dry matter of 4th-instar larvae increases from 10 to 16 and the specific gravity from 1·030 to 1043. The change in the dry weight/wet weight ratio during the 4th larval instar supports the theory of heterauxesis. At 20° C., ‘summer’ larvae respire faster than ‘winter’ larvae.
A Quantitative Description of Protoplasmic Movement During Cleavage in the Sea-Urchin Egg
Authors: Hiramoto Y.
Published: April 2021

Quantitative information on the protoplasmic movement during cleavage is one of the most important desiderata in the study of cell division. Spek (1918) described the protoplasmic streaming during cleavage and emphasized the importance of the surface tension in the cell division, giving attention to the similarity of this protoplasmic streaming to the streaming within an oil drop dividing as a result of local difference in surface tension. Dan and his collaborators (Dan, Yanagita & Sugiyama, 1937; Dan, Dan & Yanagita, 1938; Dan & Dan, 1940, 1942, 1947; Dan, 1943; Dan & Ono, 1954; Ishizaka, 1958) reported a series of experiments in which the cortical movement during cleavage was followed by measuring the movement of kaolin particles adhering to the cell surface. The results obtained by Spek and by Dan provide qualitative information on the protoplasmic movements during cleavage. However, from their data it is neither possible to make a quantitative analysis of the protoplasmic movement nor to infer the correlation between cortical and endoplasmic movements in detail. In the present work protoplasmic (both cortical and endoplasmic) movement during cleavage of the sea-urchin egg is described in a quantitative fashion, in order to provide basic data for the study of cell division.
Acoustic Reflexion Experiments with Perch (Perca Fluviatilis Linn.) to Determine the Proportion of the Echo Returned by the Swimbladder
Authors: Jones F. R. Harden , Pearce G.
Published: April 2021

Measurements were made under controlled conditions to determine the contribution of the swimbladder to the reflexion of acoustic energy from the perch, Perca fluviatilis. The amplitude of the echo fell by 50% when the swimbladder was emptied; this was observed both when the dorsal surface and when the lateral surface faced the direction of the incident sound energy. The polar diagram of the fish with its natural swimbladder is similar in shape to that obtained with a false ‘Onazote’ swimbladder.
The Physical Properties of the Swimbladders of Fish Other Than Cypriniformes
Authors: Alexander R. McN.
Published: April 2021

No excess internal pressure, such as has been found in the Cypriniformes, could be detected in the swimbladders of seventeen species from other orders. The swimbladder wall in these fish exercises no appreciable constraint on chnges of buoyancy with depth. Determinations of sinking factor and swimbladder volume are reported.
Interaction Between Walking and Probing in Aphis Fabae Scop
Authors: Ibbotson A. , Kennedy J. S.
Published: April 2021

In experiments with apterous adult aphids walking on non-plant surfaces, rostrum protraction and probing of the surface were elicited by a variety of situations having the common effect of interfering mechanically with the normal pattern of locomotory movements. A uniform wax ridge which fitted the span of the aphid’s legs but afforded a poor grip to the tarsi and broke up the stepping rhythm, combined with an over head light, generated a cyclical alternation between walking and probing. When the uniform substrate was interrupted by some form of obstacle to locomotion further probes were elicited, and the more abruptly and completely locomotion was arrested, the more promptly these appeared. Visual stimulation (from black models of aphid size) and olfactory stimulation (from the aphids’ siphuncle wax) also caused walking aphids to stop and probe. Readiness to probe varied greatly with age and pretreatment. Aphids denied access to a host plant for 1-2 days probed more frequently at random in response to the substrate but less frequently at objects encountered. Walking and probing interact in the manner of antagonistic reflex systems, and the diverse types of stimulus which elicited probing may all have done so indirectly by first inhibiting locomotion.
Loss of Water by Excretion and Defaecation in the Tsetse Fly
Authors: Bursell E.
Published: April 2021

The water content of the blood meal of tsetse flies is reduced from 79 to about 55% within the first 3 hr. after feeding. The water which is abstracted from the gut contents serves to bring the tissues of the fly to full hydration, and any excess is excreted. The degree of dehydration of the gut content depends on the amount of blood taken, relatively more water being retained in partial feeds. The water content of faecal matter is about 75% in flies maintained at high relative humidity throughout the hunger cycle, only 35% in flies maintained in dry air. The difference reflects a saving of more than 30% of the total water reserves of the fly under conditions of desiccation.
The Source of Carbon Monoxide in the Float of the Portuguese Man-of-War, Physalia Physalis L
Authors: Wittenberg Jonathan B.
Published: April 2021

Carbon monoxide, 0.5-13 %, is found in the float gases of Physalia. Oxygen comprises 15-20 % of the total gas. Carbon dioxide is present in negligible amounts. The gas gland, pneumadena, is the site of carbon monoxide formation. L-Serine is the substrate for carbon monoxide formation. A strikingly large concentration of folic acid is found in the gas gland. It is suggested that carbon monoxide secretion serves to inflate the float of Physalia and that carbon monoxide is later slowly replaced by air through diffusion and exchange.
Inhibition and Rhythmic Activity of the Circular Muscles of Calliactis Parasitica (Couch)
Authors: Ewer D. W.
Published: April 2021

The responses to electrical stimulation of isolated rings of the column and pedal disk of Calliactis are described. Such rings make slow spontaneous contractions which are frequently rhythmical, the interval between contractions normally being 7-20 min. Continuous low-frequency stimulation inhibits spontaneous activity of rings from the pedal disk and also of fresh rings from more adoral regions of the column. Older rings from the mid-column respond to such stimulation by a tetanic contraction. The latency of response to electrical stimulation of pedal rings is of the order of 120 sec. This latency is not affected by stimulation frequency but is prolonged by increase in the number of shocks applied. Stimulation of a pedal ring at the onset of a contraction prevents the further development of this contraction, while stimulation as a contraction reaches its maximum is followed by more rapid relaxation than in unstimulated controls. Mid-column rings when freshly prepared show a latency of the order of 120 sec. As the preparation ages, a double response to stimulation appears ; the first response has a latency of about 30-40 sec. and presently becomes the only type of response shown. If two sets of stimuli are applied to a mid-column ring, the magnitude of response to the second set increases as the time between stimulations increases. With long intervals an almost total contraction is obtained in response to a single shock. The effect of intercalated stimuli upon the rhythm of spontaneous activity is studied. The effect is very variable and it is suggested that this is the result of electrical stimulation having both an excitatory and an inhibitory effect. The very long latent periods characteristic of pedal rings and the rhythmic activity of these preparations are interpreted as interactions of excitation and inhibition.
Transmission Through the Last Abdominal Ganglion of the Dragonfly Nymph, Anax Imperator
Authors: Fielden Ann
Published: April 2021

In the last abdominal ganglion of the dragonfly nymph afferent fibres from tactile endings on the paraprocts synapse with large ascending fibres in the ventral nerve cord. The latter run the length of the cord and synapse with efferent fibres in the segmental nerves of the thoracic and abdominal ganglia. The evasion response is mediated by this pathway and can be elicited by electrical stimulation of the nerves from the paraprocts. The synapses between tactile afferents and ascending fibres show delays of 2.0-4.5 msec, and transmit synchronously to frequencies of 50-60/sec. There is no evidence for facilitation at these synapses, but facilitation and/or temporal summation is of importance at the efferent synapses which appear more labile in their properties. Stimulation of the paraproct nerves shows the existence of a reflex connexion between afferents and efferents of the same nerve comparable to that of the vertebrate spinal cord. This provides a preparation for a study of the relationship between sensory and motor neurons in the insect nervous system. Transmission through the last abdominal ganglion and cord is compared with that in the cockroach and locust.
The Landing Responses of Insects
Authors: Goodman Lesley J.
Published: April 2021

Although insect flight, and the stimuli which induce it, have been studied extensively, the way in which insects land has received little attention. The majority of insects fly with the pro- and meso- and in some cases the metathoracic legs folded up beneath the body and the legs must be lowered before the insect makes contact with the landing surface. This paper describes a detailed examination of the movements of the legs of the fly Lucilia sericata and other insects and an attempt to determine the stimuli which result in Lucilia lowering its legs on approaching a suitable landing surface. There are several possible stimuli which may cause the legs to be lowered ; the object which the fly is approaching will appear to increase in size and this stimulus will of necessity be accompanied by a change in the light intensity falling on certain of the ommatidia. If the insect has a reasonable field of binocular vision, the lowering of the legs may be based upon an appreciation of its distance from the landing surface, together with its rate of approach to that surface. Alternatively, it may always lower the legs when the image of the approaching object falls simultaneously on corresponding ommatidia of the two eyes.
A Rubber-Like Protein in Insect Cuticle
Authors: Weis-Fogh Torkel
Published: April 2021

The cuticle of arthropods is complex and varies enormously in structure, properties and composition even within the same species (cf. Richards, 1951). However, the mechanical behaviour is dominated by materials in the solid state of matter so that the mature cuticles hitherto described in the literature may be classed as solid cuticle. It was therefore surprising to find that certain patches of the exoskeleton in many insects exhibit long-range reversible elasticity of the rubber-like type. This paper describes three examples of rubber-like cuticle from locusts (Orthoptera) and dragonflies (Odonata). Similar structures have been found in all winged insects hitherto examined (Weis-Fogh, unpublished). Essentially the present survey is a qualitative analysis of the material basis for the rubber-like properties of three selected samples, based upon simple tests and techniques. The main conclusion is that the characteristic elasticity is caused by a peculiar protein, called resilin, which differs from other structural proteins also in respect of amino-acid composition (Bailey & Weis-Fogh, 1961). Resilin is insoluble in all solvents which do not break peptide bonds and since it is located as an integral part of the highly organized cuticle it is necessary to analyse the three samples in detail as to structure and many other properties. Only in this way is it permissible to conclude that the elasticity depends on only one type of substance and to characterize it in general terms.
Weight Discrimination by Octopus
Authors: Wells M. J.
Published: April 2021

Blinded octopuses can readily be trained to discriminate by touch between objects differing in texture. They seem unable to discriminate between similar objects differing only in weight. The relevance of this to what is already known about the use of proprioceptive information in learning by Octopus is discussed.
The Orientation of Littorina Species to Polarized Light
Authors: Charles G. H.
Published: April 2021

Four British species of Littorina, viz. L. littoralis (L.), L. saxatilis (L.), L. littorea (L.) and L. neritoides (L.), responded when crawling on horizontal surfaces in air and in sea water to plane polarized light incident from above. Photonegative winkles crawled parallel to the plane of vibration (e vector) and photopositive molluscs at right angles to the plane of vibration. The investigations with L. neritoides confirmed the observations of Fraenkel (1927) on the reversal of phototaxis from photonegative to photopositive when this winkle was crawling in the inverted position immersed in sea water. This change of response was considerably influenced by the sea-water temperature, the optimum temperature being withip the range from 10°to 12° C. Examination of the eye failed to reveal biréfringent structures. It is suggested that the mechanism of analysing plane polarized light is a simple reflexion/refraction phenomena based on Fresnel’s laws of refraction of polarized light, the minimum amount of light being refracted into the eye when the animal is crawling parallel to the plane of vibration.
Rates of Establishment of Representations in the Memory of Octopuses With and Without Vertical Lobes
Authors: Young J. Z.
Published: April 2021

The rate of learning to attack a rectangle seen at a distance was studied under various conditions. Learning is rapid only if the food reward is given after the figure has been shown, and if it is near to it. There was no learning to attack if the food was given in the home before showing the figure, nor if the food was given after the octopus had returned to its home. There was no marked difference in rate of learning with trials at intervals of 5 and 50 min. After removal of the vertical lobes learning to attack a rectangle occurred only slowly. Operated animals attacked less reliably after twenty-five trials than normal animals after five trials. After being shocked three times following showings of a rectangle normal animals that had previously learned to attack made few further attacks during the next 4 days. Animals without vertical lobes began to attack again during the same day; little sign of the effects of shocks was seen after 24 hr. The process of forming representations that prevent attack is estimated to be at least five times less efficient in animals without vertical lobes. This was confirmed by the effect of shocks in preventing attacks at crabs. In normal octopuses attacks ceased after two or three shocks at 10 min. intervals and were only resumed 3 days later. Animals without vertical lobes attacked up to ten times in spite of shocks. A few hours later all attacked again. However, some evidence of more enduring representations in the memories was seen. There was no great difference in the effect of shocks given at intervals of 5 and 50 min. in preventing subsequent attacks at crabs by animals without vertical lobes. Under some conditions the more widely spaced shocks produced the greater effect.
The Oxygen Capacity of Goldfish (Carassius Auratus L.) Blood in Relation to Thermal Environment*
Authors: Anthony E. H.
Published: April 2021

The Roughton & Root (1945) modification of the Van Slyke method for measuring haemoglobin content of blood as carboxyhaemoglobin is satisfactory for fish blood, provided at least 0·1 ml. is available. Measurements of iron content are of doubtful value in estimating the oxygen capacity of fish blood. The following photometric methods of determining haemoglobin content were found to be unreliable with fish blood : acid haematin, alkaline haematin and cyanhaematin. The following photometric procedures gave satisfactory measurements of the haemoglobin content of fish blood: Haldane (carboxyhaemoglobin), oxyhaemoglobin and pyridine haemochromogen. Blood from goldfish acclimatized to temperatures near the extremes of their thermal range shows no difference from normal blood in oxygen capacity.
Studies On the Respiration of Sea-Urchin Spermatozoa
Authors: Mohri H. , Horiuchi K.
Published: April 2021

The respiratory quotient of sea-urchin spermatozoa has been determined with Pseudocentrotus depressus, Anthocidaris crassispina and Hemicentrotus pulcherrimus. The R.Q. of sea-urchin spermatozoa, measured by the Warburg direct method, has been reported to be near unity. This was also the case with the present material when the suspending medium was sea water, the R.Q. being 0·8–1·0. It was found, however, that the pH of sperm suspensions was markedly different in the presence and absence of alkali to absorb CO2. When the pH of the suspension was fixed by such buffers as 0·025 M-glycyl glycine, the R.Q. measured by the above method was about 0·7. This is in accord with the results of earlier metabolic studies, which indicated that endogenous phospholipids are the main substrates for the respiration of sea-urchin spermatozoa. The O2 uptake of the present material, however, was found to be little affected by variation in pH. The difference in the R.Q. values obtained with ordinary sea water and buffered sea water, therefore, cannot be explained in terms of pH. When the spermatozoa were suspended in ordinary sea water, the utilization of endogenous phospholipids was much reduced in the absence of alkali, while in buffered sea water the change in phospholipids was almost the same, with and without the absorption of CO2. Determination of the R.Q. by the first method of Dickens & Šimer, in which the O2 uptake and the CO2 output were measured with one and the same sperm suspension, gave a value of about 0·7 with both ordinary and buffered sea water.
A Study in Insect Multiparasitism
Authors: Fisher R. C.
Published: April 2021

The oviposition behaviour of the ichneumon flies·Horogenes chrysostictos and Nemeritis canescens has been examined in relation to their multiparasitism of larvae of the moth Ephestia sericarium. Horogenes is able to distinguish healthy hosts from those that are parasitized by Nemeritis, both when given a simultaneous choice between them and when exposed to each alternately. Although Horogenes attacks fewer parasitized than healthy hosts, it does not lay proportionately fewer eggs in a parasitized host. Nemeritis is also able to distinguish healthy hosts from those parasitized by Horogenes. Though it attacks parasitized hosts more readily than does Horogenes, it lays fewer of its eggs in them. Both species avoid ovipositing in a host containing an advanced larval parasite more frequently than in a host containing a parasite egg. An Ephestia larva multiparasitized by Horogenes and Nemeritis may therefore contain these parasites at widely different ages, but the host selection behaviour of the adult parasites makes multiparasitism by parasite larvae of similar age more likely in field populations.
The Influence of Water-Loading and Low Temperature On Certain Functional Aspects of the Crayfish Antennal Gland*
Authors: Riegel J. A.
Published: April 2021

The influence of water-loading and low-temperature stress on the physiology of the antennal gland was studied in specimens of the freshwater crayfish, Orconectes virilis. The results of experiments on water-loading suggested that the crayfishes were able to excrete water injected into them, but they did so at the expense of an abnormal loss of salts (sodium). Heavy water-loads caused large and prolonged increases in inulin clearances and urine flow. Low temperature had its primary effect in reducing urine flow and inulin clearance. Low temperature apparently had little effect on the rate of sodium excretion or intensity of water excretion. The urine flow (at 16 ° C.) of specimens of O. virilis was determined to be 3 % of the body weight per 24 hr. This value agreed with the urine flow calculated from average inulin clearances and inulin U/B ratios obtained independently upon specimens of the same species. The results presented in the present paper throw further light upon the function of the crayfish antennal gland. They agree fairly closely with results obtained in other animals where filtration is known to play a role in primary urine formation. However, because of limitations imposed, principally by the lack of morphological evidence for a filtration site in the crayfish kidney, it cannot be stated unequivocally that the crayfish antennal gland is a filtration kidney.
Some Observations On the Swimming Behaviour of the Anemone Stomphia Coccinea
Authors: Robson Elaine A.
Published: April 2021

The swimming behaviour of the anemone Stomphia coccinea, previously known to be a specific response to contact with two species of starfish, is briefly described. The sphincter, isolated or intact, gives a reflex quick contraction when the tentacles are stimulated with whole Dermasterias imbricata or with extract, but not when other starfish are used. Sphincter preparations stimulated electrically give a quick facilitated contraction at frequencies above 1 in 3 sec., and slow contractions at fre quencies below 1 in 2 sec. Quick and slow contractions appear to have the same threshold, which is unaffected by the presence of starfish extract. Possible attributes of the chemosensory system are discussed. Elongation of the column is an essential preliminary to swimming, whereas detachment from the substratum, due mainly to contraction of the parieto-basilar muscles, does not always occur. Cutting experiments, and orientated recording of the swimming movements which ensue, suggest that excitation is maintained locally in the column, and that the parieto-basilar and circular muscles function synergically. Multipolar nerve cells in the column may be concerned with this activity. Various special features of the anatomy of Stomphia may be correlated with its ability to swim. Although the origin and adaptive value of the swimming response are still obscure, it is clear that it must be of distinct biological advantage to the species.
The Hydrodynamical Performance of Migratory Salmon
Authors: Osborne M. F. M.
Published: April 2021

The annual spawning migration of Pacific Coast salmon up the Columbia and Amur rivers has been analysed as an experiment on the maximum range of an un-refuelled vehicle, since the fish do not eat during this migration. The fuel (primarily fat) available to real fish is compared to that computed for an equivalent rigid vehicle with the following performance specifications which may be regarded as optimum ones for marine vehicles.

A choice for the speed of ascent against the average river current corresponding to the least fuel consumption, without seeking systematically either low-or high-velocity water. A drag coefficient corresponding to a turbulent boundary layer with no separation. An overall efficiency of 24 % for converting the heat of combustion of the fuel to directed kinetic energy in the wake. Under these assumptions, the vehicles usually require slightly more fuel than the corresponding fish which they are intended to approximate ; in the case of blueback salmon, the vehicle requires about five times as much. One, therefore, concludes that the fish have a performance superior to that of the best engineered rigid vehicles, as defined and operated under the above three specifications. Suggested explanations for the apparently superior performance of the fish are: a deliberate seeking, by the fish, of low-velocity water close to the bottom or shoreline ; the ability of the fish to maintain a laminar rather than turbulent boundary layer; the ability of the fish to extract energy from the turbulent velocity fluctuations of the river.

Analysis of salmon counts over the Bonneville and Rock Island dams on the Columbia River shows that the average velocity of the fish upstream is influenced by the velocity of the water downstream in the following peculiar fashion, depending upon whether one considers water-velocity variations through the course of a year, or variations at a fixed season of the year, from one year to the next. The general effect of the water velocity as it varies through a year, is to slow the fish down when the water velocity is large (at the June flood peak) and to permit faster ascent when the water velocity is less, in both preceding and following months. But at a fixed season of the year, prior to the flood peak in June, relatively high-velocity water speeds the fish up. At a fixed season after the flood peak, relatively high-velocity water slows them down. These relationships are in agreement with other biological observations and with an analysis of navigation for minimum fuel consumption.

Data and methods are given permitting a calculation of the average water velocity in the Columbia River, from the mouth to the headwaters, for any season of the year.
Studies On Salt and Water Balance in Caddis Larvae (Trichoptera)
Authors: Sutcliffe D. W.
Published: April 2021

Survival and regulation in sea-water media was studied in the freshwater caddises Limnephilus stigma and Anabolia nervosa. The majority of larvae did not survive for more than a few days at external salt concentrations greater than about 60 mM./l. NaCI. In sea-water media the haemolymph osmotic pressure increased to remain slightly hyper-osmotic to the medium. The haemolymph sodium level also increased to remain slightly hypertonic to the medium, but the chloride level was maintained hypotonic until just prior to death of the larvae. When the haemolymph chloride concentration was raised above the normal level, the Malpighian tubule-rectal system elaborated fluid in which the chloride concentration was hypertonic to the haemolymph. The system is highly sensitive to changes in the haemolymph chloride level. The regulation of body-fluid composition in the freshwater caddises is compared with that found previously in the euryhaline larvae of Limnephilus affinis. It is suggested that the maintenance of a low haemolymph sodium concentration L. affinis larvae is an important part of the adaptation for survival in salt water.
The Response of the Dogfish to Anoxia
Authors: Satchell G. H.
Published: April 2021

It has been suggested repeatedly that the mammalian response to anoxia of hyperpnoea and hypertension may be the survival in air-breathing vertebrates of a phylogenetically primitive mechanism present in fish (Marshall & Rosenfeld, 1936; Schmidt & Comroe, 1940; Schmidt, 1956; Heymans & Neil, 1958). Black (1951), reviewing the results of four previous studies on the effect of deoxygenated sea water on elasmobranch fish, concluded that there was no change in respiration, whilst Lutz (1930) showed that restriction of water flow through the dogfish pharynx (a change likely to cause anoxia) resulted in a slowing both of respiration and heart beat. Thus the evidence, fragmentary though it is, does not suggest that the response of an elasmobranch fish to anoxia is like that of a mammal. In an attempt to re-examine this problem using the common local dogfish Squalus acanthias* L., the work of Lutz has been confirmed and amplified. Reduction of the minute volume of pharyngeal flow caused bradycardia and respiratory slowing. It soon became clear, however, that the responses of the heart and of respiration were mediated by separate mechanisms. Respiratory rate was related primarily to minute volume and was much less influenced by the oxygen content of the water respired. The heart, by contrast, was reflexly slowed by anoxia, whether this was induced by a restricted flow of normally oxygenated water or an ample flow of deoxygenated water.
A Study in Insect Multiparasitism
Authors: Fisher Roderick C.
Published: April 2021

In multiparasitism of larvae of the moth Ephestia serecarium by the solitary ichneumonid endoparasitoids Horogenes chrysostictos and Nemeritis canescens, neither has an intrinsic superiority over the other and free competition occurs between their immature stages for possession of the host. There is no interaction between the eggs of these species before they hatch. When larvae of these two species are present in the same host at the same time they compete for possession of the host by one of two mechanisms, physical attack or physiological suppression. When the larvae hatch from the eggs at the same time, neither has a clear advantage over the other and either species may win by physically attacking the other with its mandibles. If they are of different ages, the older larva usually wins by physical attack when the difference in age is less than 40 hr. at 25° C. If the difference in age is 50 hr. or more at 25° C. the older larva always wins in competition by physiological suppression of the younger one. The factors which are important in determining the result of competition are: difference in age between the 1st-instar larvae at eclosion, environmental temperature and the species of host attacked, which determine the parasites’ rate of development. A hypothesis of asphyxiation is presented with experimental evidence of its validity as an explanation of the physiological suppression of supernumerary parasitoids. It is suggested that asphyxiation by oxygen-lack can better account for physiological suppression than the theories of toxic secretion, specific inhibitor and starvation.
The Relationships Between Nutrition, Hormones and Reproduction in the Blowfly Calliphora Erythrocephala (Meig.)
Authors: Strangways-Dixon J.
Published: April 2021

A study has been made of the effects of removal of ovaries, copora allata (c.a.) and median neurosecretory cells (m.n.c.) upon the selection by female blowflies of carbohydrate (sugar in water) or ‘protein’ (Mannite in milk). Extirpation of the ovaries resulted in high carbohydrate-low protein selection and in hypertrophy of the c.a. Extirpation of the c.a. resulted in low carbohydrate selection. Extirpation of both ovaries and c.a. resulted in low carbohydrate selection. These and other results suggest that selection is independent of direct ovarian control, but that the ovaries influence selection in that they utilize the ingested foods and thus bring about the succession of feeding cycles. The c.a., whose volume (activity?) changes cyclically during each cycle of reproduction, appears to control the fluctuations in carbohydrate consumption. The m.n.c. seem to be necessary for the ingestion of ‘protein’ and for the activity of the c.a. Reproductive cycles tend to overlap. The succeeding cycle in a gravid female must be taken into consideration when events are being related to reproduction.
The Physiology of Blood Trehalose and its Function During Flight in the Blowfly
Authors: Clegg James S. , Evans David R.
Published: April 2021

The finding (Evans & Dethier, 1957) that glucose and trehalose are the normal blood sugars of the blowfly Phormia regina has been confirmed. It is estimated that most of the flight energy is derived from the oxidation of trehalose and, to a lesser extent, of other sugars found in the blood. Several lines of evidence indicate that the concentration of blood trehalose normally regulates the rate at which energy is expended by the flight muscles during flight. ‘Exhaustion’ results when trehalose cannot be supplied to the flight muscle at the necessary rate. Fat body is the chief source of blood trehalose; endogenous and exogenous substrates are used for its synthesis. The rate of blood trehalose synthesis can be very rapid, almost compensating for the rate of utilization by the flight muscle during flight. It appears, therefore, that the intensity of flight is determined largely by the interaction of two rate processes : the rate of trehalose utilization (flight muscles) and the rate of trehalose synthesis (fat body). A diagram is presented which accounts for the establishment of glucose and trehalose as the normal blood sugars of this fly and summarizes our findings on the transfer of carbohydrates between various tissues. The blood volume (6–7 μl.) has been estimated from dilution of injected 14C-inulin. This volume is not changed appreciably by flight
Nutritional Requirements of Axenically CulturedDrosophila MelanogasterAdults
Authors: Sang James H. , King Robert C.
Published: April 2021

A technique is described for the culture of germ-free Drosophila adults on defined diets. The complete larval diet, with the agar base replaced by cotton-wool, was found to be adequate for adults and permitted them to lay more or less normal numbers of eggs during a 16-day test period. Omission tests showed that casein, the B vitamins (other than B12 and biotin) K and Mg were essential for normal ovary development. Casein could be replaced with an amino acid mixture. The ten ‘essential’ amino acids were all found necessary for egg production but arginine, histidine and methiohine were apparently synthesized, although at an inadequate rate. The remaining essential amino acids seemed to be the nutrients required in the greatest amounts since egg production stopped soonest when they were omitted. Individual ‘nonessential’ amino acids could be removed from the mixture, but a supply of them was necessary for normal egg production and viability. Omission of fructose lowers egg production but does not cause its cessation even after 16 days. The difficulty of determining that essential supplies are not being met by contaminants is illustrated by examination of cholesterol requirements. In this case, and possibly also for choline, the requirement for egg formation is very much less than for larval development, and might be satisfied from contamination of the medium constituents. Neglecting these trace supplies (which can be measured only in fractions of a microgram per 5 ml. medium) RNA, choline, cholesterol and biotin seem unnecessary for egg formation. The quantitative requirements of the normal adult female must therefore be different from those of the larva. It was not possible to produce a true P deficiency, or to be certain that traces of Ca and Cl in the medium were not sufficient to permit normal fecundity. The ovary is shown to be capable of recovery from protein starvation and to respond to omission of single essential amino acids by ceasing to form new chambers. The majority of deficiencies result in inhibition of vitellogenesis, after a period when inviable eggs are laid. Only Mg and pyridoxine omission produced distinguishable pathological changes, which are illustrated.
Centres for Tactile and Visual Learning in the Brain of Octopus
Authors: Wells M. J.
Published: April 2021

Octopuses were trained to stop reacting to visual and tactile stimuli normally eliciting positive responses, and to make visual and tactile discriminations. The effect on performance of removal of parts from the brain was observed. It appears that Octopus has two learning systems, one in the inferior frontal and subfrontal lobes, dealing with tactile discrimination on a basis of the proportion of sense organs excited, the other in the optic lobes, handling visual discrimination on a basis of the pattern of sense organs excited. The vertical lobe plays a part in learning by either system, and is to some extent a store for both tactile and visual memories.
Studies on Salt and Water Balance in Caddis Larvae (Trichoptera)
Authors: Sutcliffe D. W.
Published: April 2021

Two freshwater caddis larvae, L. stigma and A. nervosa, drink and regurgitate large quantities of salt water at frequent intervals. Drinking is not controlled, and larvae may drink an amount equivalent to 50 % of the body weight per day. The gut wall is adversely affected by salt water and exosmosis occurs across the gut wall. L. affinis larvae drink only small quantities of salt water. Drinking is strictly controlled, and the intake is roughly equivalent to 3–7 % of the body weight per day over a wide range of external salt concentrations. The gut wall is not affected by high salt concentrations ; regurgitation and exosmosis do not normally occur. In the freshwater caddises the rate of rectal fluid production is approximately equivalent to 7 % of the body weight per day. Rectal fluid is not produced at high external salt concentrations. L. affinis larvae continue to produce rectal fluid at very high external salt concentrations. The daily output is probably roughly equivalent to the daily intake of salt water by drinking. The osmoregulatory mechanism in L. affinis larvae and other salt-water insects is discussed. It is suggested that controlled drinking forms an important part of this mechanism, together with the ability of the gut wall to withstand exposure to high salt concentrations and the ability to elaborate rectal fluid hyper-osmotic to the external medium.
Kidney Function in the Crab-Eating Frog (Rana Cancrivora)
Authors: Schmidt-Nielsen Knut , Lee Ping
Published: April 2021

A study has been made of kidney function in the crab-eating frog, Rana cancrivora, of south-east Asia. This frog can live in full-strength sea water; in such concentrated media its blood is slightly hypertonic to the medium, and a considerable part of the osmotic concentration is due to urea. In concentrated media the excretion of urea is greatly diminished. This is not due to active tubular reabsorption of urea, but primarily to a low urine flow caused by increased tubular reabsorption of water and reduced glomerular filtration. In concentrated media, as compared with dilute media, only a few percent of the filtered urea appears in the urine. Osmoregulation of the crab-eating frog in sea water resembles that of elasmobranchs except in that there is no evidence of active tubular reabsorption of urea in the frog.
Desquamation in Actinophrys: Induction and Inhibition
Authors: Kitching J. A.
Published: April 2021

The ‘skin’ raised by Actinophrys sol in response to bovine plasma albumin is thicker and more coherent in higher concentrations of the protein, and imprisons the Actinophrys for longer. Escape from thick skins is effected by the swelling of vacuoles, after the manner used by various Protozoa in excystment. Some limited power of further desquamation is recovered after an interval of one day. Desquamation can occur at all pH values from 5·4 to 9·0. However, skins are not formed in the more alkaline solutions at low concentrations of plasma albumin. Gelatin and ribonuclease are active in provoking desquamation. Egg albumin is less effective. Various amino acids proved entirely ineffective. Various inorganic salts failed to cause desquamation. Desquamation in response to bovine plasma albumin was visibly inhibited by the presence of MgSO4, MgCl, and (to some extent) by salts of Sr and Ca. A competition between Mg and the protein for active sites is suggested. A mixture of MgSO4 and serum albumin provoke a temporary spreading and lobulation of the bases of the axopods. In solutions of MgSO4 or bovine plasma albumin, separate individuals of Actinophrys tend to fuse together in ‘plasmogamy’. The various observations are tentatively interpreted primarily in terms of a surface reaction, although it is likely that the mechanisms of response are complicated.
The Imaginal Ecdysis of Blowflies. Detection of the Blood-Borne Darkening Factor and Determination of Some of Its Properties
Authors: Cottrell C. B.
Published: April 2021

At the imaginal ecdysis of Calliphora erythrocephala (Meigen) the initiation of normal hardening and darkening is brought about by the release into the blood of an active factor (Cottrell, 1962b). The darkening factor can be detected in fly blood by injecting it into flies decapitated at the moment of emergence. Blood taken from flies at the moment of emergence or 24 hr. after expansion produces little or no reaction, although blood taken between 3 min. and 10 hr. after emergence shows darkening activity. However, extracts of other tissues and many chemicals will also induce darkening though probably unspecifically through damage effects. The assay can therefore be used certainly only for detecting activity in fly blood. The blood-borne darkening factor of blowflies will withstand boiling for 10 min. or drying at 120° C. for 20 min., but it does not retain its activity when kept in solution at room temperature for more than 24 hr. It is non-dialysable, relatively insoluble in organic solvents and is inactivated by ethyl alcohol and the bacterial protease subtilisin. It is probably proteinaceous and is certainly not tyrosine or any of the phenolic compounds at present thought to act as the precursors of the tanning agent. The blood-borne factor of different blowflies (Calliphora, Sarcophaga and Lucilia) is not species-specific and there is some inconclusive evidence that a similar factor is present at the ecdysis of Schistocerca.
Spiracle Control in Adult Dragonflies (Odonata)
Authors: Miller P. L.
Published: April 2021

Spiracle activity is described in four species of adult dragonfly (Anisoptera) at rest, in flight and during recovery from flight. The closer muscle of spiracle 2 reacts directly to locally applied carbon dioxide. In one species this results in maintained opening of the valve, and in the other three in movements synchronized with abdominal ventilation. Neither reaction involves a change in the patterns of nerve impulses in the motor nerve to the closer muscle. Conditions of partial anoxia have no direct action on the spiracle but they reduce the frequency of impulses in the motor nerve, thereby increasing the sensitivity of the closer muscle to carbon dioxide. A central inhibitory reflex accounts for spiracle opening at the start of flight. Various stimuli are described which excite this reflex. Rhythmically-firing ventilation centres are confined to the abdomen, but the brain and thoracic ganglia exert a considerable influence over ventilation. In species whose thoracic spiracles are at times synchronized with ventilation, volleys of impulses ascend the cord and regularly superimpose a burst at high frequency (and in one species a subsequent brief inhibition) on the otherwise constant firing of the spiracle motor neurones. In the presence of carbon dioxide these bring about synchronized movements. Synchronized spiracle movements probably give rise to a one-way airstream in tracheae which pass axially up through the flight muscles and then posteriorly along the abdomen. In some species the stream may pass in the reverse direction. Among thirty-five species of dragonfly examined in Uganda synchronized movements of the thoracic spiracles are found in all species active during the day; in five species which are active only during crepuscular periods they are absent. The possibility is discussed that these movements are important for cooling as well as for respiration.
The Effect of Light On the Shadow Reaction of the Sea Urchin, Diadema Setosum (Leske)
Authors: Yoshida M.
Published: April 2021

As is mentioned by Mortensen (1940), sea urchins which belong to the genus Diadema react to shadow by spine movements. Since the work of Millott (1954) these responses have been extensively studied on an Atlantic species, D. antillarum. In preliminary experiments on a Japanese species, D. setosum, some of the important findings in the Atlantic species, such as the part played by radial nerves in the reflex (Millott, 1954), the photosensitivity of the nervous elements (Yoshida & Millott, 1959) and the inhibitory effect of light on the reaction (Millott & Yoshida, 1960 a, b), were confirmed. This made it possible to base the work on the Japanese species on what has been found in D. antillarum.