bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Rubber-Like Protein in Insect Cuticle
Authors: Weis-Fogh Torkel 
Published: April 2021

ABSTRACT
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 Similar structures have been found in all winged insects hitherto examined (Weis-Fogh, unpublished).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.
The Orientation of Littorina Species to Polarized Light
Authors: Charles G. H. 
Published: April 2021

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACTIn 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

ABSTRACT
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

ABSTRACT
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

ABSTRACTA 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.