bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Mechanism of Osmotic Regulation in Artemia Salina (L.): The Physiology of the Branchiae
Authors: Croghan P. C. 
Published: April 2021

ABSTRACT
The uptake of silver ions by Artemia has been investigated. The staining is localized to the first ten pairs of branchiae. There is no staining of the eleventh pair or of any other part of the animal. The uptake of silver is due to a purely passive precipitation of AgCl within the thickness of the branchial cuticle. The effects of KMnO4 and methylene-blue solutions have also been studied. Their effect is localized to the epithelium under the cuticle of the first ten pairs of branchiae. It is concluded that all these staining reactions demonstrate that the cuticle over the first ten pairs of branchiae is the only part of the external cuticle that is appreciably permeable. Animals whose branchial epithelium has been damaged by a brief exposure to saturated KMnO4 solution have lost the ability to osmo-regulate. They are closely isotonic with their medium, and the range of external concentration tolerated is much restricted. This isotonicity is not due simply to increased permeability, but is due to specific destruction of the mechanism normally excreting NaCl in hypertonic media. Correlation of the physiological effects of KMnO4 treatment with the sharp localization of damage, and the evidence for localized permeability indicates that the epithelium of the first ten pairs of branchiae is the site of active NaCl excretion in hypertonic media, and probably of active uptake from hypotonic media. The ontogeny of this mechanism is traced. In nauplii the dorsal organ is apparently concerned in NaCl excretion. When the branchiae develop the dorsal organ degenerates.
The Mechanism of Osmotic Regulation in Artemia Salina (L.): The Physiology of the Gut
Authors: Croghan P. C. 
Published: April 2021

ABSTRACT
Artemia is continuously swallowing its medium, whether it is hyper-, iso-, or hypotonic to the haemolymph, and taking up water from the gut lumen. The osmotic pressure of the gut fluids is appreciably greater than that of the haemolymph, but in the more concentrated media is considerably below that of the medium. This indicates that considerable amounts of NaCl must be passing across the gut epithelium into the haemolymph. The concentration of both sodium and chloride ions in the gut fluids is always less than that in the haemolymph, indicating that there must be an active uptake of NaCl across the gut epithelium. 4. It is considered that the gut of Artemia has become adapted as a mechanism for the active uptake of water, controlling water balance and preventing dehydration in hypertonic media. 5. The adaptations for maintaining the NaCl and the water balances in Artemia are compared to those found in the marine teleosts, and are shown to be extremely similar.
Studies On the Feeding and Nutrition ofTuberolachnus Salignus(Gmelin) (Homoptera, Aphididae)
Authors: Mittler T. E. 
Published: April 2021

ABSTRACTSeveral workers have tried to ascertain the nitrogenous and carbohydrate materials which are ingested by aphids and coccids by analysing juices, phloem exudates and extracts obtained from the insects’ host plants (Evans, 1938; Michel, 1942; Lindemann, 1948; Auclair & Maltais, 1950, 1952; Gray, 1952; Hackman & Trikojus, 1952; Gray & Fraenkel, 1954; Bacon & Dickinson, 1957). It remains to be established, however, whether the insects ingest materials in the same form and at the same concentration as they occur in their host plants. The present paper gives details of a method, outlined by Kennedy & Mittler (1953), for obtaining the sap which normally enters the alimentary canal of feeding Tuberolachnus salignus (Gmelin). By determining the nitrogen and sugar composition of this sap and that of the honeydew excreted by the aphid, it was possible to examine the chemical relationship existing between the insect’s food and its excreta.
The Effect of Weak Electrolyte Solutions on the Hatching Rate of the Eggs of Trichostrongylus Retortaeformis (Zeder) and Its Interpretation in Terms of A Proposed Hatching Mechanism of Strongyloid Eggs
Authors: Wilson P. A. G. 
Published: April 2021

ABSTRACT
The influence of solutions of NaCl on the hatching of eggs of Trichostrongylus retortaeformis is studied. It is shown that the effects are not the consequence of colligative properties, but are related to ionic phenomena. 0·05 N-NaCl slows down the rate of hatch without impairing the ultimate ‘hatchability’of the eggs. Processes of development up to hatching are not slowed down. The effect demonstrated in the case of NaCl is shown to be shared by eight other electrolytes, the depression in the rate of hatch being proportional to the mobility of the ions in solution. On the assumption that the effect of the ions is due to a penetration of the egg membrane(s) the rate of entry is shown to be controlled by the speed of the slower ion in any one salt. The influence of NaCl on the permeability of hatching eggs to water is studied. It is shown that the rate of increase in permeability is slowed down sufficiently in NaCl to control the rate of hatch. The inference that water permeability is a necessary prerequisite for hatching is made, a further hypothetical process being invoked to account for the rate of hatch in the absence of NaCl, since it is not then controlled by changes in water permeability. The probability that the net effect of ionic solutions on the eggs is one concerned with the rate of breakdown of the inner wax-like layer of the egg is strengthened by experiments demonstrating that the depressing influence of NaCl is antagonized by ‘Teepol’, though the comparable influence of other, non-emulsifying, compounds cannot be explained. The role of water permeability in the hatching mechanism is investigated. A hatching mechanism of strongyloid eggs is proposed which involves two processes, the first dependent upon the osmotic relationships of the unhatched larva to its environment, the second being some sort of chemical weakening of the outer shell. It is suggested that the effect of ions on hatching rate assists the ‘embryonated egg’ to survive under natural conditions when the hatched first-stage larva might otherwise be destroyed by desiccation.
Tidal and Diurnal Rhythms of Locomotory Activity in Carcinus Maenas (L.)
Authors: Naylor E. 
Published: April 2021

ABSTRACT
Spontaneous locomotory activity was recorded continuously for several days in Carcinus maenas (L.). A complex rhythm was observed which could be analysed into two components, one of diurnal frequency (24 hr.), with peaks of activity during the hours of darkness, and one of tidal frequency (ca. 12·4 hr.), with peaks at the time of high tide. The rhythms persist in constant dim light at constant temperatures, whether the crabs are kept moist in air or continuously immersed in sea water. The resultant effect of the two rhythms is to produce particularly high activity peaks during periods which recur with a semi-lunar frequency. Experimental results relate to observed behaviour on the shore.
The Absorption and Metabolism of Some Sugars in the Locust, Schistocerca Gregaria (Forsk.)
Authors: Treherne J. E. 
Published: April 2021

ABSTRACT
The uptake of 14C-labelled glucose, mannose and fructose from the alimentary canal of Schistocerca gregaria (Forsk.) has been studied using the dye Amaranth as a reference substance. Absorption was confined to the mid-gut, the proportion absorbed by the caeca depending on the type of sugar and its concentration in the gut lumen. The absorbed sugars were converted, in varying degrees, to trehalose which accumulated in the haemolymph. The extent of the conversion appeared to parallel the rate of absorption of the sugars at the various concentrations. The sugars passed through the gut wall at similar rates in experiments in which the isolated alimentary canal was suspended in a large volume of circulating poisoned saline. The passage through the gut wall under these conditions was equivalent to the rapid absorption obtained in vivo when there was a rapid conversion to trehalose. It is suggested that these observations support the hypothesis that the sugars are absorbed by diffusion across the gut wall and that the process is facilitated by the rapid conversion to trehalose in the haemolymph, which tends to maintain a steep concentration gradient. At very low concentrations in the gut lumen, glucose was at a similar level to the relatively small amount of glucose in equilibrium with the trehalose in the haemolymph. When the specific activity of injected 14C in the haemolymph approximated to that in the gut lumen the absorption of the labelled glucose from the mid-gut caeca was reduced at very low concentrations. Thus at these levels it is suggested that most of the absorption of labelled glucose can be attributed to an exchange with that in the haemolymph. At a concentration of 0·01 M/1. the proportion exchanging became negligibly small and the absorption of the labelled glucose molecules approximated to the net glucose absorption.
Gas Secretion in Fishes Lacking Rete Mirabile
Authors: Sundnes G. , Enns T. , Scholander P. F. 
Published: April 2021

ABSTRACT
In most fishes with a closed swimbladder the gas secretion is confined to a special organ, the so-called red gland, which consists of a secretory epithelium supported by a counter-current capillary system, the rete mirabile. All the fishes investigated which possess this structure are capable of accumulating oxygen, and most of them also nitrogen, in the swimbladder against a pressure gradient. In other fishes the rete mirabile is lacking, and instead the secreting epithelium lines the swimbladder directly. Many fishes in this category apparently secrete only nitrogen.
Induced Ovarian Development in Decapitated Mosquitoes by Transfusion of Haemolymph
Authors: Gillett J. D. 
Published: April 2021

ABSTRACT
Ovarian development in mosquitoes appears to be under hormonal control. Evidence for this view has been derived from experiments involving removal of the endocrine organs assumed to be responsible for production of the hormone by decapitation or ligation of the thorax, before and after a critical period. (Detinova, 1945; Clements, 1956; Gillett, 1956b, 1957). Such evidence, however, even when supported by histological studies, is indirect and does not entirely exclude the possibility of alternative explanations; nor are the grounds for criticism removed when insects are joined in parabiosis (Wigglesworth, 1936, 1954; Williams, 1946). The present paper describes induction of ovarian development in mosquitoes, decapitated before the critical period, by transfusion of haemolymph from normal donors.
Effects of the ant,Lasius NigerL., on the Feeding and Excretion of the Bean Aphid,Aphis FabaeScop
Authors: Banks C. J. , Nixon H. L. 
Published: April 2021

ABSTRACTBanks (1958) confirmed that colonies of Aphis fabae, attended by the ant Lasius niger, multiply more than ant-free colonies on bean plants, in the absence of the aphids’ insect enemies. He showed that, when the aphids were ant-attended, they changed their excretion behaviour and that the normal dispersal of adult apterae from young apical growth of bean plants was delayed. No significant differences were found between the reproduction rates of individual ant-attended and ant-free aphids living on leaves of the same age, but the reproduction rates were significantly affected by the age of the plant tissue on which the aphids fed. The increased multiplication of ant-attended colonies was attributed to the delay in dispersal of adult apterae from the young growth, where they reproduced more, to the old growth, where they reproduced less.
Factors Controlling the Change of Shape of Certain Nemertean and Turbellarian Worms
Authors: Clark R. B. , Cowey J. B. 
Published: April 2021

ABSTRACT
Nemerteans and turbellarians have an inextensible fibre system around them in the form of a lattice of left-and right-handed spirals. The effect of this system on the change of shape on these worms has been analysed theoretically and compared with the observed behaviour of nine species of turbellarian and nemertean from widely differing habitats. The following theoretical relationships have been studied: (a) Variation of the angle between the geodesics and the longitudinal axis of the worm during changes in length, and the role of the fibre system in limiting changes in length of the animal. (b) The change in cross-sectional shape during changes in length. (c) The extension of the fibres and the extensibility of the worms, assuming the fibres of the lattice to be elastic. The species investigated conform with the theoretical predictions to varying degrees and have been grouped accordingly : (a) Geonemertes dendyi and Rhynchodemus biUneatus have low extensibilities and fit the prediction well. They are nearly circular in cross-section at all lengths as a result of their low extensibility and this is related to their terrestrial habit and need for water conservation. (b) Amphiporus lactifloreus, Lineus gesserensis and L. longissimus are moderately flattened in the relaxed position and have extensibilities between 6 and 10. They are marine crawling forms using cilia for locomotion and so must present a fairly large ciliated surface to the substratum. The fibre system does not limit contraction; the compression of the epithelial cells causes the observed extensibilities to fall a little short of the theoretical values. (c) Cerebratulus lacteus, Malacobdella grossa, Polycelis nigra and Dendrocoelum lacteum are very flattened forms and have very high theoretical extensibilities, but very low observed ones. The factors causing this are the thickness of the body-wall musculature (Cerebratulus), the limiting effect of longitudinal and circular reticulin fibres in the muscle layers, and the presence of dorso-ventral and diagonal muscles. Their flattened form is correlated with ecological factors (with swimming in Cerebratulus, with its parasitic life in the mantle of bivalves in Melacobdella) or with physical ones in turbellarians where a permanently flattened form is necessary for these worms to move by ciliary action.
Some Experiments on Form Perception in the Nymphs of the Desert Locust, Schistocerca Gregaria Forskål
Authors: Wallace G. K. 
Published: April 2021

ABSTRACT
Nymphs of the desert locust are spontaneously attracted to simple forms in the visual environment, and show a preference for certain figures. Experiments are described which analyse certain of the important properties which make a figure attractive to this insect. The insects show a preference for long straight vertical edges as opposed to short straight vertical edges. Straight vertical edges are preferred to straight oblique edges and vertical figures with straight edges are preferred to vertical figures with wavy or serrated edges. In the absence of straight vertical edges a preference is shown for the figure with the more complex contour (for figures of comparable size). It is postulated that in this insect form discrimination is based on the number of stimulus changes per unit time produced by moving contours and on the spatial and temporal distribution of such changes. The results are compared with those of previous workers and in particular with those of Hertz and of Wolf and Zerrahn-Wolf on the bee.
The Digestion and absorption of Tripalmitin in the Cockroach, Periplaneta Americana L
Authors: Treherne J. E. 
Published: April 2021

ABSTRACT
A partial hydrolysis of 14C-labelled tripalmitin has been demonstrated in the crop of Periplaneta americana L. No significant absorption of tripalmitin and its derivatives could be demonstrated in the crop, whether the tripalmitin was suspended in an experimental fluid or dissolved in emulsified oleic acid. Absorption took place in the mid-gut and appeared to be largely confined to the caeca and the anterior part of the ventriculus. The total absorption of tripalmitin showed a linear relation with crop emptying, suggesting that the rate at which the material was allowed to leave the crop, rather than the uptake in the mid-gut, was the limiting factor in absorption.
Osmoregulation in the Muscle Fibres of Carcinus Maenas
Authors: Shaw J. 
Published: April 2021

ABSTRACT
Measurements have been made of the freezing-point depression of single muscle fibres of Carcinus maenas and of the concentrations of the non-protein nitrogenous components of the muscle. When the blood is diluted the osmotic activity of the muscle fibres always falls in proportion. The fibres are probably always in osmotic equilibrium with the blood. The osmotic activity of the fibres can be accounted for in terms of the concentrations of the muscle ions together with nitrogen-containing compounds, such as free amino acids, taurine and trimethylamine oxide. These organic substances account for over 60 % of the total osmotic pressure. In crabs from dilute sea water the concentrations of the nitrogenous compounds are reduced below the level expected from the increase in water content of the muscle. It is suggested that the muscle fibre can prevent excessive water intake by the removal of nitrogenous substances, thus reducing the internal osmotic activity. The process is reversible. The importance of the mechanism in relation to the adaptability of the cell to reduced blood concentration is discussed.
Observations on the Temperature Regulation and Food Consumption of Honeybees (Apis Mellifera)
Authors: Free J. B. , Spencer-Booth Yvette 
Published: April 2021

ABSTRACT
Bees have been kept in groups whose numbers ranged from 10 to 200 bees, at temperatures ranging from 0–40° C. At 40° C. bees in groups of 200 had a higher death-rate than bees in smaller groups. At temperatures of 25–350 C. the death-rate was low and about the same in all groups. Below 25° C. the more bees in a group, the longer they survived. The temperatures of all groups increased with that of their environment, the larger a group, the higher its temperature. The difference between the external temperature and that of the groups decreased with increase in the former until at 35 and 40° C. groups of all sizes were at or slightly below environmental temperature. At temperatures from 20–40° C. the percentage of bees in a group that were clustering was directly related to the size of their group, bees in groups of 10 or 25 hardly clustering at all. At each temperature at 15° C. or below, about the same high percentage of bees clustered in all groups. The amount of food (sugar syrup) consumed per bee increased with decrease in the environmental temperature. Very little water was drunk at environmental temperatures of 25° C. or lower but, at 35° C. and above, relatively enormous quantities were taken. These results have been discussed especially in relation to information on the temperature regulation and food consumption of colonies in winter.
Hormonal Control of Sexual Maturity in Octopus
Authors: Wells M. J. , Wells J. 
Published: April 2021

ABSTRACT
Gonad and body weight records have been collected for 487 individual octopuses over a period of 3 years. In the size range used for experiments (200–1000 g.), the ovary is always immature in control animals, and constitutes only about 1/500th of the total body weight. The testis is rather larger, generally ripe, and forms about 1/100th of the body weight, increasing somewhat relative to the size of the body over the range considered. Following optic nerve section, or removal of certain parts of the supraoesophageal lobes, the gonads enlarge. In females the ovary enlarges from 1/500th to as much as 1 /5th of the total body weight within 5 weeks of operation and this may be followed by laying of fertile eggs that are brooded in a normal manner. In males where the testis is generally mature before operation the enlargement produced is only of the order of 50%. Enlargement of testis or ovary is always accompanied by enlargement of one or both of the optic glands, and operational treatments that normally cause enlargement of the gonad are ineffective if the optic glands are first removed. The optic glands are innervated from the subpedunculate/dorsal basal area in the hind part of the supraoesophageal brain mass. Lesions in this area, or severance of the nerve tracts running along the sides of the brain from it to the optic glands, cause these and the gonads to enlarge. Unilateral central lesions or optic nerve section cause optic gland enlargement on the operated side only, but appear to be as effective in determining gonad enlargement as bilateral treatments. It is concluded that maturation of the gonad is determined by secretion from the optic glands which is normally held in check by an inhibitory nerve supply from the subpedunculate/dorsal basal lobe area. The action of this region is in turn dependent upon the integrity of the optic nerves and thus, presumably, upon light. This system in cephalopods is compared with analogous systems regulating sexual maturity in arthropods and vertebrates.
The Absorption of Sodium Ions by the Crayfish, Astacus Pallipes Lereboullet
Authors: Shaw J. 
Published: April 2021

ABSTRACT
The effects of external and internal sodium concentrations.on the uptake of sodium ions by the crayfish, Astacus pallipes, has been studied. The normal sodium influx, measured with 24Na, from 0-3 mM./l. NaCl solution is 1-5 /xM./io g. body weight/hr. The rate of loss of sodium to de-ionized water has roughly the same value. Net loss of sodium reduces the external sodium concentration required for sodium balance. The minimum equilibrium concentration is about 0 04 mM./l. NaCl. The relation between the external sodium concentration and the sodium influx is non-linear. The influx has a maximum of about 10μM./IO g./hr. at an external concentration of approx. 1 mM./l. The 24Na influx is a true measure of the sodium uptake rate at low external concentrations. At higher concentrations the influx may exceed the uptake rate by some 20%. Net loss of sodium increases the influx by three to five times. Loss of 5-10% of the total internal sodium increases the influx from the normal to the maximum level. A 1 % change has a significant effect on the influx. Changes in the internal sodium content reflect changes of the blood sodium concentration. A scheme is suggested whereby the external and internal sodium concentrations interact together on the influx to produce a self-regulating system which maintains the animal in sodium balance.
Salt and Water Balance in the East African Fresh-Water Crab, Potamon Niloticus (M. Edw.)
Authors: Shaw J. 
Published: April 2021

ABSTRACT
The mechanisms of salt and water balance in the East African fresh-water crab, Potamon niloticus, have been investigated. The freezing-point depression of the blood is equivalent to that of a 271 mM./l. NaCl solution. The animals cannot survive in solutions more concentrated than 75% sea water. Above the normal blood concentration, the blood osmotic pressure follows that of the medium. The urine is iso-osmotic with the blood and is produced at a very slow rate. The potassium content is only half that of the blood. The animal loses sodium at a rate of 8 µM./10 g./hr. mainly through the body surface. Potassium loss occurs at one-sixteenth of this rate. Sodium balance can be maintained at a minimum external concentration of 0-05 mM./l. Potassium requires a concentration of 0·07 mM./l. Active absorption of both sodium and potassium occurs. The rate of uptake of sodium depends on the extent of previous sodium loss. The rate of sodium uptake may be affected by such environmental factors as the salt content of the water, temperature and oxygen tension. The normal oxygen consumption rate is 0-72 mg./io g./hr. A minimum of 2-3 % is used in doing osmotic work to maintain salt balance. The salt and water balance in Potamon is discussed in relation to the adaptation of the Crustacea to fresh water. The importance of permeability changes is stressed.