bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Excretory System of the Stick Insect, Dixippus Morosus (Orthoptera, Phasmidae)
Authors: Ramsay J. A. 
Published: April 2021

ABSTRACT
The excretory system (Malpighian tubules and hindgut) of the stick insect is described, in extension of the earlier description by de Sinéty. Analyses have been made of the inorganic components of serum (haemolymph heat-coagulated and centrifuged), of urine (the fluid produced by the Malpighian tubules), of faeces, eggs and privet leaves. In the adult female insect most of the calcium ingested leaves the body with the eggs. The haemolymph has the characteristic mineral base pattern of the herbivorous insect; it appears to be supersaturated with magnesium phosphate. Its volume varies from 70 to 180 mm.3, with an average value of 130 mm.3, representing about 15% of the weight of the insect. The urine has the usual high concentration of potassium; except for phosphate the other inorganic components are present in lower concentration than in the haemolymph. Urine is produced at a rate of about 6 mm.3/hr., implying complete turnover of the water of the haemolymph every 24 hr. Except for a slight (20%) decrease in potassium concentration the composition of the haemolymph remains constant during fasting. The regulatory powers of the excretory system have been tested by injecting NaCl and KCl into the haemolymph and are shown to be relatively feeble.
Studies On the Myoneural Physiology of Echinodermata
Authors: Pople Walter , Ewer D. W. 
Published: April 2021

ABSTRACT
The properties of a neuromuscular preparation of the mid-ventral pharyngeal retractor muscle of Cucumaria sykion (Lampert) have been previously described (Pople & Ewer, 1954). When excited by stimulation of the radial nerve, this muscle shows a double response consisting of a quick component, tentatively attributed to direct nervous paths through the motor complex of the muscle and a delayed component which possibly arises from secondary paths within the motor complex itself. This characteristic double response can be clearly seen in the contractions recorded in the upper trace of Fig. 2 of the present paper. The tension developed by this muscle is dependent upon the intensity of stimulation applied to the radial nerve. No evidence of frequency sensitive facilitation at the myo-neural junction was found.
Cutaneous Respiration in Woodlice
Authors: Edney E. B. , Spencer J. O. 
Published: April 2021

ABSTRACT
Oxygen uptake and carbon dioxide output were measured in the woodlice Ligia oceanica, Oniscus asellus, Porcellio scaber and Armadillidium vulgare, in moist and in dry air, using normal animals and animals whose pleopods had been blocked by emulsion paint. In moist air, the rate of oxygen uptake which occurred through the general integument in animals whose pleopods had been blocked was about 50 % of normal in Ligia and Oniscus, but less than this in Porcellio and Armadillidium. After exposure to moving dry air, oxygen uptake in dry air was below normal in intact animals and nearly ceased in animals with blocked pleopods. Both showed a somewhat higher uptake if the oxygen tension was raised. Carbon dioxide output in moist air was not immediately inhibited by blocking the pleopods, suggesting free diffusion through the integument. Output fell during the first hour, but the R.Q. remained above 1 in all species. Survival times of blocked animals in moist air corresponded qualitatively with rates of oxygen absorption in the four species. In dry air survival was further curtailed, but prolonged again by an increased oxygen tension. Blocked animals of all species survived for a shorter time in moist nitrogen than in moist air. Injection of reduced indigo showed that oxygen was absorbed by intact animals through the thin ventral integument and bases of the legs in Ligia, and to a lesser extent, through the ventral abdominal integument in Oniscus and Porcellio. The ecological implications of these results are discussed, particularly with reference to the relation between survival and humidity. The dehydration death point is probably affected by the level of oxygen deficit and vice versa. A water-permeable integument is of value for respiration as well as for temperature control, but restricts the habitat range of terrestrial animals.
Factors Affecting the Temperature Excess of Insects in Sunshine
Authors: Digby Peter S. B. 
Published: April 2021

ABSTRACT
The temperature excess developed by insects under known radiation strength equivalent to sunshine has been studied in relation to modifying factors in a wind tunnel in the laboratory. Temperature excess was measured by a thermocouple unit in the larger insects, and by the increase in rate of wing beat in Drosophila. Temperature excess varied directly with radiation strength. For insects of breadth greater than 0·3 cm. spectral composition of radiation over the normal sunshine range was of negligible importance to the temperature excess. The effect of colour on the temperature excess was slight. Absorptivity was estimated by comparing temperatures of normal and black-painted insects. Some insects were hotter in the normal state because of change in the site of absorption of heat. White-painted insects were 64−85 % as hot as when black painted, because the white paint still absorbs infra-red radiation. Temperature excess varied with a power of the size between 0·7 and 0·4 in the plasticine spheres, according to size. Temperature excess of the locust type varied as about the 0·4 power of the size ; of the Diptera-Hymenoptera type, as about the 1·0 power. Size for size, compared with the spheres, the locust became between half as hot again and twice as hot, and the Diptera-Hymenoptera type between half as hot again and three times as hot, as the plasticine spheres. Temperature excess varied inversely as the square root of the wind speed above speeds of 20−30 cm./sec. and tended to become independent at lower speeds, with the transition between forced and natural convection. The latter condition will be more important close to the ground. Temperature rise by flight activity is not additive to temperature rise from radiation because it is associated with extra cooling. Evolution of insects from the type of the Orthoptera to the Diptera and Hymenoptera has been associated with the attainment of greater temperature excess for given body size. This is probably of selective significance.
Ionic Regulation and Water Balance in the Aquatic Larva of Sialis Lutaria
Authors: Shaw J. 
Published: April 2021

ABSTRACT
The electrolyte composition of the blood, tissues and excretory fluid of the aquatic larvae of Sialis lutaria has been measured, and the regulation of the concentrations of sodium, potassium and chloride in the blood studied in detail. In the normal larvae these ions are not present in the excretory fluid. Potassium and, perhaps, sodium are reabsorbed in the rectum but chloride is never present in the rectum. If these ions are present in the outside medium they are taken into the larvae through the gut. The blood concentration is regulated by the excretion of these ions via the rectal fluid. Potassium is rapidly excreted but chloride tends to be retained in the blood. Sodium is removed more rapidly than chloride. Water enters the larvae by osmosis through the cuticle, but can also be absorbed through the gut by osmosis or together with sodium ions. The water intake is balanced by excretion of rectal fluid. The factors affecting the rate of water excretion have been studied. The larvae are unable to survive in hypertonic saline solutions. This is due to their inability to make good osmotic water loss or to produce a hypertonic excretory fluid.
The Cortical Changes on Fertilization of the Sea-Urchin Egg
Authors: Kacser H. 
Published: April 2021

ABSTRACT
The cortical changes which may be observed when the sea-urchin egg is fertilized have been the subject of a considerable number of investigations. The results have been discussed in relation to the problem of activation, and a number of conflicting views appear to be held at the moment. Three main lines of investigation give information on these processes. These are: (1) the kinetics of propagation in fertilized eggs, (2) artificial activation, and (3) the changes in mechanically constricted eggs. In what follows an analysis of the relevant evidence is presented. It will be suggested that a consistent picture of the nature of these processes can be given.
The Covering Reaction of Sea-Urchins
Authors: Millott Norman 
Published: April 2021

ABSTRACT
Lytechinus variegatus (Lamarck) covers the parts of its skin that are exposed to light with fragments taken from its surroundings. The covering is taken up by the tube feet, assisted by the spines, and held in place by the tube feet acting in relays. It may be orientated with respect to the light source. There are indications of adaptability of behaviour where the covering pieces offer resistance to being lifted. Covering is related to light and to diurnal light changes, being assumed in strong light and rejected, after a varying interval of time, in darkness. Both continuous bright light and decreases in light intensity evoke covering. The tube feet react to the same stimuli and the speed of their extension is roughly proportional to the change of intensity. The tendency to cover is increased after a sojourn in darkness and is greater in pale individuals than in dark ones. Urchins can be photosensitized by injection of dyes so that they cover in dim light. The prehension and holding of covering does not involve the oral and aboral nerve rings. The relation of covering to light and environment favours the idea that it acts as a screen against strong light.
Studies in Diurnal Rhythms
Authors: Cloudsley-Thompson J. L. 
Published: April 2021

ABSTRACT
The species of woodlouse investigated are known to stand in the following order as regards the rate of water loss by transpiration : Philoscia muscorum &gt; Oniscus asellus &gt; Porcellio scaber &gt; Armadillidium vulgare. The intensity of the responses of the four species to humidity at room temperature (18+ 2° C.) are compared and are shown to stand in the same order. The intensity increases as desiccation proceeds.
At low temperatures (3 ± 2° C.) the intensities of the reactions to humidity are much reduced and are the same in all species; at higher temperatures (30 ± 2° C.) the humidity responses of Ph. muscorum and O. asellus are again somewhat reduced, and it is suggested that this may be correlated with a lower thermal death-point and the need to effect a reduction in body temperature by evaporation.
The antennal cone sensillae are shown to be contact chemo-receptors ; no specific sense organs are concerned with the appreciation of humidity. The response is correlated with saturation deficiency rather than with relative humidity and is probably engendered by dehydration. Ph. muscorum is the most strongly photonegative of the species and there is a graduation through O. asellus and P. scaber to A. vulgare which is the least so.
Ph. muscorum is also shown to be the most intensely nocturnal in habit, A. vulgare the least. It is therefore suggested that the degree of nocturnal activity is correlated with the ability to withstand water loss by transpiration. The results obtained are discussed in relation to the ecology of the species.
Further Observations on Co-Ordination and the Determination of Frequency in the Peristomial Cilia of Stentor
Authors: Sleigh M. A. 
Published: April 2021

ABSTRACT
The work described is a continuation of the work on the peristomial cilia of Stentor previously reported (Sleigh, 1956). The same methods were used in making the observations. A cut across the peristome row of cilia did not affect the wave velocity, but the frequency distal to the cut was usually altered. In twenty-two cases the distal frequency was decreased, and in seven cases it was increased. Cilia in the gullet region are smaller and closer together than those in the main part of the row; these cilia show the same frequency as the other cilia, but a smaller wavelength and wave velocity. The number of cilia in every metachronal wave of the row is the same, as is the number of cilia stimulated in unit time by a single metachronal impulse in any part of the row. The wave velocity is dependent on the number of cilia through which the conduction is passed. The transmission is thought to be the result of a rapid conduction process between the cilium bases and a slower build-up of an excitatory state in the cilium. The frequency of a group of cilia is dependent upon the activity of a pacemaker at the beginning of the group; this pacemaker is probably a cilium with a suitable rate of beat. Frequency is limited by the rate of stimulation or the rate of contraction, whichever is the slower. It is suggested that there are some five excitation stages in the excitation of each cilium, and that each stage takes about 1 msec.; this is comparable with the delay at a nerve synapse. The results of these experiments and observations on ciliary activity indicate that the pacemaker and transmission properties of ciliated tissues and cardiac muscle are comparable in many respects.
Structure and Function in the Nematodes: Internal Pressure and Cuticular Structure in Ascaris
Authors: Harris J. E. , Crofton H. D. 
Published: April 2021

ABSTRACT
No one who has made even a casual study of the Nematoda can fail to have been struck by the extraordinary similarity in form and organization between the very large number of species, genera, orders and families which constitute this class of the very diversiform phylum Aschelminthes. Though there are species which show some variation from the normal ‘nematode facies’, they are few in number and merely seem to emphasize still further the great uniformity of the group as a whole. The characteristic features of the nematodes are present in fresh-water, marine and parasitic forms; they are largely independent of size, of diet and of stage of development.
The Effect of Humidity on the Activity of Tsetse Flies
Authors: Bursell E. 
Published: April 2021

ABSTRACT
Preliminary to an investigation of the water balance of tsetse flies some experiments were carried out to determine the effect of humidity on general activity. Observations previously made on this aspect of behaviour (Jack, 1939; Mellanby, 1936) have been too cursory to admit of general conclusions.
An Interferometric Method of Quantitative Analysis of Antigen-Antibody Reactions in Gels
Authors: Easty G. C. , Ambrose E. J. 
Published: April 2021

ABSTRACT
A sensitive interferometric method of observing antigen-antibody complexes formed by diffusion of the reactants through gels in suitable diffusion cells is described. Bands of antigen-antibody complex, if not too dense, are observed as peaks in the interference fringes, the areas under the peaks being proportional to the quantities present in each band. The method may be made quantitative by measurement of the areas under the peaks of bands in which precipitation has not progressed too far, and by dissolving the bands of dense precipitate by diffusion of a suitable reagent to give peaks in the fringes. An equation expressing the quantity of precipitate present in a band has been derived.
The Relationship Between the Diurnal Light Cycle and the Time of Ovulation in Mice
Authors: Braden A. W. H. 
Published: April 2021

ABSTRACT
The period required for the completion of ovulation in groups of mated females has been studied in 615 mice from three random-bred stocks (L, C and PCT) and in 137 mice of mixed origin. The mice were examined after having been kept for some time under one of four different diurnal light cycles, viz. the natural diurnal light cycle in Edinburgh in December (1) and in June (2) and artificial, reversed, light cycles of 10 hr. darkness/14 hr. light (3) and 4 hr. darkness/2O hr. light (4).
The variation between mice in any one group was greatest when they were maintained under the cycles that had a relatively long dark phase: a period of 12·14 hr. was required for ovulation in groups of L and C stock mice under cycles with a dark phase of 10·15 hr. whereas groups of similar females maintained under cycles with a 4·6 hr. dark phase required only 8·9 hr. for ovulation. Probit analysis indicated that this difference was statistically significant.
In changing the length of the dark phase of the diurnal cycle the beginning of each phase was altered by 3−412 hr.; the mid-points of each phase were altered by less than 1 hr. The results suggest that the mid-point of the ovulation period was determined more by the mid-point of the dark phase than by its onset or completion.
Differences noted between stocks of mice in the mid-point of the ovulation period and in the ability to adjust quickly to an altered light cycle gave indication that the neural mechanisms involved in the control of the time of ovulation in mice are modified according to the genetic constitution of the animal.
The mean interval between coitus and ovulation in females of L and C stocks under natural light cycles was found to be approximately 5 hr. The average time required for the ovulation of three-quarters of the total number of eggs shed in any one mouse (mean 11-12 eggs) was estimated as 0-5 hr.
Experimental Production of Midgut Tumours in Periplaneta Americana L
Authors: Harker Janet E. 
Published: April 2021

ABSTRACT
Sub-oesophageal ganglia taken from Periplaneta americana L. which had been kept in reversed conditions of light and darkness have been implanted into the abdomens of cockroaches living in normal light: dark conditions. When implantation was continued for 4 days transplantable tumours appeared by the eighteenth day in the midgut of the majority of cockroaches. No tumours appeared in the guts of cockroaches when the implanted sub-oesophageal ganglia had been taken from animals kept in normal conditions of fight and darkness, nor when brains or corpora allata were implanted. Injection of an extract of five sub-oesophageal ganglia in 0·05 ml. Ringer solution produced tumours only when injection took place during the inactive phase of the 24 hr. locomotory rhythm.
The Co-ordination of the Responses of Cerianthus (Coelenterata)
Authors: Horridge G. A. 
Published: April 2021

ABSTRACT
Cerianthus membranaceus, as commonly available at Naples, is a brownish polyp which can extend to 15–20 cm. and contract to 5–7 cm. The numerous tentacles are less contractile, being usually 3-5 cm. long. The gross anatomical structure is well described by Hyman (1940). The polyp normally lives in a soft tube, which it secretes, and has no foot or sphincter muscle. Lacking the diversity of muscle groups of a typical sea anemone its movements are very restricted. In contrast to other coelenterate polyps the Ceriantharia have a substantial ectodermal musculature of the column, which is responsible for the vigorous withdrawal of the animal into its tube. There are also ectodermal radial fibres on the disk. Endodermal muscles are relatively insignificant and play no part in the responses considered here. In common with all other coelenterate polyps Cerianthus has two kinds of rapid response to external changes: the feeding movements and the protective retraction. In Cerianthus the two are aroused by different stimuli, and in part they are effected by different muscles. The present study is an analysis of some of the physiological properties of the pathways which co-ordinate these responses.
Superpregnancy in the Mouse
Authors: McLaren Anne , Michie Donald 
Published: April 2021

ABSTRACT
Superovulation was induced by gonadotrophin treatment in adult and immature female mice. The uteri of treated females and of control, naturally ovulating females were examined at 712 days post coitum by means of a laparotomy operation, and again at autopsy 1812 days post coitum. The mating rate of the two older groups of treated immature females was significantly higher than that of either the two younger groups or the treated adults. The proportion of mated females which became pregnant was low in the youngest group, but increased rapidly with age up to the control adult level. The mean number of implants per uterine horn in treated females in which implantation occurred was about twice that found in untreated control females, and did not vary with age. On the other hand, the variation in the number of implants per uterine horn was significantly greater among adult treated than among immature treated females. Total failure of pregnancy through death or disappearance of the embryos was most common among younger females with very large numbers of implants. Partial litter loss through death of individual embryos was greater in adult treated than in immature treated females. Combining partial and total litter loss, the gross mortality rate of embryos was independent of the age of the mother. Death of individual embryos before day 10 was more common in treated than in untreated females, and more common in adult treated than in immature treated females. The incidence bore no relation to the total number of implants either per female or per uterine horn, did not affect the survival of the remaining implants, and was not reduced by progesterone treatment. The death rate of individual embryos during the middle period of pregnancy did not significantly exceed the control level until the number in the horn rose above eight, at which point it increased abruptly in all treated groups. In the immature, but not in the mature, treated females the presence of more than eight implants in both horns was associated with still higher mortality. Death of individual embryos during the later part of pregnancy occurred relatively rarely and was associated with crowding of the uterine horn. In adult treated females which were allowed to go to term, the number of young born alive was inversely related to the number of embryos which had implanted. Our results are discussed with reference to the possibility of artificially increasing the reproductive output of mice and other mammals.