bluuebunny/crossref_metadata_2025 huggingface dataset:
Independent and conjugate eye movements during optokinesis in teleost fish
Authors: Fritsches Kerstin A. , Marshall N. Justin
Published: April 2021

In response to movements involving a large part of the visual field, the eyes of vertebrates typically show an optokinetic nystagmus, a response in which both eyes are tightly yoked. Using a comparative approach, this study sets out to establish whether fish with independent spontaneous eye movements show independent optokinetic nystagmus in each eye. Two fish with independent spontaneous eye movements, the pipefish Corythoichthyes intestinalisand the sandlance Limnichthyes fasciatus were compared with the butterflyfish Chaetodon rainfordi, which exhibits tightly yoked eye movements. In the butterflyfish a single whole-field stimulus elicits conjugate optokinesis, whereas the sandlance and pipefish show asynchronous optokinetic movements. In a split drum experiment, when both eyes were stimulated in opposite directions with different speeds, both the sandlance and the pipefish compensated independently with each eye. The optokinetic response in the butterflyfish showed some disconjugacy but was generally confused. When one eye was occluded, the seeing eye was capable of driving the occluded eye in both the butterflyfish and the pipefish but not in the sandlance. Monocular occlusion therefore unmasks a link between the two eyes in the pipefish, which is overridden when both eyes receive visual input. The sandlance never showed any correlation between the eyes during optokinesis in all stimulus conditions. This suggests that there are different levels of linkage between the two eyes in the oculomotor system of teleosts, depending on the visual input.
Song discrimination by male cicadas Cicada barbara lusitanica(Homoptera, Cicadidae)
Authors: Fonseca P. J. , Revez M. A.
Published: April 2021

Cicada barbara lusitanica males presented a stereotyped singing response behaviour when exposed to a playback of the conspecific song. Males preferred (as measured by the time taken to sing) the conspecific signal to heterospecific songs that differed markedly in temporal pattern. Manipulation of the gross temporal pattern of C. barbara calling song significantly reduced stimulus attractiveness. Indeed, C. barbaramales stopped responding to stimuli in which the temporal pattern approached the characteristic C. orni song, a sympatric and closely related species. If present in females, the preference for stimuli with pauses not exceeding 30 ms could reflect the evolution of a behavioural pre-copulatory isolating mechanism based on song analysis. Males discriminated frequencies within 3-15 kHz, clearly preferring 6 and 9 kHz; both these frequencies matched the main spectral peaks of the song. The preference for specific frequencies was not associated with maximum neuronal excitation as estimated by auditory nerve recordings, which suggests that this frequency-dependent behaviour is not based on the strength of the auditory system's response to different frequencies. Rather, it is likely to reflect fine frequency resolution in the central nervous system.
Serotonin sets the day state in the neurons that control coupling between the optic lobe circadian pacemakers in the cricketGryllus bimaculatus
Authors: Saifullah A. S. M. , Tomioka Kenji
Published: April 2021

The bilaterally paired optic lobe circadian pacemakers of the cricket Gryllus bimaculatus mutually exchange photic and circadian information to keep their activity synchronized. The information is mediated by a neural pathway, consisting of the so-called medulla bilateral neurons,connecting the medulla areas of the two optic lobes. We investigated the effects of serotonin on the neural activity in this coupling pathway. Spontaneous and light-induced electrical activity of the neurons in the coupling pathway showed daily variations, being more intense during the night than the day. Microinjection of serotonin or a serotonin-receptor agonist,quipazine, into the optic lobe caused a dose- and time-dependent inhibition of spontaneous and light-induced responses, mimicking the day state. The amount of suppression was greater and the recovery from the suppression occurred faster during the night. Application of metergoline, a non-selective serotonin-receptor antagonist, increased spontaneous activity and light-evoked responses during both the day and the night, with higher effect during the day. In addition, metergoline effectively attenuated the effects of serotonin. These facts suggest that in the cricket's optic lobe, serotonin is released during the daytime and sets the day state in the neurons regulating coupling between the bilaterally paired optic lobe circadian pacemakers.
Basic limb kinematics of small therian mammals
Authors: Fischer Martin S. , Schilling Nadja , Schmidt Manuela , Haarhaus Dieter , Witte Hartmut
Published: April 2021

A comparative study of quantitative kinematic data of fore- and hindlimb movements of eight different mammalian species leads to the recognition of basic principles in the locomotion of small therians. The description of kinematics comprises fore- and hindlimb movements as well as sagittal spine movements including displacement patterns of limb segments, their contribution to step length, and joint movements. The comparison of the contributions of different segments to step length clearly shows the proximal parts (scapula,femur) to produce more than half of the propulsive movement of the whole limb at symmetrical gaits. Basically, a three-segmented limb with zigzag configuration of segments is mainly displaced at the scapular pivot or hip joint, both of which have the same vertical distance to the ground. Two segments operate in matched motion during retraction of the limb. While kinematic parameters of forelimbs are independent of speed and gait (with the scapula as the dominant element), fundamental changes occur in hindlimb kinematics with the change from symmetrical to in-phase gaits. Forward motion of the hindlimbs is now mainly due to sagittal lumbar spine movements contributing to half of the step length. Kinematics of small therian mammals are independent of their systematic position, their natural habitat, and also of specific anatomical dispositions (e.g. reduction of fingers, toes, or clavicle). In contrast, the possession of a tail influences `pelvic movements'.
The Time of Action of the Gene Antennaless and its Effect on the Development of the Cephalic Complex of Drosophila Melanogaster
Authors: Begg Michael , Sang James H.
Published: April 2021

A. The development of the antenna buds of the mutant antennaless of D. melanogaster has been examined and it is shown that: Prior to about 70 hr., no histological difference is detectable as between normal and abnormal anlagen. Normal antenna buds continue to grow exponentially after 70 hr. ; abnormal buds scarcely grow at all. The abnormal bud is also distinguished from wild type by its failure to segment. Both normal (ant. +) and antennaless (ant. −) frontal sacs are everted normally in the pupa. B. The period during which the course of development of antennaless buds of the same genotype could be modified by specific nutritional substances was also determined. It is shown that media containing a high concentration of dextrose will induce a lowered exhibition. By transferring larvae from normal media to media of high dextrose content, it is found that the course of development of the antenna bud cannot be modified after about the 80th hr. of larval life.

These experiments suggest that the effective period of the gene is relatively short and is probably not more than 12 hr. for each individual larva. This period corresponds to the T.E.P., butis not necessarily identical with ‘the time of action of the gene’.
Oxygen Consumption of Prepupae of Drosophila Melanogaster Meigen, in Relation to the Surface Area of the Puparium
Authors: Ellenby C.
Published: April 2021

A method is described by means of which the surface area of puparia of Drosophila melanogaster may be measured. Measurement of almost 200 puparia showed that the relationship between surface area, per mg., and body weight could best be expressed in the form Of the equation S = 7·7049 – 2·1099X, where S = sur-face area, sq. mm. per mg. wet weight, for prepupae of mean wet weight X mg. As the standard error of estimate, ±0·117, is equal to only 2·2% of the mean surface area per mg., the surface area can be accurately estimated from the wet weight. The prepupal oxygen consumption, per mg. wet weight, is shown to decrease steadily with increasing body weight ; with an increase in mean wet weight from 0·847 to 1·700 mg., the oxygen consumption, per mg., decreases by about 50%. Utilizing the above regression equation, the surface area of prepupae of known oxygen consumption was estimated and thus the oxygen consumption per sq. mm. of body surface. These values show no significant variation with increasing body weight, so that it can be concluded that the oxygen consumption of prepupae of D. melanogaster is proportional to the surface area.
Some Observations on The Physiology and Pharmacology of the Nerve Endings in the Crop and Gizzard of the Earthworm, With Special Reference To The Effects of Cooling
Authors: Ambache N. , Dixon A. ST J. , Wright E. A.
Published: April 2021

The use of the crop and gizzard of the earthworm as a convenient smooth-muscle preparation was first suggested by Mines (1907). The pharmacological properties of this preparation have recently been described by Wu (1939). His experiments and Millott’s (1943) have shown that the digestive tract of the earthworm, including the crop and gizzard, is reciprocally innervated. The nerve fibres concerned are cholinergic in the augmenter and adrenergic in the inhibitory nerves.
The Cuticular Lipoids of Insects
Authors: Beament J. W. L.
Published: April 2021

The ability of insects to withstand desiccation was shown by Kühnelt (1928) to be due to the epicuticular layer of the cuticle. This outermost part was found to be highly resistant to strong acids and was shown, by chemical tests, to contain fatty acids and cholesterol type molecules. Wigglesworth (1933) described a complex fatty or waxy substance in the upper layers of the cuticle which he called ‘cuticulin’ ; Pryor (1940) found that this lipoid is entirely confined to the epicuticular layer, suggesting that it is used to impregnate a tanned protein. Lipoid material has also been extracted from the exuviae of the silkworm Bombyx mori (Bergmann, 1938). Bergmann found that hot alkali merely fused the epicuticle into oily droplets suggesting that saponification was taking place. The extract so obtained was a brown waxy substance, forming about 4% of the total weight of the cuticle, and it consisted of paraffins, saturated aliphatic acids and esters. A more detailed study of the waxes of certain insects specialising in wax formation has been given by Chibnail, Piper, Pollard, Williams & Sahai (1934b) ; Chibnall, Latner, Williams & Ayre (1934a), and Blount, Chibnall & el Mangouri (1937). All these substances were complicated mixtures of alcohols, acids, paraffins and esters with chain length of the order of C30.

Hurst (1941) has suggested that the asymmetry of the insect cuticle is regulated by the ‘outer free lipoid’. He postulates a cuticle surface in the form of a lipoprotein mosaic.

It is the object of this study to investigate the distribution and properties of these lipoid materials, to obtain evidence of the structure of the epicuticle by comparison of in vitro phenomena with those of living insect cuticle, and to indicate the function of lipoids in resisting the action of certain insecticides.
Studies on the Organizer Problem in Pelmatohydra Oligactis: I. The Induction Potency of the Implants and the Nature of the Induced Hydranth
Authors: Yao T.
Published: April 2021

The existence of a physiological gradient in Hydra has been repeatedly demonstrated by a number of investigators, and the hypostome, which is supposed to be the region of highest metabolic activity, has generally been regarded as the organization centre of the animal. Earlier transplantation experiments (Browne, 1909; Rand, Bovard and Minnich, 1926; Mutz, 1930) indicated that when a piece of hypostome is grafted, it can act as an organizer and induce a new hydranth. Although these are all well-known facts, the underlying mechanism in the induction process remains obscure. The present work is the first step in an attempted physiological analysis of the problem, with special reference to the induction potency of implants derived from different body levels, and to the nature of the induced hydranth.
Studies on the Organizer Problem in Pelmatohydra Oligactis: II. The Effect of Some Respiratory Inhibitors and Stimulants and of Oxygen Deficiency on the Induction Potency of the Hypostome
Authors: Yao T.
Published: April 2021

In a previous communication (Yao, 1945(a)) it has been shown that only the material of the hypostome, when used as implant, has the properties of an organizer; such a graft is able to induce a new hydranth, in which the hypostome is developed from the implant itself, while the rest, including tentacles and body proper, is derived from the host. Supposing the induction process to be evoked by some active substance present in the organizer, this active substance, as well as the initial act of induction, might be modified by those agents which inhibit or stimulate respiration. The present paper deals with the effect of certain respiratory inhibiting and stimulating agents on the induction ability of the hypostome. The effect of oxygen deficiency on induction will also be described.

The details of the method used will not be described, since these were essentially similar to those given in the former paper.
Studies On the Organizer Problem in Pelmatohydra Oligactis
Authors: Li H. P. , Yao T.
Published: April 2021

Determination of the hypostome occurs very early in the development of a bud (our stage 1) in Pelmatohydra oligactis. The mode of induction by a developing hypostome (type II) is different from that by an adult hypostome (type I). In the former case, an implant always induces a long tube-like outgrowth before any tentacle rudiment becomes visible. In the latter case,.simultaneous induction of tentacles and body takes place. Frequently, tentacle rudiments appear before visible differentiation of the body. Type II induction is characteristic of developing hypostomes from some phase of stage 1 up to a stage at which the bud possesses short, but non-motile tentacles (our stage 4). As soon as the detachment of a young polyp from the parent occurs, there is a sudden change in the mode of induction, from type II to type I. Possible explanations of the course of differentiation in the hypostome and of the transition between the two types of induction are suggested.
The Sickling Phenomenon and its Bearing on the Problem of Red Cell Structure
Authors: Ponder Eric
Published: April 2021

In considering the various forms of disk-sphere transformation which mammalian red cells undergo, reference has repeatedly been made to the ideas of Norris, Gough, Teitel-Bernard and others who have suggested that the discoidal form of the cell is the result of an equilibrium between two sets of forces, one expansive, and the other (which includes surface tension) conducing to contraction of the surface (Norris, 1882; Gough, 1924; Teitel-Bernard, 1932; Ponder, 1929, 1934, 1936, 1937, 1939, 1941, 1942 a, b, c;Furchgott, 1940a, 19406; Furchgott & Ponder, 1940, 1941). When the disk changes into the sphere, we are dealing with a diminution or disappearance of the ‘expansive force’ which is probably due to a modification or even a destruction of a surface ultrastructure, and in the absence of anything to oppose it, the tension at the cell-fluid interface determines that the cell takes up the spherical form in which the surface is a minimum for the volume. As will be seen below, other forces are probably operative in the same direction. A re-establishment of the ultrastructure, with the ‘expansive forces’ inherent in its molecular arrangement, leads to the transformation of the sphere into the original disk, and the various conditions under which this reversal can be brought about have already been described. We have now to consider a situation in which the ‘expansive forces’ are so great, or the forces resisting them so small, that the red cell assumes a series of shapes which are characterized by extension, just as the spherical form is characterized by contraction.
The Mechanism of Locomotion in Gastropod Molluscs
Authors: Lissmann H. W.
Published: April 2021

As is the case in all terrestrial animals, the progression of a snail or other gastropod depends on the exercise by the animal of an adequate force directed posteriorly against the ground ; in an animal moving horizontally and at constant speed, this force overcomes the frictional resistance encountered by the parts which are gliding forwards. The movements of the pedal surface of some gastropods have been discussed in a previous paper (Lissmann, 1945). The experiments described below were designed to correlate these movements with the forces set up during locomotion. The salient point which appears to be established is that during progression the foot exhibits (i) areas of forward motion, coinciding with phases of longitudinal muscular contraction, followed by extension ; (ii) areas at rest, which remain essentially elongated. However, the state of the muscles is no indication of the tensions they may set up within the body, nor of the propulsive force they may exert; it is by no means obvious how the external forces are produced, or how they lead to progression.
The Fermentation of Carbohydrates in the Rumen of the Sheep
Authors: Elsden S. R.
Published: April 2021

Acetic, propionic and butyric acids are the main volatile fatty acids in the rumen of the sheep. Acetic acid accounts for 55 –75 % of the total. Cellulose, glucose and lactic acid are rapidly fermented in vitro by rumen contents with the production of acetic, propionic and butyric acids. Propionic acid is the major component in all cases : very little if any butyric acid is formed from cellulose. The in vitro fermentation of glucose closely resembles the in vivo. The in vitro fermentation of dried grass yields the same three acids, but with acetic acid predominating. Members of the genus Propionibacterium have been isolated from the rumen, and evidence is presented to show that these organisms are responsible for the production of the propionic acid found in the rumen. The dietary history of the animal is shown to influence the rate at which glucose is fermented in the rumen, and the composition of the rumen microflora.
The Dietetics of the Clothes Moth, Tineola Bisselliella Hum.
Authors: Fraenkel G. , Blewett M.
Published: April 2021

Much attention has been paid in the past to the peculiar mechanism of keratin digestion which enables the clothes moth to infest woollen materials (Schulz, 1925 ; Lipderstnøm-Lang & Duspiva, 1935 ; Duspiva, 1936), but little is known about its general food requirements. It is known that the larvae will not grow on clean wool (Titschak, 1922; Crowell & McCay, 1937) and that damage to clothing is generally restricted to parts soiled by dirt and sweat. On the other hand, Tineola has been bred in the laboratory on various foods in the absence of keratin, and there are no indications that keratin is a necessary constituent of the food (Titschak, 1922). A study of some aspects of the nutrition of Tineola has been made by Crowell & McCay (1937) and will be discussed below.
The Dietetics of the Caterpillars of Three Ephestia Species, E. Kuehniella, E. Elutella, and E. Cautella, and of a Closely Related Species, Plodia Interpunctella
Authors: Fraenkel G. , Blewett M.
Published: April 2021

In the course of a previous analysis of the dietetics of several insects found on dried foods (Fraenkel & Blewett, 1943 a), it was discovered that the larva of Ephestia kuehniella, which normally feeds on flour, grew badly, unlike the larvae of several beetles, on artificial diets consisting of casein, glucose, cholesterol and salts and the moths failed to emerge. Later the investigation was extended to E. elutella, which is known to infest such divergent materials as grain, tobacco, cacao beans and dried fruit. E. elutella grew fairly well on artificial diets, but again the moths failed to emerge from the pupae. Here the work was held up until it was discovered that Ephestia required, for successful growth and metamorphosis, fat-soluble factors which can be supplied with wheat-germ oil (Fraenkel & Blewett, 1945). In the present paper, which mainly deals with the requirements for carbohydrates, sterols and vitamins of the B complex, most of the diets described contain wheat-germ oil. An analysis of the factors concerned in wheat-germ oil will be given in the following paper.
Linoleic Acid, Vitamin E and Other Fat-Soluble Substances in the Nutrition Of Certain Insects, Ephestia Kuehniella, E. Elutella, E. Cautella and Plodia Interpunctella (Lep.)
Authors: Fraenkel G. , Blewett M.
Published: April 2021

In a previous publication (Fraenkel & Blewett, 1943) it has been shown that a number of insects which normally live on wholemeal flour or other cereal products grow badly or not at all on flour thoroughly extracted with chloroform unless a sterol, e.g. cholesterol, is added to the diet. For several beetle larvae the diet becomes optimal upon addition of a pure sterol, but for the caterpillars of a moth, Ephestia kuehmella, wheat-germ oil has a much better effect than a sterol. Using artificial diets, consisting of glucose, casein, yeast and cholesterol, it was found that E. kuehmella grew well in the presence of wheat-germ oil and badly without it. Subsequently it emerged (Fraenkel & Blewett, 1946b) that the closely related species E. elutella grew fairly well on similar diets in the absence of wheat-germ oil and pupated normally, but the adults invariably failed to emerge from the pupae. With wheat-germ oil, growth was fast and emergence normal. Analysis of the factors in wheat-germ oil which are required by the moths of the genus Ephestia is the subject of the present paper. Some of the results have already been shortly reported (Fraenkel & Blewett, 1945).
The Influence of Peripheral Connexion on the Diameter of Regenerating Nerve Fibres
Authors: Sanders F. K. , Young J. Z.
Published: April 2021

Stretches of regenerating rabbit’s nerve in which no connexion with the periphery is allowed contain numerous and small nerve fibres. Both cutaneous sensory and motor nerve fibres become large when allowed to reach their endorgans, but the motor fibres attain greater diameters than the cutaneous sensory fibres. Motor fibres regenerating without opportunity of reaching muscle fibres become little if any larger than sensory fibres when both are unable to reach their end-organs. It is, therefore, probable that the peripheral connexion is of great importance in determining fibre diameter. The fibres of the central stump of a nerve regenerating unconnected with the periphery remain small and have relatively very thick myelin sheaths. The diameter of nerve fibres regenerated in the region below a crushed point on a nerve is not influenced by the length of nerve to be regenerated distally. Increase of diameter and medullation proceeds centrifugally from a lesion, more distant points showing a lesser degree of maturation at any given time. Fibres regenerated in a grafted piece of posterior tibial nerve were only slightly smaller than those in a grafted piece of peroneal nerve. Connexion with the periphery is, therefore, able to produce an increase in fibre diameter which overrides any constriction of fibre growth produced by the slightly smaller Schwann tubes.
Studies on Temperature Regulation
Authors: Kirk R. L. , Hogben Lancelot
Published: April 2021

The upper thermal death-point of the slow worm (Anguis fragilis) is significantly above that of either the toad (Bufo bufo) or the frog (Rana temporaria). That of the toad differs only slightly from that of the frog. In response to external variation with respect to temperature and humidity, the body temperature of the toad behaves in a manner similar to that of the frog, being considerably below that of the air at low humidities, though appreciably above that of the wet-bulb thermometer. It is concluded that the toad loses water as freely as the frog. The body temperature of the slow worm and that of the alligator (A. mississippiensis) differs only slightly from that of the air under all conditions of sustained air temperature and humidity. The body temperature reaction of the alligator is more sluggish than that of the slow worm, pre-sumably owing to the higher thermal capacity of the animal. The significance of these results in relation to the evolution of the terrestrial vertebrates is discussed. It is suggested that homoeothermic stocks could arise only from reptiles of relatively small size, and that large body size would militate against survival during periods of low mean external temperature.
A Micro-Respirometer for Single Prepupae of Drosophila Melanogaster Meigen
Authors: Ellenby C.
Published: April 2021

An apparatus is described, of the Gerard-Hartline type, suitable for the measurement of the oxygen consumption of single pupae of Drosophila. The design is such that the oxygen consumption of twelve separate animals can be conveniently measured simultaneously.
Fertilizing Capacity of Spermatozoa Following Cold Treatment of the Scrotal Testes of Rabbits
Authors: Chang Min Chueh
Published: April 2021

The fertility or sterility of a male depends on several factors, among which are the chemical constituents of the semen, the number, morphological integrity, motility, metabolism and viability of the spermatozoa. These factors, of course, are interrelated in effecting fertility or probability of fertilization.
The Function of the Insect Ocellus
Authors: Parry D. A.
Published: April 2021

Little light is thrown on the function of the insect ocellus by blinding experiments or by a study of its distribution within the class. The ocellus cannot, on optical grounds, receive an image, but can only be affected by changes in intensity of illumination. The ocellar nerves are characterized by a small number of constituent fibres, and by the large diameter of the latter. When the ocellus is darkened, the electrical response in the nerve consists of a decrease in potential near the ocellus, relative to the cut end of the nerve. No impulses were detected in the ocellar nerve. When the ocellus is darkened, or one of the lateral ocellar nerves cut, there is a continuous discharge of nerve impulses in the commissures. This ceased as soon as the ocellus was reilluminated. It is suggested that darkening the ocellus causes depolarization which spreads down the ocellar nerve and depolarizes a ganglion in the brain, thereby inducing the discharge of impulses down the commissures. It is pointed out that this might facilitate reflexes at lower centres, and so accelerate the animal’s response to shadows.
A Metal Micro-Respirometer of the Barcroft Type Suitable for Small Insects and Other Animals
Authors: Crisp D. J. , Thorpe W. H.
Published: April 2021

A Barcroft-type micro-respirometer, made of metal, is described. It is particularly suitable for rapid determination of the respiratory rate of small insects or other animals which can be maintained in air during the course of the experiment. It is especially convenient for experiments in which it is necessary to employ different gas mixtures. Sensitivity is approximately 100 times that of the standard glass Barcroft apparatus. The possible sources of error are considered.
The Function of Haemoglobin in Tanytarsus (Chironomidae)
Authors: Walshe Barbara M.
Published: April 2021

Eighty years ago Lankester(1867) identified spectroscopically the red blood pigment of the larvae of Chironomus plumosus as haemoglobin. Subsequently (1873) he correlated its presence with the fact that they inhabit stagnant ponds and putrescent mud where the amount of accessible oxygen must often be small. Since then it has been generally assumed that their haemoglobin enables the larvae to live in surroundings deficient in oxygen, and experimental evidence for this has lately been supplied by Harnisch (1936) and by Ewer (1942). These workers compared the metabolism of normal larvae with that of larvae whose haemoglobin had been made functionless by conversion to carboxyhaemoglobin. They found that the pigment was only used as an oxygen carrier at low pressures of oxygen; it is used to the greatest extent in water which is 22 % saturated with air at 17° C. Ewer also made a series of measurements of the oxygen content of the pond from which her larvae were obtained and found oxygen concentrations corresponding to 32 % air saturation or less for periods of at least 16 consecutive hours. Thus it may be assumed that in nature the haemo-globin of the species with which Ewer worked is of functional value.
The Succinoxidase System in Oyster Muscle
Authors: Humphrey George Frederick
Published: April 2021

The importance of the role which the C4-dicarboxylic acids play in tissue respiration was pointed out by Szent-Györgyi in 1937. It is now known that succinic dehydrogenase is one of the few dehydrogenases which react directly with the cytochromes, and the ‘succinoxidase’ system has been investigated in a large number of vertebrate tissues. The action of succinate on the oxygen uptake of a few invertebrate tissues has been studied, but no detailed consideration has been given to the possible occurrence of a succinoxidase system. This system becomes especially important in view of the varied response of such tissues to agents like cyanide and azide, which have a marked effect on cytochrome oxidase.
An Electro-Magnetic Mixer for Manometric Experiments
Authors: Laser H. , Rothschild Lord
Published: April 2021

Manometric experiments often involve the addition of substances such as a substrate, an inhibitor, or acid, to the material under investigation.
The urban-adapted underground mosquito Culex pipiens form molestus maintains exogenously influenceable circadian rhythms
Authors: Epstein Natalie R. , Saez Kevin , Polat Asya , Davis Steven R. , Aardema Matthew L.
Published: April 2021

Genes known to affect circadian rhythms (i.e. ‘clock genes’) also influence the photoperiodic induction of overwintering reproductive diapause in the northern house mosquito, Culex pipiens f. pipiens. This suggests that molecular changes in one or more clock genes could contribute to the inability to diapause in a second form of this mosquito, Culex pipiens f. molestus. Temperate populations of Cx. pipiens f. molestus inhabit underground locations generally devoid of predictable photoperiods. For this reason, there could be limited fitness consequences if the hypothesized molecular changes to its clock genes also eliminated this mosquito's ability to regulate circadian rhythms in response to photoperiod variation. Here, we demonstrate that in contrast to this prediction, underground derived Cx. pipiens f. molestus retain exogenously influenceable circadian rhythms. Nonetheless, our genetic analyses indicate that the gene Helicase domino (dom) has a nine-nucleotide, in-frame deletion specific to Cx. pipiens f. molestus. Previous work has shown that splice variants in this gene differentially influence circadian behavior in Drosophila melanogaster. We also find derived, non-synonymous single nucleotide polymorphisms (SNPs) in eight genes that may also affect circadian rhythms and/or diapause induction in Cx. pipiens f. molestus. Finally, four putative circadian genes were found to have no quantifiable expression during any examined life stage, suggesting potential regulatory effects. Collectively, our findings indicate that the distinct, but molecularly interconnected life-history traits of diapause induction and circadian rhythms are decoupled in Cx. pipiens f. molestus and suggest this taxon may be a valuable tool for exploring exogenously influenced phenotypes in mosquitoes more broadly.
Plasticity of non-shivering thermogenesis and brown adipose tissue in high-altitude deer mice
Authors: Coulson Soren Z. , Robertson Cayleih E. , Mahalingam Sajeni , McClelland Grant B.
Published: April 2021

High altitude environments challenge small mammals with persistent low ambient temperatures that require high rates of aerobic heat production in face of low O2 availability. An important component of thermogenic capacity in rodents is non-shivering thermogenesis (NST) mediated by uncoupled mitochondrial respiration in brown adipose tissue (BAT). NST is plastic, and capacity for heat production increases with cold acclimation. However, in lowland native rodents, hypoxia inhibits NST in BAT. We hypothesize that highland deer mice (Peromyscus maniculatus) overcome the hypoxic inhibition of NST through changes in BAT mitochondrial function. We tested this hypothesis using lab born and raised highland and lowland deer mice, and a lowland congeneric (Peromyscus leucopus), acclimated to either warm normoxia (25°C, 760 mmHg) or cold hypoxia (5°C, 430 mmHg). We determined the effects of acclimation and ancestry on whole-animal rates of NST, the mass of interscapular BAT (iBAT), and uncoupling protein (UCP)-1 protein expression. To identify changes in mitochondrial function, we conducted high-resolution respirometry on isolated iBAT mitochondria using substrates and inhibitors targeted to UCP-1. We found that rates of NST increased with cold hypoxia acclimation but only in highland deer mice. There was no effect of cold hypoxia acclimation on iBAT mass in any group, but highland deer mice showed increases in UCP-1 expression and UCP-1-stimulated mitochondrial respiration in response to these stressors. Our results suggest that highland deer mice have evolved to increase the capacity for NST in response to chronic cold hypoxia, driven in part by changes in iBAT mitochondrial function.
The Measurement of the Oxygen Consumption of Daphnia by a Modification of the Cartesian Diver Technique
Authors: O’Connor R. J.
Published: April 2021

The Cartesian diver microrespirometer has been adapted to the measurement of the oxygen consumption of Daphnia. The modification involves an increase in size of the diver to a total capacity of over 100 μl., and absorption of carbon dioxide by sodium hydroxide in a central cup incorporated in the structure of the diver. The variation in the rate of oxygen consumption of normal Daphnia has been measured. Sources of error in the modified technique have been investigated and the possibility of its wider use discussed.
The Flight of Birds
Authors: Brown R. H. J.
Published: April 2021

For many years there has been discussion on the details of the wing movements of birds in flight, and many attempts have been made to produce clear cinematograph records of the flapping cycle. Until recently no photographic system has combined a sufficiently short exposure with a rapid repetition rate and a reasonably large field of view.
The Physiology of Contractile Vacuoles
Authors: Kitching J. A.
Published: April 2021

On transfer from sea water to dilute sea water, the marine peritrich ciliate Vorticella marina swells more rapidly at higher temperatures. It is concluded that the permeability of the surface of V. marina to water is influenced by temperature, with a Q10 of very roughly 2·5–3·2. The body volume of the fresh-water peritrich ciliate Carchesium aselli is maintained approximately constant when the organism is transferred to solutions of sucrose of concentrations up to about 0·04 M; in higher concentrations the organism shrinks. The rate of output of the contractile vacuole of C. aselli decreases with increasing concentrations of sucrose in the external medium; the rate of output is very low in 0·05 M-sucrose. From a consideration of the effects of sucrose solutions on the body volume and on the rate of vacuolar output it is concluded that the initial osmotic pressure of C. aselli normally exceeds that of the external pond water by about 0 0·4–0· 05 M non-electrolyte. The. internal osmotic pressure of C. aselli is not materially increased by increase of temperature. It is concluded that the increase in rate of vacuolar output, which accompanies increase of temperature, counterbalances an increased rate of osmotic uptake of water from the external medium, and that this increased rate of uptake is due to an effect of temperature on the permeability of the surface through which the water enters. The rate of vacuolar output is temporarily much increased when C. aselli, which has been equilibrated in solutions of ethylene glycol, is returned to pond water. It is suggested that the temperature and the osmotic pressure of the external solution largely determine the osmotic stress which is imposed on the organism, and that they thus influence the state of hydration of the protoplasm; in turn this may be supposed to determine the activity of the contractile vacuole.
Studies on Tapeworm Physiology
Authors: Smyth J. D.
Published: April 2021

Plerocercoid larvae of the pseudophyllidean cestode Ligula intestinalis from the body cavity of roach, were cultured in vitro at 40°C. in a variety of saline and nutrient media. About 65% of such cultures were aseptic. During cultivation, larvae produced acid by-products (unidentified) and the pH fell rapidly. The presence of these acid by-products slowed down development, or, if present in sufficient quantity, caused death. In order to obtain development in nutrient media in a period (3 days) comparable to that required in a bird (the normal host) it was necessary to renew the medium 24-hourly. 6% of the eggs produced from a worm cultured in horse serum were fertile. Fertile eggs were never obtained from larvae cultured in any other media. Certain bacterial infections had no apparent detrimental effect on development, but others were toxic. Some larvae underwent development in non-nutrient medium (୴ strength Locke’s solution). The exact conditions under which this occurred was not determined. Fragments (3 cm. long), of larvae or larvae with either scolex or posterior half removed, underwent development to the stage of oviposition in nutrient media. Histochemical examination revealed that the plerocercoid larvae were almost fat-free. During cultivation, very large quantities of cytoplasmic fat were produced the quantity being proportional to the duration of cultivation. Fat was produced even under starvation conditions (i.e. during cultivation in saline) and can be considered a metabolic by-product. The fresh plerocercoid contained great quantities of glycogen in the parenchyma and muscle regions. After cultivation in nutrient or saline media, considerable quantities were still present.
The Swimming of Whales and A Discussion of Gray’s Paradox
Authors: Parry D. A.
Published: April 2021

Whales swim by oscillating the tail and the flukes in a vertical plane. Tail and flukes move out of phase, the flukes leading on the tail by quarter of a wave-length. Photographic evidence is given and anatomical evidence referred to. Previous accounts of the movement are reviewed. A theoretical treatment of the dynamics of swimming gives results in fair agreement with the only known observation of the frequency of tail-beat. Support is given to Gray’s suggestion that the drag of an actively swimming whale is less than that of a rigid model. The possibility that whales develop more power (weight for weight) than man without going into oxygen debt is discussed. It is concluded to be unlikely.
Shape and Shape Transformations of Heated Human Red Cells
Authors: Ponder Eric
Published: April 2021

The action of temperatures above 48° C. on the red cell is usually regarded as a classical example of the irreversible effects of injury, the lysis which follows being attributed to a surface membrane becoming permeable because its lipid components are melted or because its protein components become denatured. Recently it has been found that the effects are considerably more complex, and increasing emphasis is being placed on the role which fragmentation plays in the phenomenon of heat haemolysis. Ham, Shen, Fleming & Castle (1948) have pointed out that the fragmentation which precedes haemolysis results in the cells of the system becoming more and more spherical, so that the extent to which each cell can swell before its surface is stretched becomes less and less, and the tonicity in which it haemolyses becomes greater and greater; when there is sufficient fragmentation, indeed, human red cells will haemolyse even in an isotonic medium such as plasma. The tonicityvolume relations of cells which have lost one or more of these fragments during heating to temperatures in the neighbourhood of 48° C., however, are substantially the same as those of intact cells (Ponder, 1948a), and both cells and fragments show substantially the same resistance to haemolysis by saponin and by digitonin; these observations point to the osmotic properties and the properties which determine the resistance to lysins being shared by cell and fragment, and to the unit structure upon the integrity of which these properties depend being smaller than the intact red cell. The possibility that this is so suggests that something may be learned by examining the shape of the red cells and fragments more closely, since the ability to maintain shape and to undergo shape transformations are also properties which are usually thought of as associated with the red cell as a unit structure.
The Effects of High and Low Temperatures on the Epidermal Mitotic Activity of the Adult Male Mouse, Mus Musculus L
Authors: Bullough W. S.
Published: April 2021

The form of the diurnal cycles of epidermal mitotic activity in the adult male mouse has been shown to be determined by the times of sleeping and waking, high mitotic activity being associated with both natural and artificial sleep, and low mitotic activity with muscular exercise (Bullough, 1948 a, b).
The Pigmentation of Cavernicolous Animals
Authors: Beatty R. A.
Published: April 2021

The visible coloration of three species of amphipod Crustacea (Gammarus pulex, G. marinus and Orchestia gammarella) was found to be due almost exclusively to carotenoid pigments, including in each case a proportion of an astacin-like carotenoid acid. No carotenoid pigments could be demonstrated, even in traces, in three species of the cavernicolous Amphipod genus Niphargus. Carotenoid pigmentation is thought to be characteristic of Amphipoda and would therefore be the ancestral pigment of the cave forms. The lack of pigment in cave Amphipoda may be due to absence of light; it is not due to lack of carotenoid pigments in the food.
The Absorption of Water by the Eggs of Corixa Punctata Illig. (Hemiptera-Corixidae) Under Experimental Conditions
Authors: Banks C. J.
Published: April 2021

Poisson (1924) states that the eggs of aquatic Hemiptera increase in volume as they develop. Kerenski (1930), Ludwig (1932), Evans (1933), Johnson (1937), Roonwal (1936), and Birch & Andrewartha (1942), all have described in various insects the changes which take place in the developing egg and which are generally associated with the absorption of water.
The Utilization of Reserve Substances in Drosophila During Flight
Authors: Wigglesworth V. B.
Published: April 2021

The respiratory quotient in Drosophila during flight is about 1·0 (Chadwick, 1947), and the duration of flight to exhaustion varies with the age of the fly in the same manner as does the total glycogen—increasing steeply during the first 5 days of adult life, remaining at a maximum for about 10 days and then falling gradually until the fly is 5 or 6 weeks old (Williams, Barness & Sawyer, 1943). It appears certain that glycogen is the main or sole reserve substance consumed during flight.

It is the object of the present work to provide a histological picture of the distribution of the reserve substances and their mobilization during sustained flight. In the course of the work it has been possible to compare directly the efficiency of different substances as sources of energy for flight. D. melanogaster has been used throughout. The insects have been reared and maintained on standard maize-meal medium at 250C.
Vascular Patterns of the Mammalian Testis and Their Functional Significance
Authors: Harrison R. G. , Weiner J. S.
Published: April 2021

Even a superficial examination of the testes of various animals, for example rat and rabbit, is sufficient to make obvious that there are fundamental differences in their vascular supply and that the vessels display remarkable complexity both in their venous and arterial course. That morphological differences may exist between different animals has long been realized; thus de Graff (1677) clearly depicts the contrasting patterns of dog and dormouse. Nevertheless, comparative studies of these patterns have been meagre and their functional significance has not been elucidated.

In this communication is presented first a description of these testicular vascular patterns in a number of animals, drawing attention especially to the course and relations of the vessels within the spermatic cord. In a second section evidence is offered in support of the suggestion that the morphology of the blood vessels in the cord is connected with the temperature regulating mechanism of the testis—specifically, as a determining factor of the abdomino-testicular temperature ‘gradient’.
The Kinetics of Locomotion of the Grass-Snake
Authors: Gray J. , Lissmann H. W.
Published: April 2021

The propulsion of an undulating grass-snake, Natrix (Tropidonotus) natrix, depends on the ability of the animal to adopt a sinusoidal form and brace the lateral surface of its body against rigid external objects (Gray, 1946). Under such conditions the forces acting normally to the sides of the body provide a propulsive force equal but opposite to the frictional forces tending to restrain the motion of the animal. The present paper represents an attempt to give quantitative expression to these conclusions by observation of the forces acting against the body of a living snake.
The Nutritional Requirements of Drosophila Melanogaster
Authors: Begg Michael , Robertson Forbes W.
Published: April 2021

Methods are described for the aseptic culture of Drosophila. All the factors necessary for normal development can be extracted from yeast in water-soluble form. A chemically defined medium sufficient for almost normal growth is described and includes : casein (and gelatin) as a source of amino-acids, dextrose, cholesterol, ergosterol, yeast nucleic acid, inositol, biotin, aneurin hydrochloride, riboflavine, nicotinic acid, pyridoxin hydrochloride, Ca-pantothenate, choline chloride, thymine and folic acid. For completely normal development an alkali-soluble fraction must be added. This fraction shows nucleoprotein-like reaction, but it is neither arginine nor nucleic acid. Folic acid is essential for pupation. Attention is drawn to the need for caution in gene-action studies with synthetic media which do not give completely normal development even in the wild type.