bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxygen Consumption and Cell Size. A Comparison of the Rate of Oxygen Consumption of Diploid and Triploid Prepupae ofDrosophila MelanogasterMeigen
Authors: Ellenby C. 
Published: April 2021

ABSTRACTThe oxygen consumption and surface area of individual diploid and triploid prepupae of Drosophila melanogaster have been measured, the cells of triploid animals being larger. The mean weights for the types examined are different but their ranges overlap almost completely. By covariance analysis it is shown that, after adjustment for difference in body size, there are no differences in the rates of oxygen consumption. It is concluded that, for these animals, cell size has no influence on the rate of oxygen consumption. The relationships between body weight, surface area, and oxygen consumption have been further investigated. It is shown that, despite the greater inaccuracy of the method by which surface area is determined, oxygen consumption can be predicted more accurately from surface area than from body weight. The results are discussed in relation to an earlier investigation of the oxygen consumption of other genotypes (Ellenby, 1945 a, b). Possible technical causes of certain differences between the two series of results in the relationship of oxygen consumption and body weight are explored ; it is concluded, however, that they are almost certainly due to differences, not necessarily genetical, between the animals used in the two series.
Metabolism of the Black Snake Embryo
Authors: Clark Hugh 
Published: April 2021

ABSTRACT
Bohr (1904) reported CO2 production of an embryo of Natrix natrix, weighing 0·46 g., to be 120 mm.3/g./hr. at 14·2° C.; the CO2 produced at 28° C. was 3 times that at 15° C., and production by a newly hatched snake at 15° C. was approximately 90 mm.3/g./hr. Other data are given, but they are not related to stage of development, and oxygen utilization was not measured. Zarrow & Pomerat (1937) made rather exhaustive studies of the effect of temperature on various aspects of respiratory behaviour of the smooth green snake during the last week of development. It appeared profitable, therefore, to obtain details of respiratory exchange throughout the developmental period of snake embryos. Such data were available from the same embryos which served for the excretion studies reported elsewhere in this Journal by the author (1953).
Cleavage of Sea-Urchin Eggs in Colchicine
Authors: Swann M. M. , Mitchison J. M. 
Published: April 2021

ABSTRACT
Sea-urchin eggs have been treated with strong colchicine during mitosis, and examined with a variety of techniques. Polarized light observations show that cleavage can take place when the asters and spindle have completely disappeared, provided the cell has reached mid-anaphase, by which time the chromosome groups are well separated. Observations on stained sections have confirmed those with polarized light and have also shown that the minimum separation of the chromosome groups for successful cleavage is about 5 μ. Viscosity measurements have shown that colchicine destroys the gelated structure of the asters, and reduces the viscosity of the cleaving egg to about the same low value as the unfertilized egg. Cycles of chromosome condensation persist in eggs treated with weak colchicine, even though cleavage has been prevented by an early application of the colchicine. These cycles are associated with changes in the rigidity and light-scattering properties of the cortex. The relevance of these observations to some theories of cell division is discussed.
Microdissection Experiments on Sea-Urchin Eggs At Cleavage
Authors: Mitchison J. M. 
Published: April 2021

ABSTRACT
Chambers (1938) described an experiment in which he cut open one blasto-mere of a cleaving sea-urchin egg at the dumb-bell stage in isotonic KCl. The other blastomere contracted like a ‘deflating balloon’, and this has been taken by other workers as evidence of a positive membrane tension in the cleaving egg. This experiment has been repeated with other sea urchins in various media. It is concluded that this effect only takes place in one species of sea urchin, in an abnormal medium, and after it has suffered irreparable damage. It is not, therefore, legitimate to suppose that there is normally a positive membrane tension in a cleaving egg. It is found that eggs will continue to cleave with one blastomere in an irregular shape which indicates that, on the contrary, there is no membrane tension and no internal pressure. These are the conditions demanded by the ‘expanding membrane’ theory of cleavage. It is found that the furrow of a cleaving egg will pass through a needle placed in its path. This result argues against a simple contracting ring in the furrow region being responsible for cleavage. Chambers (1938) found that an egg will continue to cleave when its asters have been destroyed by stirring. This result has been confirmed by a similar experiment on a different species of sea urchin. This is crucial evidence against an astral mechanism of cleavage. The effects of compressing cleaving eggs have been studied. It is found that compressed eggs continue to cleave unless the degree of flattening is considerable; that cleavage is delayed before it is finally stopped; and that eggs in Ca-free sea water are more susceptible to compression than eggs in ordinary sea water. These results are consistent with the ‘expanding membrane’ theory.
The Moulting Fluid of the Cecropia Silkworm
Authors: Passonneau Janet Vivian , Williams Carroll M. 
Published: April 2021

ABSTRACTThe initiation of adult development in the pupa of the Cecropia silkworm is accompanied by a retraction of the hypodermis from the pupal cuticle; the exuvial space is simultaneously flooded with the moulting fluid. During the first two-thirds of adult development the moulting fluid is a dilute, aqueous, proteinaceous gel resembling egg albumen ; at this time it is without effects on the pupal cuticle. On approximately the fourteenth day of adult development the gel is converted into a sol and shows a considerable increase in chitinase activity and the first demonstrable proteolytic activity. The late, active moulting fluid then begins to hydrolyse the protein and chitin in the overlying pupal endocuticle. By the twentieth day the old endocuticle has disappeared. The tanned proteinchitin complex of the sclerotized exocuticle is not attacked. Finally, the moulting fluid is completely resorbed into the underlying insect. The residual pupal exocuticle forms the bulk of the exuviae. Moulting fluid and blood are compared in respect to the following properties : consistency, cellular content, solubility, refractive index, water content, chemical composition, total nitrogen, protein nitrogen, pH, redox potential, and enzymatic content. The moulting fluid shows numerous quantitative and qualitative differences from the blood. The fluid is, evidently, a distinctive secretory product of the underlying integument—presumably of the hypodermis itself. A dynamic state exists between the moulting fluid and the underlying insect. Radioactive glycine, injected into the moulting fluid, was promptly resorbed and incorporated into the protein of the adult moth. Several lines of evidence suggest that the secretion or activation of the moulting fluid enzymes are synchronized with the sclerotization of the underlying new cuticle. This synchronization, it is suggested, may serve to protect the new cuticle from the hydrolytic action of the moulting fluid.
The Forces Exerted by the Tube Feet of the Starfish During Locomotion
Authors: Kerkut G. A. 
Published: April 2021

ABSTRACTDoubt has existed as to whether the tube feet of a starfish in locomotion act as a system of levers or whether they form a traction system, attaching to the substratum and contracting so as to pull the animal along. This problem has been investigated by recording the forces exerted by a single tube foot. The recording apparatus is described. It is shown that both lever and traction methods can be used according to circumstances. When the starfish is walking on a horizontal surface it is shown that the tube feet certainly act as struts and that they probably also act as levers. When the starfish is climbing upon a vertical surface (or meeting with resistance upon a horizontal surface) the tube feet attach themselves to the substratum and form a traction system.
Laboratory Experiments on Gregariousness During Setting in Balanus Balanoides and Other Barnacles
Authors: Knight-Jones E. W. 
Published: April 2021

ABSTRACT
Laboratory experiments showed that cyprids of Balanus balanoides settled readily only when offered surfaces which bore settled barnacles of their own species, or the cemented bases left on surfaces from which these barnacles had been removed. Without such surfaces they proved to be capable of postponing setting for at least 2 weeks, and they chose such surfaces in preference to similar surfaces which bore related species. Cyprids of B. crenatus and Elminius modestus were also capable of making this choice.
Setting usually occurred in the immediate vicinity of barnacles or bases, but some cyprids crawled short distances away during their final reconnaissances. When they encountered barnacles attached to glass, they were stimulated to proceed with setting, but they swam away from this unfavourably smooth surface and settled on bare stones nearby.
Fragments from various parts of the body, placed upon surfaces which had never borne barnacles, made these somewhat more favourable for setting. Since attached bases alone produced a strong reaction, the cyprids probably respond to contact between their groping antennules and some substance in the cuticle. They did not settle readily when prevented from making contact with adults by a barrier of bolting silk, or with bases by a thin film of nitrocellulose ; chemosensory perception of a water-soluble substance, emanating from settled barnacles, is therefore unlikely to be involved.
The power of the bases to induce setting was retained after heating to over 200° C., but not after heating to 275° C., when charring occurred. It withstood prolonged washing in water, heating with fat solvents and dilute acids, and treatment in the cold with caustic alkalis, concentrated acids, pepsin, formaldehyde, benzoquinone, sodium sulphide, phenol, urea, and diazonium solution. It was destroyed in the cold by sodium hypochlorite, which was observed to dissolve the bases, and also by hot concentrated acids and alkalis. The chemical properties of the active substance are thus entirely consistent with those of quinone-tanned proteins, which are known to form the epicuticle and attachment cement.
A field experiment showed that similar behaviour occurs under natural conditions. It leads cyprids to suitable habitats and it facilitates breeding.
An Organ for Proprioception and Vibration Sense in Carcinus Maenas
Authors: Burke W. 
Published: April 2021

ABSTRACT
Little is known about the mechanism of proprioception in arthropods. A number of organs or groups of cells have been described which on anatomical grounds might serve proprioceptive function, e.g. the ‘chordotonal organs’ in insects (Graber, 1882) and crustaceans (Wetzel, 1933), bipolar cells in insect muscle (Hilton, 1924; Rogosina, 1928) or in crustacean joints (Tonner, 1933), the ‘myochordotonal’ organ in the meropodite of decapod crustaceans (Barth, 1934), the ‘muscle receptor organ’ and ‘A-cells’ of various crustaceans (Alexandrowicz, 1951,1952 a, b). Physiological evidence has been obtained for the crustacean ‘muscle receptor organ’ by Wiersma, Furshpan’ Florey (1953), who showed that it gives rise to a discharge of afferent impulses during stretch, as was suggested by Alexandrowicz. The existence of kinaesthetic organs in the walking limbs of crustaceans was indicated by the fact that movements of the joints can elicit impulses in the limb nerves (Barnes, 1930, 1931) and in the central nervous system (Prosser, 1935). In insects there is evidence for a proprioceptive discharge from the campaniform sensilla (Pringle, 1938a, b, 1940) and the hair sensilla at the joints (Pringle, 1938c).
Internal Hydrostatic Pressure of the Fundulus Egg
Authors: Kao Chien-Yuan , Chambers Robert 
Published: April 2021

ABSTRACT
By means of a mercury manometer connected to a micropipette, the internal hydrostatic pressure of the unfertilized Fundulus egg was measured. Upon activation of the egg by micropuncture when the platelets in the cortex of the egg proper disappeared, there was a progressively increasing internal pressure which finally stabilized at 150 mm. Hg. The pressure was accompanied by the formation of a perivitelline space which contained a clear, colloidal material. The measured internal hydrostatic pressure of the egg was diminished by any means which decreased the perivitelline space. It was concluded that the perivitelline substance is the chief factor contributing to the pressure. The changes in volume of the egg proper are inversely proportional to the size of the perivitelline space, indicating that the surface of the egg proper is permeable to water.
The Passage of Starch Through the Stomach of the Sheep
Authors: Weller R. A. , Gray F. V. 
Published: April 2021

ABSTRACT
Micro-organisms are now known to be the agents responsible for many important chemical changes in the rumen contents. By the fermentation of polysaccharides they produce large quantities of the lower fatty acids which are absorbed and utilized by the host; they digest a considerable part of the protein in the fodder and resynthesize proteins during their own growth and proliferation; they are capable of converting suitable forms of non-protein nitrogen to protein, and can synthesize many of the vitamins. The accurate assessment of the extent to which such processes take place, however, presents major difficulties—difficulties bound up with the fact that the rumen is a reservoir into which more or less continuous supplies of food, water and saliva enter, and from which some products of the fermentation are absorbed, while others, together with food residues, pass to lower levels of the alimentary tract. As a consequence, the extent to which various compounds are digested, released or synthesized, cannot be determined from the concentrations of these substances in the rumen, and so indirect methods of investigation must usually be applied to such problems.
Changes in the Blood Potassium Concentration of the African Migratory Locust (Locusta Migratoria Migratorioides R. & F.) During Food Deprivation, and the Effect on Neuromuscular Activity
Authors: Hoyle G. 
Published: April 2021

ABSTRACT
The concentrations of sodium and potassium in the haemolymph of the locust Locusta migratoria migratorioides R. & F. have been determined by flame photometry. The molar ratio of sodium to potassium is normally about 5:1. During a short period of starvation the potassium content of the haemolymph decreases by as much as 50 %. The change in potassium is adequate to account for observed differences in muscle membrane resting potentials and for variations in the mechanical responses of the muscles to nerve stimulation. The ability of 5th-instar hoppers to respond to stimulation by hopping or jumping is increased after a short period of starvation owing to the increased mechanical responses of the muscles. It is suggested that changes in diet potassium will be found to influence behaviour of locusts by the direct effect of the potassium on muscle fibre activity.
Slow and Fast Responses in Cockroach Leg Muscle
Authors: Wilson V. J. 
Published: April 2021

ABSTRACT
Intracellular recording from individual muscle fibres of the flexor tibiae of the cockroach shows two types of action potentials. One of these represents fast fibre activity, while the other represents slow fibre activity in this muscle. The fast response consists of an all-or-none potential varying from 40 to 85 mV., with 60% of the responses between 55 and 70 mV. This potential has an overshoot over the resting potential, and is followed by an absolute and a relative refractory period. For these reasons it is considered likely that the potential is a propagated one. The slow response is a small, facilitating potential, varying from 8 to 20 mV., and is quite likely a local phenomenon. All the evidence indicates that the two types of activity do not take place in the same muscle fibres, but rather represent the responses of two different types of fibres, as is the case in some amphibian muscles. Gradation of activity in the fast system seems to depend solely on the activation of a very small number of motor units and on mechanical summation. The response of this system shows little, if any, facilitation as the frequency of stimulation is increased. The facilitating slow system may be concerned with slower, more finely graded movements. The resting potential in roach muscle has an amplitude of 45 ± 9 mV., which falls within the range expected on the basis of the intracellular and extracellular potassium concentrations. Slow and fast fibre activity in insects and Crustacea is discussed, and a revision of the earlier work on Crustacea with the use of intracellular recording is suggested.
Studies on the Transport of Neurosecretory Material in Calliphora Erythrocephala by Means of Ligaturing Experiments
Authors: Thomsen Ellen 
Published: April 2021

ABSTRACT
Ligation of the cardiac-recurrent nerve in adult females of Calliphora resulted in an accumulation of secretory material in the proximal part of the nerve. The secretory material was demonstrated partly in stained sections, partly in living nerves by means of darkfield illumination.
By the latter method moniliform bluish white nerve fibres could be seen in the living normal (i.e. unligated) cardiac-recurrent nerve. In all probability this appearance of the nerve fibres is due to their content of neurosecretory material. Some axons of the nervi oesophagei and the nervi corporis allati had a similar appearance. No such fibres could be observed in the living abdominal nerve, and ligation of this nerve did not result in an accumulation of secretory material.
The Orientation of Ants
Authors: Vowles D. M. 
Published: April 2021

ABSTRACT
Von Frisch has shown that in the honey-bee orientation established in relation to one directional stimulus (light) can be transferred to another directional stimulus (gravity or polarized light). In the present work the orientation of ants has been studied in experiments in which one type of directional stimulus has been replaced by another. Light, gravity and polarized light have been used as stimuli. When light and gravity are interchanged, the ant’s successive orientations to the two stimuli are correlated. The angle between the track and the stimulus is the same for both orientations. When light and polarized light are interchanged, the ant’s successive orientations are again correlated. The actual relationship depends on the experimental conditions. When polarized light and gravity are interchanged there is no significant correlation between successive orientations. It is suggested that in bees and ants there is a single taxis mechanism for orientation to light, polarized light and gravity, and that the ‘setting’ of this mechanism during an orientation to one stimulus persists and partially determines the subsequent orientation to another stimulus.
The Orientation of Ants
Authors: Vowles D. M. 
Published: April 2021

ABSTRACT
The orientation of ants to gravity has been investigated, and it is shown that orientations symmetrically placed on either side of the vertical are confused. The georeceptor is located in the antenna, and is probably Johnston’s organ. Only one antenna is in use at any one time during geo-orientation. The light compass reaction has been investigated and it is shown that orientations θ° and 180–θ° are confused. No explanation can be offered for this. The results are discussed in relation to the hypothesis that ants have a taxis mechanism common to all senses. It is suggested that the function of this mechanism is to set up a temporary labile symmetry of the ant with respect to orientatory stimuli.
The Inorganic Composition of the Blood of Mytilus Edulis and Anodonta Cygnea
Authors: Potts W. T. W. 
Published: April 2021

ABSTRACT
Analyses have been made of the inorganic constituents of the blood of Mytilus edulis and Anodonta cygnea. Mytilus blood resembles sea water in total concentration and composition, but has greater concentrations of calcium, potassium and total carbon dioxide. Anodonta blood has a very low total concentration of solutes, but the concentrations of calcium and carbon dioxide are of the same order of magnitude as the concentrations in Mytilus blood. This is discussed with reference to solubility of calcium carbonate in ionic solutions, and it is concluded that the blood of both animals is saturated with respect to aragonite.
The Exchange of Labelled Sodium in the Larva of Aedes Aegypti L.
Authors: Treherne John E. 
Published: April 2021

ABSTRACT
The exchange of labelled sodium between the external medium and the haemolymph and whole body has been investigated in the larva of Aedes aegypti. The time for half exchange was of the order of 62 hr. It was found that most of the exchange of labelled sodium occurred through the anal papillae, although smaller amounts enter the haemolymph through the gut and general body surface. Transfer constants have been used to describe the resultant turnover of labelled sodium in the whole system. The rate of uptake of sodium was independent of the external concentrations used in these experiments. Potassium ions do not compete with sodium for uptake, which suggests that separate mechanisms are responsible for the accumulation of these two ions. Larvae were able to retain the sodium in the haemolymph, with relatively little loss, in glass-distilled water. The effect of temperature on the rate of uptake of labelled sodium has been investigated.
The Chemical Composition of the Blood of Some Aquatic Chordates, Including Members of the Tunicata, Cyclostomata and Osteichthyes
Authors: Robertson James D. 
Published: April 2021

ABSTRACT
Included in the Chordata are groups of widely different organization which have certain common morphological features at some stage of their existence, a notochord, a hollow dorsal nerve-cord, and gill-pouches or gill-clefts. The various subphyla differ in most other morphological characters, and in their physiology, especially in methods of respiration, feeding, digestion, excretion, reproduction, and locomotion. A study of the composition of the blood in members of the aquatic Chordata shows that variations exist in the equilibrium between the internal and external media which seem to be conditioned by the level of organization of different groups. Most of the data on these animals, however, is incomplete, and rather unsatisfactory on grounds which are discussed below in each section.