bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of the Haemocytes in the Growth and Moulting of An Insect, Rhodnius Prolixus (Hemiptera)
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
Growth and moulting in insects is initiated by a hormone produced in the neurosecretory cells of the brain. This brain factor activates the thoracic (or ‘prothoracic’) glands, which are then believed to secrete the definitive ‘growth and moulting hormone’. These conclusions are based chiefly on experiments with Rhodnius (Wigglesworth, 1940, 1952a), Lepidoptera (Fukuda, 1944; Williams, 1947), Diptera (Possompès, 1953) and Megaloptera (Rahm, 1952), and there is abundant histological and experimental evidence from other groups which points in the same direction (see Wigglesworth, 1954). The possibility remains, however, that there may be yet further links in the chain of endocrine organs, located, for example, in the abdomen. The object of the present work was to investigate this possibility in Rhodnius.
Oxygen Consumption of Castrated Females of the Blow-Fly, Calliphora Erythrocephala Meig
Authors: Thomsen Ellen , Hamburger Kirsten 
Published: April 2021

ABSTRACT
The oxygen uptake of castrated females of Calliphora was measured and found to be of the same order as that of the ‘operated controls i.e. females operated upon in the same way except that their ovaries were not removed. This result confirms the conclusion drawn from previous experiments (Thomsen, 1949), viz. that the influence of the corpus allatum on the oxygen consumption works independently of the presence or absence of the ovaries. However neither in castrated nor in normal females could any correlation be found between the size of the individual corpus allatum and the rate of oxygen consumption of the fly.
The Mechanism of Cell Division in the Cleavage of the Newt’s Egg
Authors: Selman G. G. , Waddington C. H. 
Published: April 2021

ABSTRACT
The early cleavages in eggs of Triturus alpestris have been studied.
Cine-film technique was used to record changes in the shape of the egg and movements of the surface pigment from which measurements of linear and areal changes were made. Local vital staining was also employed. There was no significant net change in the area of pigmented cortex during cleavage.
Before cleavage the egg resembles a viscous liquid drop whose shape is maintained by a uniform elastic shell of Young’s Modulus 1.5 x 105 dynes/cm.2 and thickness about 2μ. The egg assumes a more nearly spherical shape immediately before cleavage when the flexural rigidity of the surface layers increases. The flexural rigidity of the cortical layers was found to be maximal at the beginning of cleavage and minimal midway between cleavages. This variation is similar to that previously recorded for cleavage in sea-urchin eggs by Mitchison & Swann (1955), using a similar method. At any particular stage with respect to the cleavage cycle no variation was found in the rigidity at different points on the egg surface.
Serial sections show cytoplasmic modification below and ahead of the forming furrow. It was concluded that the new unpigmented cortex, by which the daughter blastomeres remain in contact after cleavage, is first formed as a sheet of gel (which in later stages can be seen to be a double layer) which grows downwards by a process involving gelation at its lower edge, through the cytoplasm from the animal toward the vegetal surface. The gel layer is assumed to contract immediately after its formation, and in this way to produce ""dipping in"" of the new furrow and all the observed surface movements. These ideas have been developed to form a detailed theory of cleavage in the newt, and suggest a common basis for the consideration of cell division in echinoderm eggs, plants and other forms, on the basis that the necessary increase in surface area is achieved by the formation of new cortex rather than by the expansion of the original cell membrane.
The Mechanical Properties of the Cell Surface
Authors: Mitchison J. M. , Swann M. M. 
Published: April 2021

ABSTRACTMeasurements with the cell elastimeter on the stiffness of the cell membrane of fertilized sea-urchin eggs show the following general features. There is a sudden rise at fertilization, followed by a fall during the early sperm aster stage to the lowest value reached during development (a Young’s modulus of about 0·58 × 104 dynes/cm.2). The stiffness rises slowly until metaphase, after which it rises rapidly to reach a maximum during late anaphase and early cleavage (6·81 ×104 dynes/cm.2). During the later stages of cleavage the stiffness falls again and reaches a value in the second interphase which is about twice as high as in the first interphase. Measurements on naked eggs in calcium-free sea water indicate that the slow rise in metaphase is due to the development of the hyaline layer. Measurements on swollen and shrunken eggs at cleavage indicate that there is no internal pressure in the eggs at this stage, but similar experiments with eggs at the sperm aster stage yield anomalous results. Observations on the wrinkling point in shrunken eggs show that the maximum possible internal pressure is 19 dynes/cm.2 for sperm aster eggs and 500 dynes/cm.2 for cleaving eggs. The bearing of these results on various theories of the mechanism of cleavage is briefly discussed. The rise in Young’s modulus of the whole cell surface at cleavage argues against theories depending on the action of the spindle and asters, and against theories proposing a contractile ring in the surface. The rise is, however, what might be expected on the basis of the expanding membrane theory.
The Behaviour of the Female Mosquito in Selecting Water for Oviposition
Authors: Anne Hudson B. N. 
Published: April 2021

ABSTRACT
Egg-laying Culex molestus and Aëdes aegypti were able to discriminate between solutions of NaCl ranging from o (distilled water) to 0-136 M. Significantly fewer eggs were laid in solutions above 0-085 M. Similar series of solutions of KC1, MgCl2 and Na2SC4 showed a similar distribution of eggs, but mosquitoes were apparently unable to distinguish between MgSO4 solutions below 0-144 M. Results from all these salts were related to the osmotic pressures produced, but experiments in which isotonic solutions of glucose and NaCl were offered simultaneously showed that osmotic pressure was not a critical factor. Experiments were carried out to locate the sensory areas responsible for discrimination. The possibility that drinking might be associated with the choice of a solution for egg-laying was investigated by removing the proboscis ; operated insects were still able to detect differences in concentration. Covering or removing various regions of the legs revealed that the chemoreceptors concerned were distributed on all the tarsi; indications that they may also be found on the tibiae were obtained.
The Responses of Heteroxenia (Alcyonaria) to Stimulation and to Some Inorganic Ions
Authors: Horridge G. A. 
Published: April 2021

ABSTRACT
The Red Sea Alcyonarian Heteroxema fuscescens (Ehrb.) consists of a pinkish brown fleshy syndete up to 5 cm. in length, firmly attached to a stone or dead coral, from which grows a mass of autozooids with columns 2-4 cm. long and 2-3 mm. in diameter (Fig. 1). The first physiological observations on a xenid were made by Keller (1883) on a brown species from Suez that he considered to be H. fuscescens. He described the rhythmical movements in which the tentacles are clapped together (Fig 2A). The zooids beat independently of one another, and the two halves of a disk, split longitudinally, continued to beat as before but independently. Leaning on the Hertwigs’ (1879) statement that the nervous system of actinians is best developed in the disk, Keller came to the conclusion that there is here a diffusely spread rhythmical centre. He also pointed out the resemblance to the beat of medusae.
A Study of the Oxygen Consumption of Five Species of Leech
Authors: Mann K. H. 
Published: April 2021

ABSTRACT
A correlation between the oxygen consumption of aquatic animals and their ecology has been demonstrated on many occasions (see Prosser, 1950, table 42; Whitney, 1942; Walshe, 1948; and Berg, 1952). Regarding fresh-water forms, two main conclusions emerge: (1) that many inhabitants of rapid streams have a higher rate of oxygen consumption than similar and closely related forms from slow streams or standing water ; and (2) that inhabitants of oxygen-deficient water are often able to maintain a steady rate of oxygen consumption in the face of falling oxygen tension in the medium, until a critical level of oxygen tension is reached, below which the oxygen consumption falls rapidly.
Ionic Regulation in the Ciliate Spirostomum Ambiguum
Authors: Carter L. 
Published: April 2021

ABSTRACT
It is generally accepted that the cytoplasm of fresh-water Protozoa is hypertonic to the medium. This is based on circumstantial evidence and indirect measurements of the osmotic pressure of the body fluids. Inorganic ions are likely to account for a large part of the osmotic pressure, and in certain Protozoa radioactive isotopes may be used to determine the concentrations of ions. The isotope technique has been used to demonstrate that cells in Metazoa, namely nerve, muscle and erythrocytes, accumulate ions and carry out ionic regulation. Evidence is presented in this paper concerning the tonicity of the body fluids of the heterotrichous ciliate Spirostomum ambiguum and concerning its powers of ionic regulation.
Soaring and Gliding Flight of the Black Vulture
Authors: Newman B. G. 
Published: April 2021

ABSTRACT
The soaring and gliding performance of the black vulture has been analysed and the following conclusions are drawn. The wing span of the bird is altered in flight so that it may perform two tasks efficiently. First, that it may soar in rising currents of air for which a low sinking speed and thus a large wing span are required. Secondly, that it may penetrate into wind without undue loss of height for which a reduced wing area is desirable. Adjustment of the wing geometry towards the optimum soaring configuration is achieved by bending forward and opening the primary tip feathers. Since the airflow readily separates from the flat primary feathers at high angle of attack, these feathers, which are emarginated, are parted to form slots. The alula also presumably assists in delaying the flow separation over the primaries. It is unlikely that the opening of the primaries reduces the vortex drag.
The Effect of Vertical Lobe Removal On the Performance of Octopuses in Retention Tests
Authors: Wells M. J. , Wells J. 
Published: April 2021

ABSTRACT
Octopuses were trained to make a tactile discrimination until they attained a criterion of either 75 % or 85% correct responses in twenty successive trials. They were then overtrained for an equal number of trials. Retention of training was tested in twenty unrewarded trials with the same objects 5 or 10 days later. Exactly similar experiments were made with animals trained after removal of the vertical lobes of their brains; these animals were slower to learn, but once trained to a similar standard of accuracy of response they forgot their training at the same rate as controls. This shows that while the presence of the vertical lobe enhances the effect of experience on the establishment of memories causing discrimination of things touched, it does not affect the maintenance of these memories once established.
Temperature Adaptive Behaviour in the Scorpion, Opisthophthalmus Latimanus Koch
Authors: Alexander Anne J. , Ewer D. W. 
Published: April 2021

ABSTRACT
In discussing the possible functions of the pectines of the scorpion, von Ubisch (1922) suggests that they serve ‘um den Stigmen frische Luft zuzufuhren’ by their fanning movements or, alternatively, they prop up the mesosoma so that fresh air can reach the stigmata. Both of these suggestions imply that under conditions of respiratory stress a scorpion will lift its mesosoma clear of the ground so that the book-lungs have free access to air. Although von Ubisch did not apparently observe such behaviour, the recent report of ‘abdominal elevation’ in the Australian scorpion, Urodacus abruptus Poc. (Southcott, 1955) lends colour to such an hypothesis, although work on the functions of the pectines makes it seem very improbable that they actually serve as ‘respiratory fans’. Southcott gives an illustration of a female of U. abruptas in the attitude typical of ‘abdominal elevating behaviour’, and from a comparison of this with some of the stances observed in various South African scorpions it becomes clear that such behaviour occurs also in the latter. Opisthophthalmus latimanus Koch, O. nitidiceps Poc., O. austeras Karsch., Parabuthus planicauda Poc. and Uroplectes triangulifer Thor, all show the pattern to varying extents, and it was felt that with so many species available for study, it would be profitable to follow up Southcott’s observations. Preliminary tests indicated that the biological significance of this phenomenon appeared to be the same in all these species, and the results described below refer particularly to Opisthophthalmus latimanus which has been most intensively studied.
The Relation of Oxygen Consumption to Body Size and to Temperature in the Larvae of Chironomus Riparius Meigen
Authors: Edwards R. W. 
Published: April 2021

ABSTRACT
The oxygen consumption rates of 3rd- and 4th-instar larvae of Chironomus riparius have been measured at 10 and 20° C. using a constant-volume respirometer. The oxygen consumption is approximately proportional to the 0·7 power of the dry weight : it is not proportional to the estimated surface area. This relationship between oxygen consumption and dry weight is the same at 10 and at 20° C. The rate of oxygen consumption at 20° C. is greater than at 10° C. by a factor of 2·6. During growth the percentage of dry matter of 4th-instar larvae increases from 10 to 16 and the specific gravity from 1·030 to 1043. The change in the dry weight/wet weight ratio during the 4th larval instar supports the theory of heterauxesis. At 20° C., ‘summer’ larvae respire faster than ‘winter’ larvae.
A Quantitative Description of Protoplasmic Movement During Cleavage in the Sea-Urchin Egg
Authors: Hiramoto Y. 
Published: April 2021

ABSTRACT
Quantitative information on the protoplasmic movement during cleavage is one of the most important desiderata in the study of cell division. Spek (1918) described the protoplasmic streaming during cleavage and emphasized the importance of the surface tension in the cell division, giving attention to the similarity of this protoplasmic streaming to the streaming within an oil drop dividing as a result of local difference in surface tension. Dan and his collaborators (Dan, Yanagita & Sugiyama, 1937; Dan, Dan & Yanagita, 1938; Dan & Dan, 1940, 1942, 1947; Dan, 1943; Dan & Ono, 1954; Ishizaka, 1958) reported a series of experiments in which the cortical movement during cleavage was followed by measuring the movement of kaolin particles adhering to the cell surface. The results obtained by Spek and by Dan provide qualitative information on the protoplasmic movements during cleavage. However, from their data it is neither possible to make a quantitative analysis of the protoplasmic movement nor to infer the correlation between cortical and endoplasmic movements in detail. In the present work protoplasmic (both cortical and endoplasmic) movement during cleavage of the sea-urchin egg is described in a quantitative fashion, in order to provide basic data for the study of cell division.
Acoustic Reflexion Experiments with Perch (Perca Fluviatilis Linn.) to Determine the Proportion of the Echo Returned by the Swimbladder
Authors: Jones F. R. Harden , Pearce G. 
Published: April 2021

ABSTRACT
Measurements were made under controlled conditions to determine the contribution of the swimbladder to the reflexion of acoustic energy from the perch, Perca fluviatilis. The amplitude of the echo fell by 50% when the swimbladder was emptied; this was observed both when the dorsal surface and when the lateral surface faced the direction of the incident sound energy. The polar diagram of the fish with its natural swimbladder is similar in shape to that obtained with a false ‘Onazote’ swimbladder.
The Physical Properties of the Swimbladders of Fish Other Than Cypriniformes
Authors: Alexander R. McN. 
Published: April 2021

ABSTRACT
No excess internal pressure, such as has been found in the Cypriniformes, could be detected in the swimbladders of seventeen species from other orders. The swimbladder wall in these fish exercises no appreciable constraint on chnges of buoyancy with depth. Determinations of sinking factor and swimbladder volume are reported.
Interaction Between Walking and Probing in Aphis Fabae Scop
Authors: Ibbotson A. , Kennedy J. S. 
Published: April 2021

ABSTRACT
In experiments with apterous adult aphids walking on non-plant surfaces, rostrum protraction and probing of the surface were elicited by a variety of situations having the common effect of interfering mechanically with the normal pattern of locomotory movements. A uniform wax ridge which fitted the span of the aphid’s legs but afforded a poor grip to the tarsi and broke up the stepping rhythm, combined with an over head light, generated a cyclical alternation between walking and probing. When the uniform substrate was interrupted by some form of obstacle to locomotion further probes were elicited, and the more abruptly and completely locomotion was arrested, the more promptly these appeared. Visual stimulation (from black models of aphid size) and olfactory stimulation (from the aphids’ siphuncle wax) also caused walking aphids to stop and probe. Readiness to probe varied greatly with age and pretreatment. Aphids denied access to a host plant for 1-2 days probed more frequently at random in response to the substrate but less frequently at objects encountered. Walking and probing interact in the manner of antagonistic reflex systems, and the diverse types of stimulus which elicited probing may all have done so indirectly by first inhibiting locomotion.
Loss of Water by Excretion and Defaecation in the Tsetse Fly
Authors: Bursell E. 
Published: April 2021

ABSTRACT
The water content of the blood meal of tsetse flies is reduced from 79 to about 55% within the first 3 hr. after feeding. The water which is abstracted from the gut contents serves to bring the tissues of the fly to full hydration, and any excess is excreted. The degree of dehydration of the gut content depends on the amount of blood taken, relatively more water being retained in partial feeds. The water content of faecal matter is about 75% in flies maintained at high relative humidity throughout the hunger cycle, only 35% in flies maintained in dry air. The difference reflects a saving of more than 30% of the total water reserves of the fly under conditions of desiccation.
The Source of Carbon Monoxide in the Float of the Portuguese Man-of-War, Physalia Physalis L
Authors: Wittenberg Jonathan B. 
Published: April 2021

ABSTRACT
Carbon monoxide, 0.5-13 %, is found in the float gases of Physalia. Oxygen comprises 15-20 % of the total gas. Carbon dioxide is present in negligible amounts. The gas gland, pneumadena, is the site of carbon monoxide formation. L-Serine is the substrate for carbon monoxide formation. A strikingly large concentration of folic acid is found in the gas gland. It is suggested that carbon monoxide secretion serves to inflate the float of Physalia and that carbon monoxide is later slowly replaced by air through diffusion and exchange.
Inhibition and Rhythmic Activity of the Circular Muscles of Calliactis Parasitica (Couch)
Authors: Ewer D. W. 
Published: April 2021

ABSTRACT
The responses to electrical stimulation of isolated rings of the column and pedal disk of Calliactis are described. Such rings make slow spontaneous contractions which are frequently rhythmical, the interval between contractions normally being 7-20 min. Continuous low-frequency stimulation inhibits spontaneous activity of rings from the pedal disk and also of fresh rings from more adoral regions of the column. Older rings from the mid-column respond to such stimulation by a tetanic contraction. The latency of response to electrical stimulation of pedal rings is of the order of 120 sec. This latency is not affected by stimulation frequency but is prolonged by increase in the number of shocks applied. Stimulation of a pedal ring at the onset of a contraction prevents the further development of this contraction, while stimulation as a contraction reaches its maximum is followed by more rapid relaxation than in unstimulated controls. Mid-column rings when freshly prepared show a latency of the order of 120 sec. As the preparation ages, a double response to stimulation appears ; the first response has a latency of about 30-40 sec. and presently becomes the only type of response shown. If two sets of stimuli are applied to a mid-column ring, the magnitude of response to the second set increases as the time between stimulations increases. With long intervals an almost total contraction is obtained in response to a single shock. The effect of intercalated stimuli upon the rhythm of spontaneous activity is studied. The effect is very variable and it is suggested that this is the result of electrical stimulation having both an excitatory and an inhibitory effect. The very long latent periods characteristic of pedal rings and the rhythmic activity of these preparations are interpreted as interactions of excitation and inhibition.
Transmission Through the Last Abdominal Ganglion of the Dragonfly Nymph, Anax Imperator
Authors: Fielden Ann 
Published: April 2021

ABSTRACT
In the last abdominal ganglion of the dragonfly nymph afferent fibres from tactile endings on the paraprocts synapse with large ascending fibres in the ventral nerve cord. The latter run the length of the cord and synapse with efferent fibres in the segmental nerves of the thoracic and abdominal ganglia. The evasion response is mediated by this pathway and can be elicited by electrical stimulation of the nerves from the paraprocts. The synapses between tactile afferents and ascending fibres show delays of 2.0-4.5 msec, and transmit synchronously to frequencies of 50-60/sec. There is no evidence for facilitation at these synapses, but facilitation and/or temporal summation is of importance at the efferent synapses which appear more labile in their properties. Stimulation of the paraproct nerves shows the existence of a reflex connexion between afferents and efferents of the same nerve comparable to that of the vertebrate spinal cord. This provides a preparation for a study of the relationship between sensory and motor neurons in the insect nervous system. Transmission through the last abdominal ganglion and cord is compared with that in the cockroach and locust.
The Landing Responses of Insects
Authors: Goodman Lesley J. 
Published: April 2021

ABSTRACT
Although insect flight, and the stimuli which induce it, have been studied extensively, the way in which insects land has received little attention. The majority of insects fly with the pro- and meso- and in some cases the metathoracic legs folded up beneath the body and the legs must be lowered before the insect makes contact with the landing surface. This paper describes a detailed examination of the movements of the legs of the fly Lucilia sericata and other insects and an attempt to determine the stimuli which result in Lucilia lowering its legs on approaching a suitable landing surface. There are several possible stimuli which may cause the legs to be lowered ; the object which the fly is approaching will appear to increase in size and this stimulus will of necessity be accompanied by a change in the light intensity falling on certain of the ommatidia. If the insect has a reasonable field of binocular vision, the lowering of the legs may be based upon an appreciation of its distance from the landing surface, together with its rate of approach to that surface. Alternatively, it may always lower the legs when the image of the approaching object falls simultaneously on corresponding ommatidia of the two eyes.