bluuebunny/crossref_metadata_2025 huggingface dataset:
The Forces Exerted by the Tube Feet of the Starfish During Locomotion
Authors: Kerkut G. A.
Published: April 2021

Doubt 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

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

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

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

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

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

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

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

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

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

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

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

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.
Ionic Regulation in the Palaemonid Prawn Palaemon (=Leander) Serratus
Authors: Parry G.
Published: April 2021

Analyses have been made of the blood and urine of Palaemon serralus for the inorganic ions Na, K, Ca, Mg, Cl, SO4, the animals being kept in 50, 100 and 120 % sea water. When the animal is in 100 % sea water the concentrations of ions in the blood, expressed as percentages of their concentrations in the medium (to the nearest 5 %) are as follows: Na, K and Cl, 85%; Ca, 105%; Mg, 20%; SO4, 10%. When the animal is in 50% sea water the corresponding figures are: Na and Cl, 105%; K, 120%; Ca, 200%; Mg, 20%; SO4, 10%. When the animal is in 120% sea water the corresponding figures are: Na, K and Cl, 85 % ; Ca, 115%; Mg, 30 % ; SO4, 20 %. The concentrations of Na, K and Ca in the urine are always slightly ( 20 %) less than their concentrations in the blood. The concentration of Cl is slightly greater in the urine than in the blood (10-20 %) and the concentrations of Mg and SO4 are very much greater, by factors of up to 7 times. The relative concentrations of ions in blood and urine do not change substantially with changes in the external medium. The antennal gland, although it plays no part in purely osmotic regulation, is no doubt partly responsible for maintaining the low blood concentrations of Mg and SO4.
Observations On the Respiratory Physiology and On the Haemoglobin of the Polychaete Genus Nephthys, With Special Reference to N. Hombergii (Aud. Et M.-Edw.)
Authors: Jones J. D.
Published: April 2021

Littoral representatives of the genus Nephthys are described as burrowing forms, able to irrigate their burrows with well-aerated sea water except when the sand is exposed by the tide. Then they are sealed in and have no access to oxygen outside the sand. The concentration of dissolved oxygen in the sand water corresponds to a tension of about 7 mm. of Hg compared with a value about twice as great in the residual water in Arenicola burrows. Extracellular pigments in the blood and coelomic fluid of Nephthys spp. are characterized as haemoglobins. The quantity of these pigments is shown to be inadequate as an oxygen store for the exposure period. Dissociation curves for both pigments from N. hombergü are found to be approximately hyperbolic and the oxygen affinities relatively low. The significance of the difference in oxygen affinity and the direction of the Bohr effect, between the vascular and coelomic pigments cannot yet be evaluated. It is suggested that the Nephthys pigments are unspecialized and may function as a high-tension oxygen transport system only when the sand is covered by the sea. This is contrasted with the possibility of low-tension oxygen transport by the haemoglobin of Arenicola.
Some Temperature Responses of Nymphs of Locusta Migratoria Migratorioides (R. & F.), With Special Reference to Aggregation
Authors: Chapman R. F.
Published: April 2021

The results of experiments in a temperature gradient showed a definite temperature ‘preference’ on the part of hoppers (nymphs) of all stages. This ‘preference ‘was constant from instar to instar but varied with the preconditioning temperature. The rate of movement of first-instar hoppers was shown to increase in a linear manner with temperature up to 25°C., above which the rate fell off. It is suggested that these are quantitative data supporting Kennedy’s (1939) remarks on negative thermokinesis. Experiments in 12 1. cages showed that group formation depends on a patchy temperature field rather than on any particular temperature, and that environmental conditions are more important than mutual responses of the hoppers. Hoppers less than 3 days old, as well as older ones, formed groups under the conditions of patchy temperature. The experiments suggested that surface temperatures are more important than air or body temperatures in the initial formation of groups. Basking groups induced by local radiant heat in a large cage did not differ in form from the groups in the 12 1. cages formed in the absence of radiant heat. Surface texture was shown to be unimportant in group formation, hoppers always collecting on the hotter surface even when temperature differences were of the order of only 1° C. The groups were shown to be in a very dynamic state, with hoppers continually coming and going. The average time spent in a group by any one hopper was 6 min. 46 sec. Formation of basking groups in the field depends on the physiological state of the hoppers, rather than on any definite temperature.
Homing Orientation in Pigeons in Relation to Opportunity to Observe the Sun Before Release*
Authors: Pratt J. G. , Thouless R. H.
Published: April 2021

A total of ninety-six single releases of pigeons was made over distances varying from 48 to 238 miles. The birds were transported under cover which prevented them from seeing the landscape or the sun. It was generally their first release from a point out of sight of the loft. The vanishing points (as observed through field-glasses) from all releases combined showed a significant tendency to be in the homeward half of the circle. The direction of the bird from the release point was observed at various intervals of time from 10 sec after release. There was a statistically significant relationship between the direction at 10 sec and that at 40 sec (or 60 sec.), and the latter directions were closely related to those of disappearance. To test the hypothesis that correct orientation depends on an interval of time for observing the sun’s motion, some birds were allowed to see the sun for some time before flight, while others were kept in shadow. Even after the short interval of 10 sec., the no-sun birds showed no less accuracy of orientation than did the sun birds. In two releases the pigeons showed a consistent choice of direction not within the home half of the circle. This suggests the need for caution in drawing conclusions based on few release points, and the desirability of using many release points and taking the average orientation at each as the statistical unit. Our results strongly suggest that there is no difference between the orientation of pigeons that have and pigeons that have not seen the sun before release. This conclusion is, however, tentative until it is confirmed by further experiments using a larger number of release points.
The Behaviour of Anodonta Cygnea L., and Its Neurophysiological Basis
Authors: Barnes Gordon E.
Published: April 2021

Anodonta cygnea L. in captivity exhibits rhythmical behaviour as follows: Periods of activity and quiescence alternate, with frequencies varying with different specimens from 3 to 30 per week. During the periods of quiescence the shell valves are completely adducted. During active periods the valves normally gape. (The ‘slow’ rhythm.) During the active periods the adductor muscles show frequent rapid contractions followed by slow relaxations. This activity is also rhythmical, and has a frequency of up to 20 per hour. (The ‘rapid’ rhythm.) The neuromuscular mechanism of these rhythms has been investigated, and it is shown that : (a) both adductor muscles participate in the rhythms ; (a) the slow rhythm is a function of the unstriated portions of the muscles ; (c) the rapid rhythm is a function of the striated portions of the muscles ; (d) the rapid rhythm in each adductor muscle is controlled by its nearest ganglia; (e) the slow rhythm in each adductor muscle is controlled by the combined effect of the nearest ganglia, which tend always to produce a tonus, and the cerebropleural ganglia, which at intervals inhibit that tonus; (f) the control of the rhythms appears to be intrinsic in the nerve ganglia, and independent of peripheral stimulation. The effect of morphine hydrochloride on Anodonta has been investigated, and it is shown that, in addition to a possible narcotic effect, it abolishes the tonus of the unstriated portions of the adductor muscles. A reflex is described which leads to the relaxation of the tonus in the adductor muscles, and the commencement of a new period of activity. The stimulus is vibration and/or rotation. On the basis of the above conclusions regarding Anodonta a hypothesis is put forward to account for certain facts about the contraction and relaxation of the adductor muscles of Mytilus.
The Excretion of Sodium, Potassium and Water by the Malpighian Tubules of the Stick Insect, Dixippus Morosus (Orthoptera, Phasmidae)
Authors: Ramsay J. A.
Published: April 2021

The excretion of sodium, potassium and water by the Malpighian tubules of the stick insect has been further studied in preparations of single tubules isolated in droplets of medium under liquid paraffin. There is some gradation of physiological activity along the length of the superior tubule. Sodium, potassium and water are secreted into the tubule at all levels, but the sodium/potassium ratio is greater in the proximal region. The proximal and middle regions of the inferior tubule have not been shown to differ in any way from the corresponding regions of the superior tubule. The distal dilatation has quite different properties and does not produce urine. The rate of urine flow increases markedly as the potassium concentration in the medium is increased; the corresponding effect of sodium is barely detectable. Sodium, like potassium, can be actively transported against an electrochemical gradient, and does not appear to compete with potassium in the secretory mechanism. The rates of secretion of sodium and potassium vary in direct proportion to the respective concentrations of these ions in the medium. The rate of secretion of potassium is more than ten times greater than that of sodium.
An Investigation of Homing Ability in Pigeons Without Previous Homing Experience
Authors: Pratt J. G.
Published: April 2021

Three different groups of pigeons were given homing releases, the first at 143 miles and the other two at 75 miles. Approximately half of the birds (untrained group) had made no homing flight before they were released in the long-distance test. The others (trained group) had been released 3 times in different directions at 10 miles from the loft in one experiment and at 2 – 3 miles in the other two. Both the trained and untrained birds showed a statistically significant tendency to vanish from sight at the release point in the homeward half of the circle, which confirms Matthews’s results with untrained pigeons. There was no appreciable difference in homing success and speed between these two groups. More than 50 % of each group homed, while Matthews had only one out of thirty-nine untrained birds return to the loft. The untrained birds were released ahead of the trained birds in each experiment. In the third experiment, two untrained birds homed, separately, without being overtaken by any trained birds. Thus these two birds showed clearly that pigeons without previous homing experience could and would complete a longdistance flight to the loft unassisted. Subsequent tests in which only untrained birds were released have confirmed this finding. Birds differing in both age and stock were compared in the second and third experiments. Within the range of 4 – 9 months, age was not found to be a factor in homing behaviour. Stock or the hereditary factor, however, was found to be related to success in regaining the loft, though it did not appear to influence the accuracy of orientation shown by the departure flights. There is a suggestion that the height of the release point influences the immediacy of departure. Birds set free from the top of a 100 ft. tower vanished more quickly than pigeons released on the ground.
Observations on Luminescence in Renilla (Pennatulacea)
Authors: Nicol J. A. C.
Published: April 2021

Luminescence is well known in three groups of coelenterates, viz. Hydrozoa, Scyphozoa and Alcyonaria (literature reviewed by Harvey, 1952). Of these Pelagia, Pennatula and Renilla have been most intensively investigated. Observations indicate that in all these forms, light emission is under nervous control. Mechanical and electrical stimulation gives rise to a wave of light which passes over the surface of the animal (the disk in medusae, or the surface of the colony in hydroids and alcyonarians), at a rate which is consonant with nervous transmission as deduced from the spread of excitation concerned with muscular contraction. In his pioneering studies of the physiology of luminescence, Panceri (1872 a, b) found that localized stimulation of Pennatula excites luminous waves which spread up and down the colony, according to the position of excitation. Simultaneous excitation of the two extremities of an animal gives rise to two converging waves which cancel out on meeting. Parker’s (1920b) detailed study of Renilla, which will be referred to later, showed that luminescence is controlled by a nerve net, and that cuts made in any direction through the rachis still permit excitation to be transmitted so long as the stimulated region is not completely isolated, i.e. the nerve net is non-polarized.
A Simple Procedure for the Study of Ionic Regulation in Small Animals
Authors: Shaw J.
Published: April 2021

A simple procedure is described for the estimation of sodium, potassium, calcium and magnesium in quantities of about 1 µg. The ions are precipitated by specific chemical reagents, the precipitates separated by centrifugation and converted quantitatively into chlorides. The chloride is titrated by the Volhard method or by an electrometric method using a simple automatic micro-burette.

Measurements made on simple salt solutions and on blood samples gave standard deviations of 1-2% except in the sodium method where the error was greater (2-4%).
A Study of the Blood Groups of the Rabbit, with Reference to the Inheritance of Three Antigens, and the Agglutinability of the Red Cells Carrying Them
Authors: Joysey Valerie C.
Published: April 2021

Kellner and Hedal’s antigen G is identical with Heard’s antigen Z, and similarly g with Y. Kellner & Hedal’s (1953) conclusion that all rabbits must possess at least one of the antigens G or g was found not to be true of animals in this stock. Animals lacking both antigens were found to possess Heard’s antigen W. Z, Y and W form an allelomorphic trio. Heard’s evidence strongly suggests that the most agglutinable cells have more antigen sites (for the antibody in question), than less agglutinable cells. Evidence provided here shows that in the case of the Z and Y antigens homozygous cells are more agglutinable than heterozygous cells, and therefore probably have more sites of the Z or Y antigens respectively. Also the number of Y antigen sites is greater in Y Z than in Y W cells. It was not possible to demonstrate a similar difference for Z between Z Y and Z W cells. It is suggested that the notation of this allelomorphic trio in rabbits should be standardized as follows : Ga= Kellner & Hedal’s G and Heard’s Z; Gb = Kellner & Hedal’s g and Heard’s Y; Gc=Heard’s W.
Photo-Kinesis in the Ammocoete Larva of the Brook Lamprey
Authors: Harden Jones F. R.
Published: April 2021

Ammocoetes show no inherent rhythm of locomotory activity to parallel that demonstrated for their melanophores. They react ortho-kinetically to light above a threshold lying between 5.4 and 54m.c. Ammocoetes collect in the dark end of a light gradient at intensities below the threshold for ortho-kinesis. A klino-kinesis would appear to be the mechanism by which this aggregation is accomplished. All the evidence points to the conclusion that the locomotory reactions of the ammocoete to light bears no directional relationship to the source of stimulation and that they are entirely at random.
Wax Secretion in the Cockroach
Authors: Beament J. W. L.
Published: April 2021

The production of massive quantities of waxy materials by bees and similar insects has been known for a very long time, but it was not until 1938 that Bergmann showed the existence of smaller quantities of wax in the cuticle of Bombyx. Ramsay (1935) was the first to demonstrate that a greasy material on the surface of the cuticle was responsible for waterproofing the cockroach, and subsequently the work of Wigglesworth (1945) and Beament (1945) produced evidence for believing that the existence of a thin layer of wax in the epicuticle was widespread throughout the insects, and was the chief mechanism for restricting water-loss. It is now known that wax layers are also present in ticks (Lees, 1947) and in many arthropod eggshells (Beament, 1946, 1951, etc.), while Chibnall, Piper, Pollard, Williams & Sahai (1934) have carried out a detailed analysis of beeswax and of the wax of the white pine chermes. These waxes consist of long chain alcohols, paraffins and acids ; the aliphatic chains always appear to be saturated. The similarity of the physicochemical behaviour of cuticular waxes with beeswax, as outlined by Beament (1945), seems to leave little doubt that the minute but essential amounts of wax in typical insect cuticle are composed of the same type of chemical components as those found in beeswax. The range of melting-points of these materials shows that relative changes in the chain length of the component would be sufficient to account for the differences between the specific properties of waxes derived from different species.
The Nerves and Muscles of Medusae
Authors: Horridge G. A.
Published: April 2021

The responses of Geryonia proboscidalis to electrical and mechanical stimulation have been studied with particular attention to the transmission of excitation. There are two kinds of excitation transmitted across the undersurface of the bell; first, the symmetrical beat is co-ordinated by an isotropic conducting system which acts in a through-conducting, all-or-nothing manner, and produces brief contractions of the circular muscle; secondly, the movements of the manubrium are co-ordinated by a radial conducting system, which produces a maintained contraction of the radial muscles of the manubrium. The independence of these two conducting systems is shown by the simultaneous and yet distinct transmission of the two kinds of excitation in different directions. The contraction wave is not transmitted through the ring nerves faster than over the rest of the bell. The manubrium bends towards a stimulated tentacle, and all the tentacles contract simultaneously, co-ordinated by a through-conducting pathway in the marginal nerve. There is evidence that a polarized pathway carries excitation from this system to the rhythmical marginal centres. Observations of Geryonia held with the axis horizontal show that the steering action is due to an asymmetrical maintained contraction of the velum. The known histological details of the nervous system are compared with the physiological pathways demonstrated by experiment. The differentiation of a primitive isotropic nerve net into distinct tracts with separate functions is essential for the several rapid feeding and swimming activities.
The Behaviour of Barnacle Cyprids in Relation to Water Movement Over A Surface
Authors: Crisp D. J.
Published: April 2021

The velocity gradient of the fluid close to the solid boundary is the most appropriate description of the conditions of water flow which affect the attachment of the larvae of sessile forms to solid objects. The nominal speed of the water movement past the object is of importance only in so far as it influences the velocity gradient in the boundary layer. Experiments in glass tubes on cypris larvae of Elminius modestus and Balanus balanoides show that moderate velocity gradients exceeding 500 sec.-1 sweep the cyprids past the surface before they can attach. For large objects exposed to turbulent flow, the critical velocity gradient corresponds very approximately to a flow of 1-2 knots. Attachment under conditions of water flow is accompanied by negative rheotaxy, and can occur equally in the light and in the dark. Maximum attachment occurs at or below velocity gradients just great enough for the cyprid to be able to maintain position by swimming along the surface against the current. Once the cyprid has attached it cannot be pulled off the surface even by gradients greatly in excess of those which prevent attachment. Cyprids can migrate in all directions when exposed to moderate gradients, but they do so only with difficulty when the velocity gradient is high, particularly if the water is flowing in the same direction as that in which the cyprids are walking. The direction in which the cyprid migrates is altered only momentarily by changes in the direction of the current, the animal actively resisting the redistribution of forces acting on it. No direct evidence is given in this paper on the influence of water currents on fixation, but a critical comparison with other published work suggests that fixation can occur in places where the velocity gradients are greater than those which limit attachment, provided the cypris is able to migrate there after attachment. Moderate velocity gradients have little effect on the orientation at metamorphosis. Individuals tend to settle with the anterior end pointing downstream rather than in any other position. This orientation is the opposite from that which would be expected if the cyprid were passively orientated by the water current, but is likely to make subsequent feeding more efficient. The ability to attach under conditions of water flow, and the tendency not to attach under stagnant conditions, may have an important influence on the animals’ distribution and survival. Solid particles in suspension may profoundly influence the behaviour, hence the results given in this paper may not be relevant to conditions where scouring takes place.
Nervous Regulation of Luminescence in the Sea PansyRenilla Kollikeri
Authors: Nicol J. A. C.
Published: April 2021

Luminescence has been studied in the sea pansy Renilla kôllikeri, by means of photo-electric recording, and the mode of nervous regulation investigated. The luminescent response is under control of a non-polarized nerve net and is subject to facilitation which occurs terminally, at neuro-photocyte junctions. Facilitation is analysed in detail, and a facilitation-decay curve presented (Fig. 3). Between successive bursts of stimuli, facilitation may persist for some 10 min. Certain response parameters were measured. Latent period is o-12 sec. ; the response lasts 1 sec., and maximal intensity is reached in 0-22 sec. Conduction speed is 9 cm./sec. at 16-17° C. The refractory period of the response, as determined by high frequency stimulation, is o-2 sec. It is affected by fatigue and increases under repetitive stimulation. Under repetitive and prolonged stimulation, the animal passes into a hyper-excitatory state and luminous waves continue to arise long after stimulation has ceased. Conditions affecting this post-stimulatory discharge are examined. Comparison of facilitatory processes in quick muscular responses of sea anemones and luminescent responses of sea pens shows that they are essentially similar. From visual observations it appears that facilitation operates by recruitment of photocytes. Luminescence is of sporadic occurrence among coelenterates, and has been independently evolved on many occasions. It is suggested that its mode of regulation has been determined by the characteristics of the nerve net primarily concerned with control of muscles.
The Role of the Haemocytes in the Growth and Moulting of An Insect, Rhodnius Prolixus (Hemiptera)
Authors: Wigglesworth V. B.
Published: April 2021

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

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

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

Measurements 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

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

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

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

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.