bluuebunny/crossref_metadata_2025 huggingface dataset:
The Haemocytes and Connective Tissue Formation in an Insect, Rhodnius prolixus (Hemiptera)
Authors: Wigglesworth V. B.
Published: April 2021

The amoebocytes, which form the most abundant type of blood-cell in Rhodnius, contain rounded, oval, or rod-shaped inclusions which stain by the periodic acid /Schiff method. These are believed to be neutral mucopolysaccharides. The amoebocytes apply themselves to the basal membranes, which likewise are PAS-positive, and appear to contribute to these membranes by discharging their contents. They insinuate themselves into the developing muscles and give rise to the sheaths of connective tissue by which the muscle fibres are surrounded. And they collect around deposits of injected Indian ink, producing similar sheets of PAS-positive material, presumably mucopolysaccharide.

The chitinous endocuticle is PAS-negative (except in a few special regions such as the neck and the conjunctival membranes of the limbs). It becomes positive during digestion by the moulting fluid. The tracheae react similarly.

Other PAS-positive structures which are not produced by the amoebocytes are the striated border of the mid-gut, the basement membrane of the gut, the perilemma around the ganglia and nerves, and the ground substance within the ganglia.
The Histochemical Localization of β-Glucuronidase in the Liver of the Newt
Authors: Billett F. , McGee-Russell S. M.
Published: April 2021

The localization of β;-glucuronidase in the newt liver, by the use of quinolyl-8-glu-curonide as a substrate, is described. The technique previously used for the digestive gland of the Roman snail may be applied successfully to the newt tissue. Results suggest, however, that the treatments involved produce considerable destruction of the fine structure of the cytoplasm, and that present techniques based upon the precipitation of the ferric salt of 8-hydroxyquinoline cannot give a fine intracellular localization of the enzyme.
A Demonstration of Dehydrogenase Activity in the Mitochondria of Living Cells
Authors: Hughes Arthur
Published: April 2021

A method is described whereby fresh specimens of neural tissues are examined in squashes under the phase microscope. When squashed in contact with the sensitive tetrazolium derivative known as ‘INT’, granules of formazan are precipitated around the mitochondria within the neurocytoplasm. Application of these techniques to squashes of the spinal cord of the ray has given a direct demonstration of the dehydrogenase activity of mitochondria within fibres of the white matter of the cord.
The Cytoplasmic Inclusions of the Neurones of Certain Insects
Authors: Malhotra S. K.
Published: April 2021

A comprehensive study of the thoracic neurones of fifth instar and immature adults of the locust, Schistocerca gregaria Forsk., and of adults of the water-bug, Laccotrephes rubra Fabr., has been made by employing the latest cytological techniques and phasecontrast microscopy. The mitochondria are seen as granules stainable in life with Janus green. Alignment of granules into filamentous mitochondria has also been observed in fixed preparations. The Golgi bodies (lipochondria of Shafiq) are sudanophil, osmio-phil, and argentophil spheroids. The bigger spheroids show a duplex structure. There is a chromophil, cortical, lipid component, which may be in the form of a complete ring (Schistocerca) or in the form of one or two granules or a crescent (Laccotrephes), and a chromophobe medulla stainable with the basic dyes, neutral red and methylene blue. The smaller Golgi bodies in Schistocerca show a homogeneous structure. The Golgi bodies have not been observed to be engaged in any secretory activity. Neurofibrillae have been observed in the neurones of the insects studied.
The Origin of the Spermatophoric Mass of the Sand Crab, Hippa pacifica
Authors: Matthews Donald C.
Published: April 2021

In Hippa pacifica, mitotic division of germinal epithelial cells produces primary spermatocytes which, as sustentacular-like cells appear, divide meiotically to form spermatids. Concurrently as spermatids metamorphose into spermatozoa, germinal epithelial cells renew their activity and again produce primary spermatocytes which, as they fill the sacculus, expel the spermatozoa. A continuous spermatogenic mass enters the vas deferens, where an enveloping secretion from the epithelial cells bounding the lumen forms a thin sheath to the sperm mass. The lumen (viewed in cross-section) becomes keyhole-shaped and a secretion from a wedge-shaped group of cells bounded by two deep crypts both surrounds the sheathed sperm mass and forms a ribbon-like supporting stalk and a broad, basal foot. As the lumen again becomes circular (in cross-section), a secretion from the epithelial cells surrounds the completed spermatophore and forms the homogeneous matrix. The spermatophore of H. pacifica is both macruran-like, because of its continuous, highly convoluted sperm mass, and anomuran-like, because of its raised spermatophore and broad foot. Neither the anomuran-like spermatophore of a macruran, Parrabicus antarcticus, nor the macruran-like spermatophore of an anomuran, Hippa pacifica, justifies the inference that these two animals occupy a systematic position intermediate between the Macrura and the Anomura, but rather illustrates the need for consideration of many characters before postulating relationships.
Studies of Serpulid Tube Formation: II. The Calcium-secreting Glands in the Peristomium of Spirorbis, Hydroides, and Serpula
Authors: Hedley R. H.
Published: April 2021

Descriptions of the calcium-secreting glands, which produce the calcareous component of the tubes, are given for Spirorbis, Hydroides, and Serpula. In Hydroides the gland is a simple tubule. The gland in Spirorbis is tubular but the gland-cells have unusual extensions which project into the lumen. In the centre of these extensions there is always a strongly basiphil substance. In Serpula the glands are tubulo-racemose or compound tubular, similar to those in Pomatoceros.

In addition to the calcium-secreting glands in Serpula there are two ventral calcium sacs in the posterior part of the peristomium which secrete calcareous material. The sac wall has a peculiar structure, being non-cellular and consisting of two layers, one basiphil the other acidophil. In the acidophil part two layers are seen, one fibrous and the other optically homogenous in which numerous small bodies are found.
A Histochemical Study of the Organic Matrix of Hen Egg-Shells
Authors: Simkiss K. , Tyler C.
Published: April 2021

A study of the organic material of the hen egg-shell has been made by the use of recognized histochemical techniques.

It has been found that, in the so-called spongy layer of the shell, the organic matrix consists of a protein / acid mucopolysaccharide complex. The organic material of the mammillary layer appears to be more concentrated in a central core, and is somewhat different in that it contains fat and a reducing substance.

The protein / acid mucopolysaccharide complex is a collagen-like material, but is probably not collagen itself because the protein portion is low in hydroxyprob’ne and the acid mucopolysaccharide is most likely mucoitin and not chondroitin sulphuric acid.

The results are discussed in relation to shell calcification and it is suggested that the protein / acid mucopolysaccharide complex is first firmly attached to the keratin of the membrane, but once this is accomplished it links on to material of its own kind. Calcification proceeds simultaneously, but near the points of contact with the membrane (i.e. in the core of each mammilla) calcification is not so intense as it is in the rest of the shell.
The Cytoplasmic Inclusions of the Neurones of Helix aspersa and Limnaea stagnalis
Authors: Chou J. T. Y.
Published: April 2021

1. The only cytoplasmic inclusions visible in the living neurone are lipid globules and mitochondria.

2. In both Helix and Limnaea there are three kinds of lipid globules, as follows :

(a) large globules, yellowish from their carotinoid content;

(b) smaller globules, easily coloured by vital dyes ;

(c) small globules, not colourable by vital dyes.

3. The crescents and rings (‘dictyosomes’) seen in ‘Golgi’ preparations appear to be formed by the deposition of silver or osmium on the distorted contents of the smaller globules that are easily coloured by the vital dyes.

4. No crescents or rings are seen in the cytoplasm of the living cell.

5. The mitochondria are long, thin threads.
Observations on Photophores and Luminescence in the Teleost Porichthys
Authors: Nicol J. A. C.
Published: April 2021

Porichthys myriaster is a shallow-water teleost possessing numerous photophores on head and trunk. These are embedded in the dermis and consist of a lens, layer of photogenic cells, and reflecting sheath. The photophore receives a nerve and bloodvessels which proceed to the photogenic tissue. The photogenic cells are finely granular and stain poorly. Luminescence in the living fish was evoked by electrical excitation and injection of adrenaline. When the nerve-cord was stimulated by electric shocks, the photophores lit up after a latent period of 7-10 sec. With localized stimulation a response was still obtained from all the photophores of the body after transection of the nerve-cord and arrest of circulation. Injection of adrenaline into the heart caused widespread luminescence in 2 min. The pattern of innervation of the photophores in teleosts suggests an autonomic supply. It is concluded that the photophores of Porichthys are probably innervated by the sympathetic system. Efferent fibres may be adrenergic. If the adrenals are involved, their effect is secondary, following nervous excitation.
A Morphological and Histochemical Study of the Oocytes of the Fish, Ophiocephalus punctatus, with particular Reference to Lipids
Authors: Chopra H. C.
Published: April 2021

The cytoplasmic inclusions of the growing oocytes of the fish, Ophiocephalus punctatus, have been studied both morphologically and histochemically. It has been observed that the non-yolky oocytes of early stages consist of granules of two types, namely the mitochondria and the lipid granules of first category (L1). The mitochondria are smaller granules, and they are found to be protein in nature with traces of lipids. The bigger granules (L1) consist of phospholipids only; they correspond to the so-called ‘Golgi bodies’ of earlier workers on fish oocytes. The yolk found in the late oocytes is of two types. The first type of yolk globules, which appear with the approach of the breeding season, consist of lipids only, and have been described as lipid bodies of the second category (L2). At first they are spheres consisting of phospholipids and triglycerides, but in the mature eggs they are transformed into big fat globules containing triglycerides only. The second type of yolk, which appears later, is in the form of spheres, rich in proteins and lipoproteins. Lastly there is ‘vacuolar yolk’, rich in carbohydrates and proteins; this develops in vacuoles.
Histochemical Observations on the Cortical Region of the Oocytes of Rana pipiens
Authors: Rosenbaum R. M.
Published: April 2021

The cortical cytoplasm of the developing oocyte of Rana pipiens has been investigated by cytochemical means. Particular emphasis is placed on the nature and distribution of polysaccharide protein complexes. With toluidine blue O, both living and fixed mature oocytes were found to possess a distinct metachromatic region just under the developing vitelline membrane. Younger oocytes, at the previtelline-stage, did not exhibit metachromasia in this region. Comparative studies suggested a similarity of oocyte cortical metachromasia to that of mucoitin sulphuric acid. Oxidation by periodic acid and staining with the Schiff reagent or 2,4-dinitrophenylhydrazine or both, demonstrated reactive granules located in the cortex of both young and mature oocytes. The presence of more than one polysaccharide component was suggested. Hydrolysis with trypsin and chymotrypsin indicated that the proteins in the ectoplasmic region were more readily digestible than those in the endoplasm.
Some Cytological Features of Epididymal Cells in the Rat
Authors: Reid B. L.
Published: April 2021

Living material was photographed by phase-contrast miscroscopy. Fixed material was stained for mitochondria or post-osmicated.

The findings show a close conformity between the pictures in living and fixed cells, except that the so-called Golgi apparatus, whilst very apparent in some zones by both techniques, in other zones is well represented after osmication but not in the living cell. Reasons for this are proposed.

Studies by earlier workers on the mitochondrial pattern are confirmed. There is an increased density and decreased length of rods down the length of the epididymal duct. The relationship of the chondriome to the osmiophil material varies in the different zones; in some, close association with permeation is found, while in others the separation is complete.

General observations upon living epididymal cells are recorded. These include the effects of different suspending media and the changes undergone by the cells after their isolation. A close study has been made of the free (stereociliated) border of the cells.
Histochemical and Morphological Studies of the Lipids in Oogenesis. I. Periplaneta americana
Authors: Nath Vishwa , Gupta Brij L. , Lal Bachan
Published: April 2021

Three kinds of lipid bodies have been described in the oogenesis of the cockroach, Periplaneta americana: (i) L1 bodies, present in the earliest oocyte, which persist till the oocyte measures approximately 0·5 mm and contain phospholipids only, possibly having more lecithins than cephalins; (ii) L2 bodies, which first arise in the oocyte measuring 0·4 mm and have a complete or incomplete sheath of phospholipids sur-rounding a medulla of triglycerides (rather highly saturated); (iii) L3 bodies, which are the only type of lipids present in the oocytes measuring more than 0-65 mm and consist of triglycerides only (rather highly saturated). Some of the larger L3 bodies give a ‘ringed’ or ‘crescentic’ appearance in Sudan black when used at room temperatures (12° C to 40° C) but appear mostly solid when this colouring agent is used at 6o° C. Mitochondria, which remain as fine granules throughout the course of oogenesis, contain proteins and phospholipids. They seem to have some lipids which are masked normally but are unmasked after acetone extraction, with a resulting increase in sudanophilia. Yolk globules appear in the oocytes measuring approximately 0 ·5 mm. They contain a protein-carbohydrate complex. The bacterioid objects described by earlier workers have been shown to contain phospholipids and free fatty acids. They possibly play an active role in the lipid synthesis of the cell.
The Co-ordination of Growth in the Tracheal System of Insects
Authors: Locke M.
Published: April 2021

The tracheae in Rhodnius and many other insects are parallel-sided tubes which branch in such a way that the cross-section of the diffusion path remains constant. Growth in length results mainly from stretching the trachea in the preceding instar. Growth in diameter of the tracheae varies with feeding and the organ supplied. The proportions of the tracheal system are maintained by co-ordination of the growth of the main tracheae and new terminal branches. This is brought about by the property of tracheae which enables them to react to stimuli for growth only upon the spiracle side of the point of application. The stimuli for growth probably originate from the tissues and from the nodes. They determine first the diameter of the tracheae farthest away; that is, the tracheae begin to form at the spiracles. The nodes controlling the diameter of the lateral tracheae are influenced by the blood.

Growth in the tracheal system of Tenebrio larvae varies inversely with the oxygen tension both above and below atmospheric.
Observations on the Innervation of the Integument of Amphioxus, Branchiostoma lanceolatum
Authors: Lele P. P. , Palmer Elisabeth , Weddell G.
Published: April 2021

In this paper the pattern of innervation of one of the simplest forms of skin, the integument of amphioxus (covering the dorsal fin in the middle third of the animal) is compared and contrasted with that of the cornea and of the skin in man.

An account is given of the results of stimulation experiments in which the integument in this region was irradiated with infra-red rays.

The observations which have been made can be summarized briefly as follows:

No neuro-epithelial cells were encountered in the epidermis in the region chosen for study. Evidence is given which suggests that the nuclei along the course of the nerve-trunks which combine to form the ‘dorsal roots’ of the nerve-cord are not those of the first sensory neurone. They appear to be analogous to the Schwann-cell nuclei of vertebrates. The ratio of epidermal cells to parent sensory axons in randomly selected metameres of integument in the selected region is as low as 7:1. From this it has been calculated that the density of innervation is comparable with that in the cornea and in the skin of vertebrates. Every epidermal cell has two or more terminal filaments ending in relationship to it. Pre-terminal axons from parent axons of different diameters are widely and apparently randomly scattered beneath the epidermis. Each and every epidermal cell is related to terminals which approach from different directions and serve more than one parent axon. The patterned arrangement of the nerves serving the integument of amphioxus is comparable with that observed in the skin of teleost fish, in the cornea of a number of vertebrate species, and in the skin of man. The nerves in the integument in the selected region can transduce non-injurious infra-red stimuli, although the stimuli were of a kind not normally encountered by the animal in its natural habitat. In the light of these observations and of experimental observations in man (Weddell, 1955; Lele and Weddell, 1956; Weddell, 1957), it is difficult to subscribe to the notion that information concerning the environment is transmitted to the central nervous system from the skin by a restricted series of nerves having terminals which only transduce stimuli having quite specific physical attributes. Rather, it seems likely that information reaches the central nervous system in the form of a space-time pattern of action potentials from endings which are either more or less available to a range of stimuli having different physical characteristics. In other words, different stimuli must evoke different patterns of activity, which are analysed by the central nervous system acting in a role of an analogue as opposed to a digital computer.
The Nature and Origin of Yolk
Authors: Rogers Brambell F. W.
Published: April 2021

The advance of modern cytology has necessitated the division of the cytoplasmic inclusions into two groups, the protoplasmic inclusions or living organellæ capable of spontaneous growth, division and movement within the cell, and the deutoplasmic inclusions or non-living reserve materials of the cell built up by the activity of the living protoplasm, representing a stage in the anabolic processes of the cell. The Golgi apparatus and the mitochondria both belong to the former group and appear, in the present state of our knowledge, to be specially associated with cell anabolism and often, if not always, in oögenesis with the special case of yolk formation. Sometimes the yolk is produced indirectly by the action of these organellæ, at other times either the Golgi elements or the mitochondria swell up and themselves transform into yolk spheres. In the latter case it is difficult to decide whether an element at any given stage of the transformation process should be considered a deutoplasmic or a protoplasmic body.
The Effect of Salts on the Anal Gills of the Mosquito Larva
Authors: Wigglesworth V. B.
Published: April 2021

While studying the function of the anal gills of the mosquito larva (Wigglesworth, 1932) I had occasion to observe the effects of certain electrolytes upon them, and these effects seemed sufficiently unusual to deserve separate study. Their curious character is due, no doubt, to the unusual structure of the cells in question, but it is possible that some of these observations may throw light upon the behaviour of other types of cell in the animal body. In any case it will be desirable to record them before discussing the function of the so-called anal gills themselves.
The Adaptation of Mosquito Larvae to Salt Water
Authors: Wigglesworth V. B.
Published: April 2021

It is well known that the larvae of certain mosquitoes can thrive both in fresh water and in water of a high degree of salinity, while the larvae of other mosquitoes are quickly killed by salt water ; and that such differences may exist even between local races of the same species (Evans, 1931). It is evident that we have here to deal with a physiological adaptation, and it was the object of the present work to discover what the nature of this adaptation might be.

The physiological properties of larvae of the yellow-fever mosquito (Aedes (Stegomyia) argenteus Poir), which were accustomed to salt water, have been compared with those same properties in normal larvae. It so happens that this particular larva is unable to tolerate very salt water ; but it is probable that the relatively small degree of resistance which it can acquire is of the same kind as that occurring in more tolerant species, and therefore the mechanism of this resistance may throw light upon the general problem.
Induction by the Primitive Streak and its Derivatives in the Chick
Authors: Waddington C. H.
Published: April 2021

It has recently been shown (Waddington, 1932) that in the chick embryo a developing primitive streak can cause any ectoderm lying above it (provided only that the ectoderm is of the right age) to differentiate into a neural plate. It was shown that in all successful cases the grafted primitive streak had yielded both neural tissue and mesoderm, but that in some specimens the grafted neural tissue was very small in amount and was not in contact with the host ectoderm, and from this fact it was concluded that the mesoderm is capable of acting as an organiser in the absence of neural tissue. The first specimen to be described in this paper confirms this conclusion, since in this case the grafted tissue has given rise only to mesoderm, and this uncontaminated mesoderm has induced the formation of a neural plate from the host ectoderm.
Carbon Dioxide as A Sex-Determining Factor in Moina Macrocopa
Authors: Stuart C. A. , Cooper H. J. , Coady Harriet
Published: April 2021

The role of food and metabolic products in the control of sex in Cladocera has received considerable attention in the last one or two decades. Practically all the evidence favouring excretory substances as sex-controlling agents has been derived from the fact that crowded mothers produce a much higher percentage of male young than isolated mothers. It is self-evident that crowding Cladocera must favour the accumulation of metabolic products, but the results of crowding cannot be confined solely to the accumulation of the animals’ waste products. Food must also be considered as contributing to any effects that the crowding may have on the sex of the young produced by crowded mothers. The work of Woltereck (1911), Tauson (1930), Stuart and co-workers (1929, 1931 a, b, c, d, 1932 a, b) and numerous others on food has led many investigators to conclude that, of the two factors in question, food is the more important sex-controlling agent under ordinary conditions.
Intracellular Oxidation-Reduction Studies
Authors: Chambers Robert , Beck Lyle V. , Green David E.
Published: April 2021

In a previous communication (1) of this series on the permeability of Echinoderm eggs to the oxidation-reduction indicators of the Clark and Cohen series it was observed that none of the sulphonic acid indicators entered the eggs whereas all the others of the series penetrated with ease. Moreover, it was shown that any possible extracellular oxidation-reduction reaction of Echinoderm eggs, or, for that matter, of sea water, is of negligible importance compared with the reaction inside the cells. It followed that the sulphonated indicators can serve their purpose only when the permeability factor is ruled out, viz. in micro-injection studies, and in immersion experiments with cytolysed material.
Observations on the Functions of the Alimentary Canal in Fowls
Authors: Henry K. M. , Macdonald A. J. , Magee H. E.
Published: April 2021

The work recorded in this paper is a continuation and amplification of the study of alimentary function in the fowl begun by MacOwan and Magee (1931) and, like it, deals with the passage of food through, and the absorption of carbohydrates from, the digestive tract. The technique employed in the study of these questions was varied, and it has, accordingly, been found convenient for descriptive purposes to divide the paper into two parts.
Metabolic Changes Associated with Endocrine Activity and the Reproductive Cycle in Xenopus Laevis
Authors: Zwarenstein H.
Published: April 2021

The ease and rapidity with which the whole pituitary or part of the gland can be removed in Xenopus laevis, the low post-operative mortality and the fact that the animals survive the operation for more than two years, suggested an investigation into the relation between the pituitary and several metabolic variables. In a previous paper (Shapiro and Zwarenstein, 1933) the effect of hypophysectomy on the calcium content of the serum was reported. The prominent part played by the pituitary in regulating the water-salt content of the tissues was suggested by the work of Stehle (1926) on the diuretic-antidiuretic action of pituitary extracts. In Xenopus the low level of serum calcium which occurred as a result of pituitary re-moval was never associated with tetanic symptoms. These considerations and the well-known antagonism between calcium and potassium in all biological phenomena suggested an enquiry into the effects of hypophysectomy on serum potassium.
Observations on the Nutrition of Maggots of Australian Blow-Flies
Authors: Mackerras M. J. , Freney M. R.
Published: April 2021

Larvae of L. cuprina and Ch. rufifacies are capable of liquefying and digesting protein media without the intervention of bacteria. Both species and L. sericata secrete tryptic and peptic enzymes and at least L. cuprina does so from the moment of hatching. Tryptase is more abundant than pep tase. Predatory activity, though a normal habit of Ch. rufifacies, is not necessary for any of these species and did not occur in the masses of Lucilia larvae used for extraction of the enzymes, although they were kept for periods up to 24 hours without food. Partial development of larvae occurred in sheep dung, faeces-stained wool and in the products of keratin hydrolysis. Complete development took place in wool containing a “gummy crust” of dried exudate and in. some samples of faeces-stained wool. Some of the samples of faeces-stained wool and those containing a “crust” have been demonstrated serologically by Dr I. M. Mackerras to have an increased content of soluble sheep protein as compared with normal wool. A marked increase of soluble protein has been demonstrated in struck wool both chemically and serologically. Moisture, warmth, shelter and aeration are essential physical conditions for larval development. In addition, an alkaline reaction is relatively favourable and an acid reaction relatively unfavourable. There are normally two stages in the development of a primary strike, the first stage being from hatching up to the time the larvae attack the skin, the outer layer or epidermis of which is approximately 36µ thick (Whitnall, 1931). During this stage they must feed, if at all, on materials already present. The second stage is from the commencement of an actual skin lesion up to full development of the maggots. During this stage there is a more or less copious serous exudation, which has been shown to be an adequate food for the full development of the maggots. Faeces-staining, presence of exudate due to a prior lesion, and products of wool hydrolysis have been shown to be adequate to carry the larvae through the first stage. Wool hydrolysis on the living sheep is probably not an important factor, judging by an examination of wool samples, but we have isolated organisms which, when growing on a nutrient medium, are capable of disintegrating wool fibre. The role of bacterial activity in strike is complex and appears to be substantially as follows : (a) to produce substances which attract the flies and stimulate them to oviposit ; (b) to provide food for the initial growth of the maggots, either by rendering assimilable the inert proteins, or by causing a skin reaction with a serous exudation. The immediate work for the future is a more exact determination of: (a) the nature of the food of the larvae in the early stage of growth on the living sheep; (b) the factors which influence its production ; and (c) the mechanism by which the larvae invade the skin.
The Effects of Hypophysectomy and Anterior Lobe Administration on the Skin and Thyroid of Triton Cristatus
Authors: Adams A. Elizabeth
Published: April 2021

The skins of many vertebrates react to variations in the amount of hormones of the endocrine glands, especially of the thyroid and pituitary. Moulting in Triturus viridescens is inhibited after both thyroidectomy and hypophysectomy or both operations simultaneously performed. The cornified layers continue to form and the accumulation of these makes the animal appear grimy (Adams and Richards, 1929; Adams, Richards and Kuder, 1930; Adams, Kuder and Richards, 1932). The series of experiments here reported demonstrates that a similar effect occurs after hypophysectomy in immature or mature Triton cristatus (Adams, 1931a). The moult in Triturus viridescens operated in the above ways can be induced by various methods. Supplying thyroid hormone by thyroid grafts or thyroxin injections, or administering iodine to thyroidectomised or hypophysectomised animals or to ones lacking both glands, or stimulating the thyroid glands of hypophysectomised animals either by giving pars anterior grafts or injections or by pinching them in situ, will cause the shedding of the cornified layers (Adams et al. 1930, 1932; Adams, 1931 b, 1932). Similarly in hypophysectomised Triton cristatus, the moult can be induced by administration of pars anterior substance or by injection of certain extracts of mammalian anterior lobe.
The Defence-Arousal System and its Relevance for Circulatory and Respiratory Control
Authors: Hilton S. M.
Published: April 2021

It was proposed some fifty years ago that the visceral and hormonal changes accompanying fear and rage reactions can best be understood as adaptations which prepare an organism to cope with an emergency and specifically to perform the extreme muscular exertion of flight or attack. This is well exemplified by the pattern of cardiovascular response which is characteristic of the alerting stage of these reactions and consists of an increase in cardiac output directed mainly to the skeletal muscles.

This group of behavioural responses has been collectively termed the defence reaction. The regions of the hypothalamus and brainstem which organize it have been mapped. They function as a reflex centre for the visceral components of the altering response as well as initiating the behavioural response. So far as the cardiovascular system is concerned, this is a preparatory reflex and not compatible with short-term homeostasis. Indeed, the baroreceptor reflex, which is homeostatic, is strongly inhibited. By contrast, the chemoreceptor reflex is facilitated. The input from peripheral chemoreceptors is itself an alerting stimulus.

The visceral alerting response has been studied in most detail in the cat, but there is evidence for the same cardiovascular pattern and an accompanying group of respiratory changes in other mammalian species (rat, rabbit, dog, monkey and man).

On the efferent pathway for the cardiovascular response pattern, there is a group of relay neurones near the ventral surface of the caudal medulla, which seem important for the maintenance of arterial blood pressure. The visceral alerting system may therefore be continually engaged to some extent in the awake state, as well as being acutely activated in response to novel, and especially to noxious, stimuli.
Respiratory and Cardiovascular Control During Diving In Birds and Mammals
Authors: Butler P. J.
Published: April 2021

Recent studies on freely diving birds and mammals indicate that, contrary to the classical hypothesis, the majority of dives are aerobic with minimal cardiovascular adjustments (i.e. bradycardia and selective vasoconstriction). It is postulated that during these aerobic dives the cardiovascular adjustments result from the opposing influences of exercise and the classical diving response, with the bias towards the exercise response. It is envisaged that the active muscles, as well as the brain and heart, are adequately supplied with blood to enable them to metabolize aerobically. Intense mental activity, particularly in carnivores seeking their prey, may also attenuate the classical response. Aerobic dives are usually terminated well before the oxygen stores are depleted, and another dive follows once they have been replenished. In this way a series of dives is performed.

Prolonged dives are endured as a result of a shift towards the classical response of bradycardia, presumably more intense vasoconstriction, and anaerobiosis. This may be a form of alarm response, particularly in small animals such as ducks and coypus, or it may be a means of allowing the marine birds and mammals that dive deeply for their food to engage in unusually long hunting expeditions. For those that dive under ice, it may also allow long periods of underwater exploration as well as being a safety mechanism should the animal become disoriented.
Respiratory and Circulatory Control During Sleep
Authors: Coote J. H.
Published: April 2021

A survey of the literature on a large number of vertebrate animals shows that sleep is associated with profound cardiovascular and respiratory adjustments which are very similar in each species. A hypothesis is advanced that these adjustments are ‘goal directed’ by neural structures in the brainstem, to ensure an adequate O2 and CO2 transport to and from the brain whilst at the same time reducing energy cost. During synchronised sleep there is a vagal bradycardia leading to reduced cardiac output and a fall in blood pressure; despite this cerebral blood flow increases. During desynchronized sleep there is a tonic fall in blood pressure and heart rate resulting from a unique repatterning of sympathetic discharge, that to heart, kidney, splanchnic and pelvic vascular beds decreasing whilst that to skeletal muscle increasing ; cerebral blood flow shows a further increase. This differential pattern is probably initiated by neurones located in the caudal raphe nucleus obscurus. Phasic increases in blood pressure and heart rate also occur during desynchronized sleep mainly as a consequence of increases in sympathetic activity. Ventilation decreases during synchronized sleep accompanied by an increase in partial pressure of arterial CO2, which vasodilates cerebral blood vessels, indicating that the influence of CO2 on the level of ventilation has changed. During desynchronized sleep ventilation increases and becomes very irregular but the partial pressure of O2 and CO2 in arterial blood is little changed from wakefulness. Control of respiration is shifted to a central generator which apparently is different to the automatic/ metabolic one which is normally dominant during wakefulness. Reflex control of the circulation and respiration is mainly governed by peripheral chemoreceptors, the threshold of most other afferent inputs being significantly raised during sleep.
Control and Co-Ordination of Ventilation and Circulation in Crustaceans: Responses to Hypoxia and Exercise
Authors: Taylor E. W.
Published: April 2021

The functional morphology, nervous and hormonal control and coordination of the cardiovascular and ventilatory systems in decapodan crustaceans is reviewed. Pacemaker function reflects the reliance of crustaceans on small numbers of large, multipolar neurones. Respiratory gas exchange and transport may be limited by the potential diffusion barrier presented by chitin on the gills and by the relatively low O2 capacity of the haemolymph, though this is compensated by the relatively high O2 affinity of haemocyanin and the large volume of the haemocoel. Haemolymph buffering capacity is attributable to haemocyanin and to bicarbonate, including an internal source of fixed base, possibly the exoskeleton.

The typical hypoxic response includes a bradycardia and hyperventilation resulting in a respiratory alkalosis and resultant increase in O2 affinity of the haemocyanin. Diffusive conductance may increase. When 02 transport is limiting there is a switch to anaerobiosis with normoxic recovery including repayment of an O2 debt. Some species are facultative air-breathers and compensate for a respiratory and metabolic acidosis when in air by elevation of buffer base. Central and peripheral O2 receptors may be involved in determining respiratory and cardiovascular responses to hypoxia and airbreathers may respond to changes in haemolymph pH. Exercise induces a rapid increase in ventilation, diffusive conductance improves and O2 consumption is elevated. There is also a major anaerobic contribution causing a metabolic acidosis and recovery includes prolonged repayment of an O2 debt.
Pulmonary And Respiratory Tract Receptors
Authors: Widdicombe J. G.
Published: April 2021

Nervous receptors in the lungs and respiratory tract can be grouped into four general categories.

Deep, slowly adapting end-organs, which respond to stretch of the air-way wall and have large-diameter myelinated fibres; those in the lungs are responsible for the Breuer–Hering reflex. Endings in and under the epithelium which respond to a variety of chemical and mechanical stimuli (i.e. are polymodal), usually with a rapidly adapting discharge, and with small-diameter myelinated fibres; they are responsible for defensive reflexes such as cough and sneeze, and for the reflex actions to inhaled irritants and to some respiratory disease processes. Receptors with nonmyelinated nerve fibres which, being polymodal, are stimulated by tissue damage and oedema and by the mediators released in these conditions ; these receptors may be similar in function to * nociceptors’ in other viscera, and set up appropriate reflexes as a reaction to respiratory damage. Specialized receptors such as those for taste and swallowing, and those around joints and in skeletal muscle.

Stimulation of any group of receptors may cause reflex changes in breathing (including defensive reflexes), bronchomotor tone, airway mucus secretion, the cardiovascular system (including the vascular bed of the airways), laryngeal calibre, spinal reflexes and sensation. The total pattern of motor responses is unique for each group of receptors, although it is probably unusual for one type of receptor to be stimulated in isolation. The variety of patterns of motor responses must reflect the complexity of brainstem organization of these systems.
Limb Mechanics as A Function of Speed and Gait: A Study of Functional Strains in the Radius and Tibia of Horse and Dog
Authors: Rubin Clinton T. , Lanyon Lance E.
Published: April 2021

Rosette strain gauges were attached to the midshaft of the radius and tibia of two horses and two dogs, which ran on a treadmill through their entire range of speed and gait. The relative magnitudes of the principal strains on the opposite cortices of each bone remained constant through the stance phase of the stride, and their orientation varied by a maximum of only 14° through the entire speed range. The maximum strain rate increased linearly with speed, but the peak strain magnitude was also dependent upon the gait used, increasing incrementally by up to 59% at the transition from walk to trot, and dropping by 42 % from a trot to a canter. Force transducers attached to the shoes of one horse indicated similar changes in ground load.

The peak strains induced during vigorous activity are remarkably uniform in a wide range of animals. This suggests that the skeleton is scaled to provide constant safety margins between peak functional strains and those at which yield and ultimate failure occur.
Acid-Base Balance in Callinectes Sapidus During Acclimation from High to Low Salinity
Authors: Henry Raymond P. , Cameron James N.
Published: April 2021

When transferred from 865 to 250 m-osmol salinity, the blue crab C. sapidus maintains its blood Na+ and Cl− concentrations significantly above those in the medium. When branchial carbonic anhydrase is inhibited by acetazolamide, ion regulation fails and the animals do not survive the transfer. An alkalosis occurs in the blood at low salinity, indicated by an increase in HCO3− and pH at constant . The alkalosis is closely correlated with an increase in the Na+–Cl− difference, a convenient indicator of the overall strong ion difference. The contribution’ of changes in to acid-base changes was negligible, but the change in the total weak acid (proteins) may be important. It is suggested that the change in blood acidbase status with salinity is related to an increase in the strong ion difference, which changes during the transition from osmoconformity to osmoregulation in the blue crab, and which is related to both carbonic anhydrase and ion-activated ATPases.
Reflex Effects of the Femoral Chordotonal Organ Upon Leg Motor Neurones of the Locust
Authors: Field L. H. , Burrows M.
Published: April 2021

The femoral chordotonal organ (FCO) in a hind leg of a locust monitors the position and movement of the tibia about the femur. It consists of a group of sensory neurones embedded in connective tissue attached distally by two structures: the apodeme, which inserts close to the apodeme of the extensor tibiae muscle, and the flexor strand, which inserts at the base of the apodeme of the flexor tibiae muscle. The action of the apodeme and the flexor strand is reciprocal during movements of the tibia; the apodeme is stretched during flexion of the tibia whilst the flexor strand is relaxed. During extension, the apodeme is relaxed and the flexor strand is stretched. To analyse the reflex effects of this sense organ, all other sense organs of a hind leg were denervated. The apodeme of the FCO was then grasped between forceps, severed from its distal attachment site and its movements controlled by a function generator. The flexor strand remained intact and could be stimulated independently by moving the tibia.

The different reflex effects mediated by the separate stimulation of the two components of the FCO were revealed by making intracellular recordings from the somata of leg motor neurones in the metathoracic ganglion. A movement stimulus to either component in a way that corresponded to tibial extension, excited flexor tibiae and inhibited extensor tibiae motor neurones. There was also an inter-joint effect whereby extension excited the depressor tarsi and inhibited the levator tarsi motor neurones. A flexion movement had the converse effects on these motor neurones.

The effectiveness of the two components was dependent upon the velocity of the stimulus, the set position of the femoro-tibial joint at which the stimulus was applied, the initial direction of movement, and the activity of other neurones in the central nervous system. Slow motor neurones were depolarized more by low velocities of movement, whereas fast ones were depolarized more by high velocities. The two components produced their greatest effects at the set positions where they were most stretched ; thus the apodeme was most effective when the joint was flexed, and the flexor strand when it was extended.

Elicited movements of the hind legs or apparently spontaneous changes of excitability enhanced or masked the typical response of the motor neurones to stimulation of the FCO, indicating that the effects of this sense organ are not to be viewed as rigid, but as modifiable in the context of the behaviour of the animal.
The Control System of the Femur-Tibia Joint in the Standing Leg of A Walking Stick Insect Carausius Morosus
Authors: Cruse H. , Schmitz J.
Published: April 2021

The control system of the femur-tibia joint of the stick insect (Carausius morosus) shows different properties depending on whether the animal is standing or walking. The properties of the system were examined when the animal was walking on a treadwheel and when the examined leg rested on a platform fixed beside the wheel. The results show that the properties of the system in the standing leg of a walking animal are similar to those of a walking animal rather than those of the standing animal. This indicates that the state of the leg (standing or walking) does not seem to be controlled by the neural subsystem of the leg itself but by a more generalized system, which differs in its properties depending upon whether the whole animal is standing or walking. Furthermore the results show how the behaviour of the system changes for the two alternative states.
Modulation of Synaptic Transmission and Excitation-Contraction Coupling in the Opener Muscle of the Crayfish, Astacus Leptodactylus, By 5-Hydroxytryptamine and Octopamine
Authors: Fischer Ludwig , Florey Ernst
Published: April 2021

The modulatory actions of 5-hydroxytryptamine (5-HT) and octopamine (OA) were investigated in the opener nerve-muscle preparation of the crayfish, Astacus leptodactylus. Membrane resistance and resting potential were unaltered by 5-HT and OA at concentrations up to 2·5 × 10−5 M; but EPSP-amplitudes were increased, up to 3-fold by OA and up to 18-fold by 5-HT. The lowest effective concentration was 2·5 × 10−9M; a maximal effect was produced at 2·5 × 10−6M. The effect was reversible only after prolonged washing. The enhancement of EPSPs by 5-HT or OA is due to an increased amplitude of the synaptic current; the current duration is not altered. The facilitation ratio (ratio of amplitudes of a pair of EPSPs) is not significantly affected by 5-HT or OA despite the often enormous increase of the absolute EPSP-amplitudes.

The modulatory action also affects the excitation-contraction (e-c) coupling process: the effectiveness of e-c coupling was increased 7·4-fold by 5-HT (2·5 × 10−6M) and 18-7-fold by OA (5 × 10−6M). The threshold potential of e-c coupling was not affected.