bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigations of the Biology of Peranema trichophorum (Euglenineae)
Authors: Chen Y. T.
Published: April 2021

The feeding apparatus of Peranema trichophorum, consisting of cytostome and rodorgan, is independent of the reservoir system ; the latter is the same in structure and function as that of other Euglenineae. There are two flagella, one directed forward, the other backward and adherent to the ventral body surface. The anterior flagellum is longer and thicker than the adherent one. Both flagella are composed of a central core and an outer sheath. Electron micrographs suggest that the core consists of many longitudinal fibrils, and the sheath of many short fibrils radiating from the core, giving the whole flagellum the appearance of a test-tube brush. Treatment with certain proteindispersing agents cause the unfixed anterior flagellum to dissociate into three fibrils.

Peranema multiplies freely on a diet of living yeast-cells; dead yeast is not suitable. Euglena viridis, E. gracilis, and certain other unicellular algae can also serve as food. Egg-yolk, and especially milk, can be used to maintain bacteria-free pure cultures. Casein is suitable in combination with soil-extract or beef-extract, but never as good as milk. With the latter the individuals are larger and more numerous than with yeast as food, although the cultures decline earlier. Clear liquid media of many various kinds did not support growth : particulate food seems to be essential.

Peranema is capable of ingesting a great variety of living organisms provided these are motionless. Small organisms are swallowed whole ; larger ones are either engulfed or cut open by the rod-organ and their contents sucked out. The rod-organ can be protruded out of the cytostome and used in holding on to, and cutting, the periplast of the prey. Starch-grains, oil-droplets, and protein-particles are engulfed and digested. The main food reserves are paramylon-granules and oil-droplets.

H+ ions, decomposition products of proteins, and other substances diffusing out of living, and particularly dead, organisms attract gliding Peranema. Chemotaxis plays an important role in leading Peranema to its prey.

Both gliding and swimming have been observed in normal individuals, although the latter is less frequent. While there can be no doubt that swimming results from the action of the anterior flagellum, it does not seem to play an appreciable part in gliding. Nothing is known about the function of the adherent flagellum.
Methods for the Study of the Cytology of Bacteria and Pleuropneumonia-like Organisms
Authors: Klieneberger-Nobel Emmy
Published: April 2021

Methods for the demonstration of the various cytological elements of bacteria are described. The specialized techniques applicable to pleuropneumonia-like organisms and L-forms of bacteria are also presented.
The Autonomic Nervous System of the Chimaeroid Fish Hydrolagus colliei
Authors: Nicol Colin
Published: April 2021

The autonomic nervous system of the chimaeroid fish Hydrolagus colliei has been investigated by dissections and histological methods. It consists of a cranial parasympathetic portion and a sympathetic portion confined to the trunk. The latter extends from the level of the heart to the anus and consists of segmentally arranged ganglia on each side of the dorsal aorta. These ganglia are closely associated with small accumulations of suprarenal tissue. Two axillary bodies are the largest of the sympathetic and suprarenal structures. They lie about the subclavian arteries and are made up of a gastric ganglion and a relatively large mass of chromaffin tissue. The sympathetic ganglia lie in an irregular plexus of longitudinal and crossing sympathetic strands but there is no regular sympathetic chain or commissure between ganglia. There are white rami communicantes which connect the sympathetic ganglia with spinal nerves. A small pregastric ganglion lies on the rami communicantes to the gastric ganglion. The visceral nerves arising from the sympathetic ganglia proceed to blood-vessels, genital ducts, chromaffin tissue, and gut. The latter is supplied by large splanchnic nerves which originate in the gastric ganglia and proceed along the coeliac axis to the intestine, pancreas, and liver. Prevertebral ganglia are absent. A mucosal and a submucosal plexus are present in the intestine. The cranial component of the autonomic system comprises a midbrain and a hindbrain outflow. In the former there is a ciliary ganglion on the inferior oblique branch of the oculomotor nerve. Short ciliary nerves proceed from this branch to the eyeball. A radix longa is absent. Sensory fibres go directly to the eyeball from the profundus nerve as anterior and posterior long ciliary nerves. The hindbrain outflow comprises scattered nerve-cells and ganglia on post-trematic branches of the glossopharyngeal and vagus nerves. These autonomic fibres in the branchial nerves innervate smooth muscle in the pharyngeal region. A visceral branch of the vagus innervates the heart, oesophagus, and intestine; it also establishes a connexion with the pregastric ganglion. In general, the autonomic nervous system of Hydrolagus is very similar to that of selachians. It appears that the autonomic systems of these two groups have undergone little alteration since their origin in the Palaeozoic from some common form. Their autonomic systems reflect a simple and primitive level of organization from which more complex systems of the bony fishes and amphibians have evolved.
Determination of the Form of Regenerating Limbs in Asellus aquaticus
Authors: Needham A. E.
Published: April 2021

The nerve-supply to the regenerating anterior pleopods of Asellus aquaticus influences the rate of regeneration but not the character of the regenerate. The tissues of the locality of the blastema determine the character of the regenerate and also influence the rate and extent of regeneration. In contrast to the thoracic limbs these appendages are very sensitive to the induction of abnormalities of regeneration. The complete suppression of regeneration of a limb is the most common induced abnormality. An all- or-none effect i” evident. The development of supernumerary structures is the next most common abnormality. The re-emergence of the endopodite of the first pleopod, suppressed in normal ontogeny, is the most frequent supernumerary. It often shows homoeotic differentiation. A tendency towards bilateral symmetry is evident in all abnormalities, in spite of asymmetry in experimental treatment. Fusion of individual blastemae is not uncommon. There is no fusion with homoplastic embryonic tissue. There is no substance with the properties of a ‘wound hormone’. The regeneration of Pl. 2 in the male is more easily suppressed than that of Pl. i.
The Structure, Development, and Operation of the Hinge Ligament of Ostrea edulis
Authors: Trueman E. R.
Published: April 2021

The ligamental structure of Ostrea edulis is briefly described. The ligament is situated between the valves of the shell immediately below the urtibo and may be divided into two main layers, the outer and the inner, the principal features of which appear to correspond with those of other bivalves. The outer layer is divided into anterior and posterior halves by the inner layer, which occupies a central position. The axis (hinge or pivotal axis) about which the valves open is situated in the adult oyster along a line drawn through the outer layer and the upper part of the inner layer. When the valves are closed the ligament above this axis is subjected to a tensile strain and that portion below to compression, the forces so produced causing the opening of the valves. An attempt has been made to measure this force in relation to the surface area of the valves and it is found to be approximately 4·5 gm. mm./mm.2 This figure is comparable to those obtained when certain other species of bivalves are used. The ligament is shown to develop from the simple outer layer of the early larval stages, first by the addition of an inner layer and then by growth of this structure chiefly in a ventral direction. The initial dorsal region of the ligament soon degenerates and at the same time the pivotal axis moves ventrally between the valves, thus increasing in length. This method of growth is compared with that of an elongate external ligament and the mechanical implications are suggested.
A Comparative Study of the Chilopod and Diplopod Cuticle
Authors: Blower Gordon
Published: April 2021

The histology of the cuticle and epidermis of certain chilopods and diplopods is described. Two principal layers of the cuticle are recognized, an outer homogeneous and refractile exocuticle which is usually but not invariably pigmented and an inner endocuticle. The endocuticle and the exocuticle both contain chitin. The exocuticle is considered as a modification of the outer part of the chitinous matrix by an impregnating substance. Certain properties of the impregnating substance are described. It appears to be a substance rich in phenolic groups, perhaps a protein, which has a stability and resistance to acids in its own right irrespective of the presence of pigment or aromatic cross-links. Pro-sclerotin is suggested as a name for this substance. Chemical tests show that it is present in regions not optically definable as exocuticle. The epidermis is virtually an epithelium of gland cells which appear to secrete lipoid material. The lipoid passes on to the surface of the cuticle by means of ducts passing through the cuticle. Here it appears to form a superficial layer and to impregnate the sclerotin and pro-sclerotin. There appears to be an intimate association of lipoid with the aromatic groups of the pro-sclerotin and sclerotin. Destruction of the aromatic groups by means of an oxidizing agent appears to intensify the colouring of the lipoid by Sudan. The myriapod cuticle is shown to have many features in common with that of other arthropods. The main difficulty in the way of extensive homology with other arthropod types is the absence in myriapods of an outer non-chitinous and resistant layer.
The Specific Granules of the Pancreatic Islet Tissue of the Frog (Rana temporaria)
Authors: Barrington E. J. W.
Published: April 2021

An account is given of some characteristics of the pancreatic islet tissue of the frog, based largely on material fixed in Helly’s fluid and subsequently postchromed. It is shown that the cells, which superficially differ greatly amongst themselves in appearance, can be interpreted as representing stages in a single secretory cycle, and cannot be readily differentiated into the entirely distinct cell types which have commonly been thought to characterize the islet tissue of other vertebrates. Secretory activity centres round an organelle which is believed to be the true ‘specific granule’, and which is formed by the condensation of chromophil material within a chromophobe body. The latter develops a sudanophil rim which is also a characteristic feature of the specific granule itself, the secretory activity of the latter involving an intense lipoid metabolism and being accompanied by a reduction of chromophilia. These observations cannot at present be readily related to the traditional descriptions of the ‘A’ and ‘B’ (and more recently ‘D’) cells, although the specific granule in the earlier stages of its activity appears to resemble the ‘A’ granule of other vertebrates in its staining reactions. Certain reactions characteristic of ‘B’ and ‘D’ granules can also be recognized, but it is too early to evaluate these with confidence. The observations are discussed in the light of current views on the cell-inclusions, particular attention being drawn to the similarity which the chromophobe bodies bear to Golgi spheroids (lipochondria), both in their appearance and in their apparent ability to segregate material from the surrounding cytoplasm.
Studies on the Effect of Infection with Nosema apis on the Physiology of the Queen Honey-bee
Authors: Hassanein M. H.
Published: April 2021

When a queen honey-bee becomes infected with Nosema apis, the result can be very serious indeed for her colony. The metabolic processes are disturbed by the damage done by the parasite to the epithelial cells of the mid-gut, and this apparently leads to severe damage to the ovaries, at first by the production of a high proportion of eggs that fail to hatch, and ultimately by complete cessation of ov1-pqsition and supersession or death of the queen. In the case of Nosema bombycis, which attacks the silk moth, infection is carried from the female to her offspring via the egg; but there is no evidence that this ever occurs in the case of Nosema apis. Although large numbers of eggs, larvae, and pupae produced by infected queen honeybees were examined, none was found to be infected with any stage of Nosema apis.
The Activity of Amoebocytes and of Alkaline Phosphatases during the Regeneration of the Shell in the Snail, Helix aspersa
Authors: Wagge L. E.
Published: April 2021

Experiments show that in Helix aspera amoebocytes repair a damaged shell after transporting calcium carbonate and proteins from other parts of the shell, or from the digestive gland. The mantle is firmly applied to the damaged area and over it exudes fluid rich in amoebocytes. These secrete, and rapidly calcify, a protein membrane. Similar additional calcified membranes give firm protection after 24 hours.

The shell serves as a reservoir of calcium and protein, invaluable to a terrestrial gastropod. Amoebocytes can carry calcium back to the body. Extensive shell damage is repairable provided enough reserves remain: a snail cannot rebuild an entirely new shell. Thickening occurs whenever calcium and protein are available. Shell growth, however, initiated by the secretion of the periostracum, exclusively formed by the mantle skirt, happens only in conjunction with body growth.

Provided feeding activities are normal, alkaline phosphatases are abundant during shell repair, especially around digestive gland lime cells. Shell repair and digestion are closely associated. Amoebocytes, ineffective in an active, starved snail, can repeatedly repair damaged shell when a snail feeds, if only on filter paper: for once stimulated ample calcium and proteins are available for them in the shell.
Phenolic Tanning and Pigmentation of the Cuticle in Carcinus maenas
Authors: Krishnan G.
Published: April 2021

The histochemistry of the cuticle in different stages of the moult cycle of Carcinus maenas is described. The newly formed cuticle of a crab exposed at moulting shows evidence of phenolic tanning in the epicuticle. The subsequent tanning of the pigment layer of the endocuticle is confined to a brief period immediately after moulting. The polyphenol oxidase of the epicuticle involved in tanning disappears soon after moulting, but some time later an oxidase is again indicated, this time in the pigment layer. It appears to be secreted by the tegumental glands. From the concurrent appearance of a polyphenol oxidase and tyrosine and the subsequent formation of dihydroxyphenols and melanin-like substances in the cuticle, it is suggested that the oxidation products of tyrosine are responsible for the pigmentation of the cuticle. Pigmentation of the cuticle is discussed in relation to phenolic tanning in Crustacea and Insecta.
Intranuclear Birefringent Inclusions, an Artifact Occurring in Paraffin Sections
Authors: Nedzel G. A.
Published: April 2021

Intranuclear birefringent inclusions, apparently paraffin, are often observed in paraffin sections which are dehydrated in acetone instead of alcohol after staining. These inclusions are not removed by prolonged immersion of the sections in xylene or other fat solvents at room temperature. They may be removed from unmounted sections by clearing these sections in xylene after the usual hydration and alcohol dehydration, either before or after staining. They may be removed from resin-mounted sections, but not completely so, by warming the sections in an oven at 58° C. for 15 minutes.
On the Abdominal Appendages of Larvae of Trichoptera, Neuroptera, and Lepidoptera, and the Origins of Jointed Limbs
Authors: Pryor M. G. M.
Published: April 2021

The musculature of the abdominal appendages of the larvae of Sialis and Corydalus (Neuroptera) is described, and their homologies discussed. The terminal appendages of a primitive Trichopteran, Rhyacophila sp., correspond muscle’ by muscle with those of Corydalus. The terminal appendages of the larvae of typical members of other families of Trichoptera are compared with those of Rhyacophila-, although there is great variety of form, the same muscles can be traced in all. Similarities between the larvae of Neuroptera and Lepidoptera are not so close ; the resemblances are in general features which are shared with other soft blood-filled appendages such as those of Tardigrada or Onychophora. Finally the general mechanical principles governing the bending of limbs are discussed. Soft turgid appendages such as the abdominal legs of caterpillars depend on a mechanism quite unlike that of the hard, jointed limbs of other arthropods, and it is difficult to see how the one can have evolved from the other. It is suggested that a parallel evolution has taken place in the terminal appendages of Trichopteran larvae, and intermediate stages are described which suggest a way in which the change may have come about in true appendages.
The Blood-system in the Serpulimorpha (Annelida, Polychaeta) IV. Intravasal Tissues
Authors: Hanson Jean
Published: April 2021

Intravasal tissues of unknown function have been found in Pomatoceros triqueter, Vermiliopsis infundibulum, Protula intestinum, and Apomatus ampulliferus. They consist of connective tissue fibres clothed with small cells with densely staining cytoplasm. In Pomatoceros the tissue is situated intersegmentally in the gut sinus of the thorax and anterior part of the abdomen; it lies on each side of the sinus, and the ring vessels open into spaces within it. In Vermiliopsis the intravasal tissue fills the sinus in the posterior part of the abdomen. In Protula and Apomatus it is situated in swellings of specialized structure on the abdominal ring vessels close to the sinus. They closely resemble the ‘blood-glands’ of Pheretima (Stephenson, 1924). These intravasal tissues may correspond to the heart body which other annelids possess but serpulids and sabellids lack.
The Histochemical Demonstration of Keratin by Methods involving Selective Oxidation
Authors: Pearse A. G. Everson
Published: April 2021

Oxidation of tissues with performic acid gives rise to histochemically detectable reaction products particularly in two classes of material. These are keratin and lipoids of the phosphatide class. Three methods have been evolved for visualizing the effect of performic acid on cystine-containing structures; two of these (performic acid/Schiff and perfoimic acid/cobalt nitrate) also record the effect on lipoids. An attempt has been made to elucidate the chemistry of the reactions and it is suggested that oxidation of cystine in the tissues gives rise not only to cysteic acid (alanine-beta-sulphonic) but to another acid (alanine-beta-sulphinic). The latter is responsible for the positive reaction with Schiff’s solution. The Schiff reaction with performic acid oxidized lipoids is due to the formation of substances giving the reactions of aldehydes. It is possible that similar groups may be produced from lipoid molecules by periodic acid oxidation and that these and not polysaccharides (ri glycols) are responsible for the periodic acid-Schiff reaction in such cases.
The Cytosome of differentiating Cells in the Ovotestes of Slugs
Authors: Pelluet D. , Watts Anne H. G.
Published: April 2021

The distribution of ascorbic acid, alkaline phosphatase, and mitochondria has been followed during the differentiation of germinal epithelium cells into spermatogonia, oocytes, and nurse-cells in the ovotestes of slugs. All three substances appear in the cytoplasm of the oocyte and increase during its growth. Occasionally the oocyte nucleolus gives a positive test for ascorbic acid. The heads of the mature spermatozoa contain alkaline phosphatase. The cytoplasm of the germinal epithelium, spermatogonia, and spermatocytes occasionally gives’ a positive reaction for ascorbic acid. The development of the nurse-cells is accompanied by an increase in the size of the mitochondria. Attachment of the spermatids results in a decrease in size and number of the mitochondria in the nurse-cells. Alkaline phosphatase, ascorbic acid, and mitochondria show no significant change, either in form or quantity, in the indifferent cells of the ovotestis by which one could predict their destiny.
The Structure and Function of the Basement Membrane Muscle System in Amphiporus lactifloreus (Nemertea)
Authors: Cowey J. B.
Published: April 2021

The body wall of A. lactifloreus has the following structure from the outside inwards.

A basement membrane of five to six layers immediately underlying the epithelium. Each layer consists of right-hand and left-hand geodesic fibres making a lattice, whose constituent parallelograms have a side length of from 5 to 6μ. The fibres are attached to one another where they cross ; so there can be no slipping relative to one another. A layer of circular muscle-fibres running round the animal containing two systems of argyrophil fibres—one of fibres at intervals of 10μ. running parallel to the muscle-fibres and the other of fibres running radially through the layer from the basement membrane to the myoseptum. A myoseptum which is identical in structure with a single layer of the basement membrane. A layer of longitudinal muscle, whose fibres are arranged in layers on each side of a series of longitudinal radial membranes.

Membranes identical in structure with the basement membrane invest the nerve cords, the gut, the gonads, and the proboscis.

The interrelations of argyrophil and muscle-fibres in the muscle layers is described and their functioning discussed.

The system of inextensible geodesic fibres is analysed from a functional standpoint. The maximum volume enclosed by a cylindrical element (cross-section circular), of such a length that the geodesic makes one complete turn round it, varies with the value of the angle θ between the fibres and the longitudinal axis. When θ is o° the volume is zero; it increases to a maximum when θ is 54° 44’ and decreases again to zero when θ is 90°. The length of the element under these conditions varies from zero when θ is 90° to a maximum (the length of one turn of the geodesic) when θ is o°.

The body-volume of the worm is constant. Thus it has a maximum and minimum length when its cross-section is circular, and at any length between these values its cross-section becomes more or less elliptical. It is maximally elliptical when θis 54° 44’, i.e. when the volume the system could contain, at circular cross-section, is maximal. From measurements of the ratio of major to minor axes of this maximally elliptical cross-section, the maximum and minimum lengths of the worm relative to the relaxed length and values of θ at maximum and minimum length are calculated. The worm is actually unable to contract till its cross-section is circular; but measurements of its cross-sectional shape at the minimum length it can attain, permit calculation of the theoretical length and value of θ for this cross-sectional shape.

Calculated values of length and the angle θ agree well with the directly observed values.
On the Nutrition of Ochromonas
Authors: Pringsheim E. G.
Published: April 2021

A species of the chrysophycean genus Ochromonas from England was grown in pure culture and compared with similar strains isolated in the United States. Although these organisms possess chromatophores with chlorophyll, they need organic substances not only as a source of nitrogen compounds, but as independent carbon and energy sources; they also require certain growth factors. Peptones are better as nitrogen sources than single amino-acids, few of which give satisfactory results. The utilization of inorganic nitrogen could not be demonstrated. As carbon sources sugars, alcohols, and fats, and, to a lesser degree, acetate, are suitable. Growth factors contained in liver extract, milk and yeast autolysate, and in smaller amounts in most peptones, are indispensable. Enzymes hydrolyzing starch, sucrose, fat, and protein are excreted.

Ochromonas ingests and digests starch grains, casein, oil droplets, and small organisms. Neither bacteria nor yeast nor small algae were found able to support growth of any of the strains, even in the light. An additional carbon compound and possibly special vitamins are required. The hypothesis is put forward that phagotrophy chiefly serves for obtaining chemical compounds which the cell cannot synthesize itself and which have the character of vitamins. Phagotrophy therefore supplements the other means of nutrition, in the main qualitatively, while sugar, &c., supplement it quantitatively and are indeed indispensable.

The same media which support ample growth in the light do so also in the dark. This shows that photosynthesis is of little importance for the growth of the organisms, although it keeps them alive for long periods, while in the dark they soon die.

Correlated with the manifold ways of acquiring food, there is also a remarkable variability in the size and shape of the cells, and still more in the dimensions and pigmentation of the chromatophores, and in the reserves stored as leucosin, volutin, and oil. These features which now prove to depend so much on conditions have previously been widely used in the diagnosis of species. The basis of classification should therefore be revised. Apart from the stigma, which is specific, use ought to be made only of those characters whose variation with conditions is reasonably well known.

The extraordinary nutritional versatility of Ochromonas is considered to be a primitive character. From ancestors with a mixed nutritional habit, phototrophic, phagotrophic, and saprotrophic flagellates seem to have evolved, each with only one of the three modes of nutrition that are combined in Ochromonas.
The Effects of Single Doses of Pilocarpine and of Histamine upon the Granules of Oxyntic Cells of Rats, with Special Reference to their Phospholipine Content
Authors: Menzies Gordon
Published: April 2021

New data are presented on the morphology and cytochemistry of the granules of the oxyntic cells of the rat’s stomach in continuation of work previously reported (Menzies, 1949). The effects of single injections of pilocarpine and of histamine on the granules were investigated, with particular reference to their phospholipine content as shown by Baker’s acid haematein method. Pilocarpine causes a marked enlargement of the granules with loss of phospholipine from the central part of many of the larger granules, and complete loss of phospholipine from others. The granules that have lost their phospholipine probably still contain lipoid as shown by sudan black. Pilocarpine also causes marked aggregation of the granules. Histamine causes a less marked increase in granule size and no observable loss of phospholipine, but some of the granules became elongated, an effect that can be seen with the phase-contrast microscope, and there is a tendency for them to recede to the peripheral parts of the cells associated with an enlargement of the intracellular canals. Both pilocarpine and histamine result in some enlargement of the oxyntic cells, the effect being more marked with pilocarpine. Neither pilocarpine nor histamine alters the size or shape of the non-lipoid moiety of the granules. Supravital colouring with neutral red shows a few droplets in oxyntic cells in the bases of the gastric glands. These enlarge slightly after histamine and greatly after pilocarpine, and they are always spherical. It has not yet been possible to decide as to their exact nature.
Experiments with P32 and I131 on Species of Helix, Arion, and Agriolimax
Authors: Fretter Vera
Published: April 2021

If Helix aspersa, H. pomatia, Arion hortensis, and Agriolimax agrestis be fed on a diet which contains P32, autoradiographs show that the isotope is taken up by the digestive and lime cells of the digestive gland. From the formermost of it passes to the haemocoel, though some is retained for immediate metabolic activities ; in the lime cells it is stored in calcium spherules. A very small amount of the tracer enters the body through the wall of the oesophagus, and more through the intestine, this site of diffusion being most pronounced directly after hibernation.

The P32 in the haemocoel is dispersed to all tissues : all of them take up a little ; in some it becomes concentrated. Concentrations appear in the nerve ring, the mucous and salivary glands, the odontophore and certain cells of the mantle.

In the nervous system deposits are heavy around the fibres and slight in the cytoplasm of the cells ; they indicate a compound, soluble in alcohol, which may be phos-pholipine, associated with medullated nerves.

The phosphorus in mucous cells, most pronounced in the pedal and salivary glands, may be combined with the calcium which stabilizes mucus and prevents its rapid dispersal.

The incorporation of isotope into the developing tooth of the radula indicates the relative activity of the basoblasts and cuspidoblasts : in early development of a tooth the basoblast secretes more actively, but as it becomes effete secretion by the cuspidor-blast is accelerated. When the tooth is liberated from the latter there is no further addition to its substance.

Phosphorus deposits in the mantle are in the calcium cells which secrete the shell. Here, as in the lime cells, and around certain blood-vessels, excess may be stored as calcium phosphate ; reserves in the digestive gland are the largest.

Amoebocytes concerned with the regeneration of the shell of Helix pomatia and H. aspersa carry the tracer element, and some of it is deposited in the shell. Also in the slug the tracer is transported by amoebocytes.

Radioactive iodine in the lumen of the gut is taken up most readily by digestive cells ; some enters the lime cells. Only in sparing quantities does this isotope pass from the gland to the rest of the body, and this entry is presumably associated with ionic exchange. It is not accumulated in any cell, except in the kidney whence it is excreted ; it leaves the digestive cells to pass from the body with the faeces.
Phosphomonoesterase Content and Localization in the Meso-and Metanephros of the Chick Embryo
Authors: Junqueira L. C. U.
Published: April 2021

Chemical determinations were made of the alkaline and acid phosphatase content of meso-and metanephros of chick embryos between 4 days of incubation and 6 days after hatching. Histochemical localization of alkaline phosphatase and of ribonucleaseremovable basiphilia was also studied in these organs.

A study of the data obtained suggest the following conclusions : The acid and alkaline phosphatase activity of the mesonephros increases from the 4th to the 16th day, decreasing from then onwards.The acid and alkaline phosphatase activity of the metanephros increases from the 11 th to the 16th day, decreasing slowly to the 20th day. A rapid rise is observed after hatching.The alkaline phosphatase activity that is diffusely located in the cells of recently formed secretory tubules of the meso-and metanephros polarizes to the brush border zone later on.Ribonuclease-removable basiphilia, abundant in the mesonephric tubules up to the 6th day of incubation, decreases from then onwards.The metanephric blastema and tubules present a high concentration of ribonuclease-removable basiphilia up to the 13th day. From then on its content decreases in the whole organ with the exception of certain groups of cells still in differentiation.

The possible correlation between these findings and meso-and metanephros differentiation and function is discussed.
Mounting Collodion Sections before Staining
Authors: Richardson K. C.
Published: April 2021

In the standard textbooks on microscopical technique many ways are quoted for attaching collodion sections to slides before staining. With some of these methods the attachment is so precarious that extra care is needed during the manipulations of staining and dehydration : with others the section is covered with a film of collodion or stuck to a layer of gelatine. Such supporting films, however, often take up some of the stain. The method to be described is simple and reliable and can be applied to all types of collodion technique, ranging from thin sections cut in collodion-paraffin or low viscosity nitrocellulose, to the large, thick sections commonly cut from collodion blocks hardened by evaporation or chloroform and stored in alcohol. In each case it is possible to remove the collodion immediately after mounting so that the section becomes comparable with a routine paraffin section, and will withstand prolonged treatment even in hot solutions without becoming detached.
Observations concerning the Specificity of the Acid Haematein Test for Phospholipines
Authors: Casselman W. G. Bruce , George O. T.
Published: April 2021

Studies with synthetic enantiomeric a-phosphatidic acids, a-phospholipines, and related compounds, and with highly purified, natural lipine fractions confirm that Baker’s ‘acid haematein test (controlled by the pyridine extraction test) is a method for the histochemical recognition not of lipine in general, but of phospholipine’. A true positive reaction is also given by certain phosphatidic acids.
Histochemical Distribution of 5-Nucleotidase in Snake Tissues: Presence of 5-Nucleotidase and Absence of Alkaline Phosphomonoesterase in Venom Glands of the Rattlesnake
Authors: Bragdon D. E. , Mcmanus J. F. A.
Published: April 2021

Activity of the specific alkaline phosphatase, 5-nucleotidase, is intense in the epithelium and secretion of the rattlesnake venom gland. Non-specific alkaline phosphatase activity is lacking. Thyroid epithelium, the smooth muscle of great vessels, and (inconstantly) smooth muscle of abdominal hollow viscera show greater 5-nucleotidase than nonspecific activity. These findings confirm the specificity of 5-nucleotidase.
Cell Shrinkage caused by Fixatives and Paraffin-wax Embedding in Ordinary Cytological Preparations
Authors: Ross K. F. A.
Published: April 2021

A series of measurements was made of the diameters of the cells and nuclei of the primary spermatocytes of the snail Helix aspersa in preparations made by embedding in paraffin wax after fixation in a number of different cytological fixatives. These were compared with similar measurements made on the living spermatocytes mounted in suitable saline solutions, and the shrinkage that the cells underwent as a result of fixation and embedding in each case was calculated from the medians of the size-distributions recorded.

The results showed that the amount of shrinkage varies to some extent according to the fixative employed—picric acid gave the greatest linear cell-shrinkage (about 40 per cent.) and Sanfelice’s fluid by far the least (about 13 per cent.); but with this one exception the differences in final cell-size were not very great, and represent a linear shrinkage to about 67 per cent, and a volume shrinkage to about 30 per cent, of the original dimensions of both cell and nucleus.
The Golgi Apparatus and Lipoidal Bodies in Exocrine and Endocrine Cells in the Pancreas of Man
Authors: Lacy Dennis
Published: April 2021

The cells of the pancreas of a woman were studied by means of Aoyama’s and Baker’s methods with the following results:

A canal-like Golgi apparatus and lipoidal bodies are observed in both exocrine and endocrine cells. The size of the apparatus and the number of lipoidal bodies are in inverse ratio in both cell types.

These results do not support the theory that the Golgi apparatus as seen in fixed cells is the result of the metallic impregnation of lipoidal bodies.
Metachromatic Dye-Substrate Interactions
Authors: Sylvan Bengt
Published: April 2021

From the interactions between azure A and various substrates with different physical and chemical characteristics, some suggestions are made as to the nature of the metachromatic colour reaction. The following essential factors are necessary for the appearance of metachromasia.

The orderly alignment of dye molecules is favoured if the molecules present hydrophobic and hydrophilic parts. The distribution of electro-negative surface charges of the substrate determines the alignment of dye molecules and the degree of metachromasia. A certain minimum intercharge distance (interplanar), possibly about 5 A, is a prerequisite for metachromasia. The degree of metachromasia increases when the intermolecular distance between adjacent dye molecules aggregated to the substrate surface becomes less than 5 A. The presence of water is essential for metachromatic interaction.

The observed spectral absorption shifts are explained by the assumption that new bonds appear between adjacent dye molecules. The necessary energy requirements are of the order of about 8 cal./mol. In the case of azure A, various types of intermolecular bonds are discussed: hydrogen bonds or perhaps hydrogen bonds plus oxygen-sulphur bridges. It seems very likely that water molecules may be intercalated between adjacent dye molecules as suggested by Scheibe and Sheppard.

Since the dye and many organic substrates form polydisperse colloidal solutions and since further the dye-substrate interactions often imply the appearance of micellar aggregates and precipitates in in vitro experiments, spectrophotometric data should be interpreted with great caution. Evidence is presented indicating that the heterogeneity of the sol systems in many instances renders spectrophotometry useless. The desired colour changes are instead conveniently registered by microscopy with transmitted light.

Available data indicate that the electro-negative surface charge density is the essential characteristic of the various substrates for the conditioning of metachromatic dye-substrate interaction.
The Value of ‘Spreading Factors’ in the Demonstration of Tissue Neural Elements
Authors: Weddell G. , Pallie W.
Published: April 2021

A description is given of the value of ‘spreading factor’ (hyaluronidase) used in conjunction with various neurohistological methods for the display of tissue neural elements. It has been shown that after its use nerve fibres and their terminals in a variety of tissues, including the cornea, closely resemble those seen in fresh specimens of cornea under phase-contrast conditions. The specimens prepared after treatment with hyaluronidase are almost free from artifacts. The staining or impregnation process can be controlled with certainty and precision to produce evenly stained specimens in the tissues we have used. It is suggested that some tissues may need special treatment to obtain optimal results. The use of ‘spreading factor’ makes it possible to determine the cause of the artifacts commonly observed after employing standard neurohistological techniques. The rationale of using ‘spreading factor’ in conjunction with neurohistological techniques is discussed.
A Micro-injection System
Authors: Worst J.
Published: April 2021

The apparatus works by the thermal expansion of water. The water is contained in a fine, thick-walled capillary tube, one end of which is made into a micro-pipette. The other extremity, which is closed, is heated over varying lengths by warm water in order to obtain the required change in the volume of the water by thermal expansion.
Relations between Metachronism and the direction of ciliary beat in metazoa
Authors: Knight-Jones E. W.
Published: April 2021

In various ciliated epithelia one can distinguish either symplectic, antiplectic, dexio-plectic, or laeoplectic metachronal waves, according to whether the effective beat of their cilia is with, against, to the right of, or to the left of, the direction of movement of the waves. In a given epithelium the relation between the direction of the waves and the direction of beat is constant.

Symplectic waves are probably associated with the transport of large particles, or viscous masses of mucus; antiplectic and diaplectic waves are better suited for creating water currents. It is unusual to find both dexioplectic and laeoplectic waves in the same animal; indeed, it is the rule for only one of these two types of metachronism to occur throughout a given systematic group. Dexioplectic waves are found in Protochordata, primitive Spiralia, the velum of Eulamellibranchiata, Phoronidea, Brachiopoda, Bdelloidea, and Melicertida; laeoplectic waves are found in Chaetopterus, Mollusca generally, Bryozoa, and Ploima. The incidence of dexioplectic and laeoplectic meta-chronism is not influenced by morphological reversals of symmetry such as the situs inversus. The relation between the direction of beat and the direction of the waves is therefore probably determined by cytological or stereochemical factors, rather than by gross morphology.
Lipo-Protein Cells in the Blood of Carcinus Maenas, and their Cycle of Activity Correlated with the Moult
Authors: SEWELL M. T.
Published: April 2021

A description is given of cells termed lipo-protein cells in the blood of Carcinus maenas, and of their development from amoebocytes. These cells exhibit a marked cycle of appearance and disappearance correlated with the moult. They appear towards the end of the instar, reach their maximum development immediately before the epicuticle of the new cuticle is secreted, and disappear soon after the moult. They show positive reactions for the presence of lipids, aromatic substances, tyrosine, and peptide linkages. As the epicuticle and pre-exuvial endocuticle are secreted, the colouring with Sudan black B and the Millon reaction in the cells decrease in intensity. The cells are believed to synthesize lipo-protein or extract it from the haemolymph, and to transport it to the epidermis and thence to the developing cuticle, thus contributing to the secretion of the epicuticle and impregnating the pre-exuvial endocuticle. The lipo-protein cells are compared with the oenocytes of insects and with the granulocytes and vacuolar cells or leberidocytes of spiders.
Experiments on the Mechanism of Silver Staining: Part I. Impregnation
Authors: Peters A.
Published: April 2021

In the impregnating stage of silver staining, there are essentially two different reactions taking place between the silver ions and the sections of fixed tissue. A sub-stantial part of the silver is combined with the tissue in the unreduced form, and a smaller part is reduced to produce silver nuclei which form centres on which the de-veloping agents can deposit additional silver derived from the combined (reducible) silver fraction.

A study of the effect of pH and time of impregnation, as well as of the specific blocking of chemically active protein end-groups upon the reducible silver fraction, suggests that this is chiefly combined with histidine and that it is not limited to the sites of the final differential staining. Except for the cell nuclei, the reducible silver shows a uniform distribution throughout the section; the amount taken up is in equilibrium with the silver ion concentration in the impregnating bath.

The fraction present as silver nuclei increases progressively with time, with in-creasing pH, and with the temperature of the impregnating bath. Silver ions appear to be converted to silver nuclei by a process of physical reduction, and once formed, the nuclei are quite stable.

Deposition of silver nuclei, necessary for differentiation of the stain, only occurs after impregnation between pH 7·5 and 9·0. In addition, it is only within this range that a sufficient amount of reducible silver is taken up to produce deep staining after development.
The Transition to Air Breathing in Fishes
Authors: Graham Jeffrey B.
Published: April 2021

The armoured catfish, Ancistrus chagresi, is a facultative air breather and uses its stomach as an air-breathing organ (ABO). Comparisons of control fish and fish that had become acclimated to hypoxia and air breathing for 14–21 days were carried out to assess the effects of this treatment on bimodal (aerial and aquatic) gas exchange capacity. Hypoxia acclimation elicits physiological and biochemical changes that enable A. chagresi to increase O2 utilization both by its gills in hypoxic water and by its ABO. Compared with control fish, hypoxia-acclimated Ancistrus have a higher blood-O2 affinity and more haemoglobin (Hb) and can maintain a higher aquatic oxygen consumption rate in hypoxic water. They also have a 25 % larger ABO volume, are able to hold each air breath longer, and can reduce ABO O2 partial pressure to a lower level. In both groups, respiratory CO2-release occurs primarily through the gills. An air breath instantly causes tachycardia and a reduction in the frequency and amplitude of branchial ventilation. Their lower cardiac and gill ventilation rates in hypoxia and during air breathing suggest that hypoxia-acclimated fish are more adapted for hypoxia than are control fish. During the period an air breath is held in the ABO, hypoxia-acclimated fish exhibit more coordinated phase shifts in gill ventilation and cardiac rates. These may favour an initial phase of efficient aerial O2 uptake from the ABO and transport through the body followed by a period of aquatic CO2 release from the gills.
Prey Capture Hydrodynamics in Fishes: Experimental Tests of Two Models
Authors: Lauder George V.
Published: April 2021

Three experimental modifications of the feeding mechanism in the bluegill sunfish (Lepomis macrochirus Rafinesque: Centrarchidae) were performed to distinguish between two alternative hydrodynamic models of the high-speed suction-feeding process in fishes. These two models make different predictions about the change in slope of the regression line representing the relationship between buccal and opercular cavity pressures, and the three experiments provide a critical test of the models. The results from all three tests unequivocally support (1) the concept of the gill bars as a resistant element within the mouth cavity functionally dividing it into buccal and opercular cavities, (2) the negligible role of lateral movement of the gill cover (operculum) in generating negative mouth cavity pressures, and (3) the large pressure differentials previously reported between the buccal and opercular cavities. Measured pressures conform neither in relative magnitude nor waveform with pressures predicted from theoretical mathematical models. Inertial effects and accelerational flows are key aspects of high-speed suction feeding.
Swimming and Diving in Tufted Ducks, Aythya Fuligula, with Particular Reference to Heart Rate and Gas Exchange
Authors: Woakes A. J. , Butler P. J.
Published: April 2021

In six tufted ducks there was a linear relationship between heart rate and oxygen consumption when swimming at different velocities. Mean oxygen consumption at mean duration of voluntary dives was 3·5 times resting and not significantly different from that at maximum sustainable swimming speed. Contrary to an earlier report (Prange & Schmidt-Nielsen, 1970), leg beat frequency increased with increased swimming speed.

Although heart rate at mean dive duration was 51% higher than the resting value, it was a significant 59 beats min−1 lower than predicted from the heart rate/oxygen consumption relationship obtained during swimming. This relationship is, therefore, of no use for predicting oxygen consumption from heart rate during diving, nor incidentally during transient changes during air breathing.

It is concluded that during voluntary diving in tufted ducks there is a balance between the cardiovascular responses to forced submersion (bradycardia, selective vasoconstriction) and to exercise in air (tachycardia and vasodilatation in active muscles), with the bias towards the latter.