bluuebunny/crossref_metadata_2025_split huggingface dataset:
On Some Freshwater Rhizopoua, New or Little-known.
Authors: Archer William 
Published: April 2021

ABSTRACT
The microscopist, in the course of his examination of his gatherings made from pools and ditches, be the objects of his research what they may, cannot fail to encounter certain ordinary representatives of the group, to some new or little- known forms of which, I am, in the following communication, very cursorily about to draw attention ; and this, indeed, rather by hardly more than simply pointing to the figures, than by assuming to throw upon them an additional light by any special observations.
An Examination of the Cuticles of two Scorpions, Pandinus imperator and Scorpiops hardwickii
Authors: Kennaugh J. 
Published: April 2021

ABSTRACT
The cuticles of Pandinus imperator and Scorpiops hardwickii have been examined histologically and histochemically. They consist of a two-layered epicuticle, a hyaline exocuticle, a quinone-tanned exocuticle, an impregnated but untanned exocuticle, and on the inner surface an unmodified procuticle. The hyaline exocuticle is, however, single in Scorpiops and double in Pandinus. With the exception of the hyaline exocuticle the cuticles therefore conform to the basic arthropod pattern.
The quinone-tanned exocuticle closely corresponds with that of insects but the hyaline exocuticle seems to have no counterpart in other arthropods. The sulphur content of the cuticle has been determined and it is probable that sulphur is present only in the hyaline exocuticle.
The statement by Krishnan that chitin is present in the epicuticle is critically examined and a possible explanation of the differences which have been reported between the cuticles of different scorpions is offered.
The Iron-containing Shell of Gromia oviformis (Rhizopoda)
Authors: Hedley R. H. 
Published: April 2021

ABSTRACT
Gromia oviformis has an organic shell or wall modified at one point to form a specialized oral region through which the protoplasm extrudes as pseudopodia. Whereas the shell appears to be predominantly proteinaceous with additional acid mucopolysaccharide and lipid components, the gel-like oral capsule, the main feature of the oral region, appears to be composed mainly of acid mucopolysaccharide.
The changes in form undergone by the oral capsule during the opening and closing of the oral region are described.
The shell, apart from the oral capsule, normally contains a large amount of ferric iron. When sections, from which the iron had been removed, were immersed in seawater reinforced with iron or in aqueous iron solutions, it was found that iron was only taken up by the shell when the concentration was greater than 12·5 mg Fe per litre. Only when the concentration was in the region of 200 mg Fe per-litre did the shell take up an amount comparable with that which is normally present. It appears unlikely that during life a reaction between the iron in normal sea-water and the shell can be wholly responsible for the iron content of the organic wall. Alternative sources of iron are discussed.
A great reduction in the amount of iron taken up from iron solutions under conditions of low pH, and after the sections have been methylated, points to the importance of carboxyl groups in the binding of iron by the shell. The nature of the union of the iron with the wall is discussed and shown to be similar in some ways to that in leather tanning processes where inorganic tanning agents are employed.
The Test of the Ascidian, Phallusia mammillata
Authors: Endean R. 
Published: April 2021

ABSTRACT
A mucopolysaccharide, readily removed by mild acid hydrolysis, is associated with cellulose in the test of Phallusia mammillata (Cuvier). The mucopolysaccharide is produced in the vacuolated cytoplasm of epidermal cells covering the blood-vessels of the test.
The cellulose of the test appears to be produced by vanadocytes which have migrated into the test matrix through the walls of the test blood-vessels. In the test, the vanadocytes lose their acid and intraglobular osmiophil material and produce processes which extend into the surrounding test matrix. Minute globules and submicroscopic vesicles are present in the cytoplasm surrounding the large polysaccharide-containing globules of such vanadocytes, and also in the processes arising from such cells. The small globules and vesicles appear to arise from the large globules and to be involved in the production of micro-fibrils observed in electron micrographs of the test. The micro-fibrils, which vary from 20 to 40 m/x in diameter and are arranged in the form of an open network, may constitute a cellulose framework within the test.
An area devoid of test matrix occurs usually near each disintegrating vanadocyte. The remnants of each vanadocyte often come to lie in such an area. Capsules—the so-called ‘bladder cells’ of the test are thereby formed.
Phagocytes occur throughout the test and melanin-containing pigment cells are aggregated around its periphery.
The Structure and Function of the Cutaneous Glands in Helix aspersa
Authors: Campion Mary 
Published: April 2021

ABSTRACT
The glands discharging ‘slime’ on to the surface of the mantle collar and foot of Helix aspersa have been investigated histologically and histochemically on chemically fixed and frozen-dried material.
All the glands are unicellular; they lie in the connective tissue and discharge by pores passing between the epidermal cells; some are club-shaped, others are polygonal with a distinct and usually long duct. At least 8 different kinds of gland are found: 4 extruding various kinds of mucus, one protein, one calcium carbonate granules, one a pigmented secretion containing a flavone, and one releasing fatglobules. The histology of the mantle collar is very similar to that of the dorsal and lateral surfaces of the foot except that the glands in the mantle are usually larger.
All kinds of secretion are extruded from these parts. The glands of the sole of the foot are mostly of a distinct kind and produce mucus combined with protein.
The mechanism of discharge is discussed: some of the gland cells are enclosed in a network of muscle-fibres which are thought to be concerned in the removal of the secretion, in other cases no fibres have been found and it seems likely that changes in pressure in the haemocoel are involved.
The composition of the slime changes from colourless and viscous to yellow and watery when the animal is irritated. It is usually slightly alkaline, is not distasteful to man, and does not inhibit the growth of micro-organisms. The mucous component acts as a lubricant, and on the sole for adhesion. The calcium carbonate granules and the protein may be concerned in defence, while the flavone is a waste-product varying with the amount of green food eaten.
The epiphragm is formed by the secretion of part of the mantle collar and is probably dissolved away by a protein-splitting enzyme which has been demonstrated in the slime.
An electron microscope study of the tegument and associated structures of Dipylidium Caninum
Authors: Threadgold L. T. 
Published: April 2021

ABSTRACT
The ultrastructure of the ‘cuticle’ of Dipylidium caninum is described. The presence of mitochondria within the ‘cuticle’ and the connexion between it and subcuticular cells indicates that the outer covering of this cestode is of living cells forming an epidermis. On its external surface the epidermis is folded into finger-like micro-thriches and its thickness is pierced in places by pore-canals ending at the basement membrane. The sunken epidermal cells contain mitochondria, endoplasmic reticulum, fatty or glycogen inclusions, and protein crystalloids. It is suggested that such cells act as both storage and synthesizing units.
The possible bearing of the present morphological findings on cestode physiology is discussed, especially in reference to cestode resistance to digestion and the ability of the ‘cuticle’ to absorb.
The demonstration of lysosomes by the controlled temperature freezing-sectioning method
Authors: Bitensky Lucille 
Published: April 2021

ABSTRACT
Lysosomes, as isolated and defined by biochemists, are particles in which acid lytic enzymes are contained by a lipoprotein membrane; they are inert until the membrane has been rendered permeable. Previously it has not been possible to demonstrate cyto-chemically organelles which meet all these criteria, since all the preparatory procedures have affected the membrane permeability. The controlled temperature freezingsectioning method has permitted the demonstration of granules which are inactive for acid phosphatase until subjected to agents that will disrupt lipid-protein structures, such as heat, formalin, and ‘triton X-100’. Hence such organelles may be identified with the biochemists’ lysosomes.
Studies on the receptors in the cerebral vesicle of the ascidian tadpole, I. The otolith
Authors: Dilly P. N. 
Published: April 2021

ABSTRACT
Electron microscope observations of the gravity receptor of the tadpole larva of Ciona intestinalis show that the otolith is unicellular. The nucleus of the otolith persists for the entire life of the tadpole. The pigment mass of the otolith is intracellular, and it appears to be built up by fusion of granules. The otolith cell has a free part within the cavity of the cerebral vesicle, and a foot part which is contained within a mound of cells on the ventral wall of the cerebral vesicle. The junction between these two parts is probably the transducer region.
The transducer region is a complex system of folded cell membrane. Distortion of this system during rotation of the tadpole while swimming probably evokes changes in the neurones which surround the foot process of the otolith cell. One of these neurones is connected to the cerebral ganglion by a process which may be an axon. Fibrils extend from the transducer region of the otolith cell to the basement membrane, and probably serve to resist distortion of the transducer region.
The foot process of the otolith cell is connected to the surrounding cells by specializations of the cell membrane similar to attachment plaques.
The observations suggest that the otolith has been evolved from a cilium.
A note on the fine structure of a spirochaete
Authors: Grimstone A. V. 
Published: April 2021

ABSTRACT
A description is given, based on high-resolution electron micrographs of thin sections, of the structure of a spirochaete from the gut of a cockroach, Cryptocercus punctulatus. There is a central cell-body, the structure of which resembles that of a bacterium. Two kinds of granule are abundant in the cell-body: large ones, 150 to 250 Å in diameter, of unknown composition, and small ones, identified as ribosomes, which may be arranged in whorls on the inner surface of the bounding membrane. Numerous small chromatin bodies are present. The bounding membrane of the cell-body is complex in structure. The cell-body is loosely enveloped by a sheath, made up of a thin membrane supporting a coarsely filamentous outer layer. In the space between sheath and cell-body is a loose bundle of 60 to 100 fibres. These are 140 Å in diameter and are coiled helically around the cell-body. They resemble bacterial flagella and are thought to be responsible for the movements of the organism.
The fine structure of the respiratory tree in Cucumaria
Authors: Doyle William L. , Frances Mcniell G. 
Published: April 2021

ABSTRACT
The delicate tubules of the respiratory tree consist of 4 layers: a lining epithelium, a thick mucoid layer containing collagenous filaments, a smooth muscle net, and a coelomic epithelium. The free surfaces of both epithelia have well developed plasmodesms. Amoebocytes are present in all layers and the spherules of one type are considered to be precursors of the mucoid substance; another amoebocyte may be a fibroblast. Perpendicularly oriented smooth muscle fibres, as well as those parallel to each other, are linked by desmosomes ensuring synchronous contraction. Secretory activity is evident in distended cisternae of the endoplasmic reticulum of certain epithelial cells and in the vacuoles of the lining epithelium.
The fine structure of the cyst wall of the metacercaria of Fasciola hepática
Authors: Dixon K. E. , Mercer E. H. 
Published: April 2021

ABSTRACT
Observations with the electron microscope have shown that 4 major layers can be distinguished in the cyst wall : an outer tanned-protein layer, consisting of a meshwork of irregular bodies made up of cigar-shaped particles ;a predominantly mucopolysaccharide, finely-fibrous layer, closely adherent to the tanned layer;an inner, mainly mucopolysaccharide layer, which can be resolved into two layers differing in fine texture ;a dense, compact layer, composed of numerous protein sheets stabilized by disulphide linkages. This layer is formed from tightly wound scrolls, developed in intracellular vacuoles, which are unrolled at the surface of the animal after secretion.
The behaviour of tissue slices in chromate solutions: a study of the comparative importance of the tonicity and osmotic concentration of fixative systems
Authors: Bernard George R. , Wynn Gail G. 
Published: April 2021

ABSTRACT
A study was made of the weight changes undergone by slices of rat liver, kidney, and other organs immersed in certain fixatives containing chromium. In some experiments the data could be interpreted as indirect measurements of the fixative’s ‘effective’ osmotic pressure, or ‘tonicity’, a property which usually differs from the fluid’s ‘total’ osmotic pressure. In the case of kidney slices exposed to aqueous potassium dichromate, the rapidly occurring and reproducible responses seem proportional to the fixative concentration; no clear-cut differences were observed with liver slices similarly exposed. Altering the concentration of chromic acid did not affect quantitatively or qualitatively the response patterns of either tissue. Responses of slices to combinations of dichromate and formalin suggest cumulative action of the two moieties. The response patterns to the latter fluids could be modified by the addition of ‘indifferent’ substances such as sucrose.
The cytochemical localization of alkaline phosphatase in the testicular nephridia of the Indian leech, Hirudinaria granulosa, with special reference to the inner lobe
Authors: Dev Bhoomittra 
Published: April 2021

ABSTRACT
Previous studies by the author have revealed the intense localization of alkaline phosphatase in the initial-lobe cells and in the intracellular central canal on its first ‘round’ in the testicular nephridia of Hirudinaria granulosa. The present work throws light, for the first time, on the detailed cytochemical localization of the enzyme in the region where these two components communicate with each other. Openings of the central canal into an inner-lobe cell and of the latter into an initial-lobe cell have been noticed at one and the same level. An enzymatically negative inner-lobe cell serves as a bridge between the two positive zones. The bridge is, however, rarely observed because of the tendency to direct coalescence between the two enzymatically positive parts. The initial lobe sometimes opens into the central canal by means of more than one aperture. After the opening of the initial lobe into the central canal, the latter loses its enzymatic activity, and the radially arranged tubular inner-lobe cells disappear. The enzymatic activity in the peripheral cytoplasm of the intracellular central canal is usually more intense towards the point of its union with the initial lobe. The functional significance of the findings is discussed. Evidence for the concentration of the enzyme round the nucleus and in the nucleolus has also been noticed in the nephridial cells.
Spittle-production and tube-building by cercopoid nymphs (Homoptera). 3. The cytology and function of the fibril zone of the Malpighian tubules of tube-building nymphs
Authors: Marshall A. T. 
Published: April 2021

ABSTRACT
In tube-building nymphs, the proximal segments of the nymphal Malpighian tubules consist of two secretory zones, an anterior fibril zone and a posterior granule zone. This fibril zone clearly corresponds in position to (and is possibly homologous with) the anterior part of the proximal segment of the Malpighian tubules of spittlebug nymphs.
The cells of the fibril zone contain numerous stacked mucofibrils which are periodically extruded into the tubule lumen. Slight cytoplasmic vacuolation occurs immediately before and during extrusion. The extruded mucofibrils are passed down the hindgut and out to the exterior through the anus. The mucofibrils form an essential component of the nymphal dwelling tube and are laid down by characteristic movements of the abdominal tip.
The tube-building cercopoids (Homoptera, super-family Cercopoidea, family Machaerotidae) are divisible into two subfamilies, Enderleiniinae and Machaerotinae, of which the former is probably the more primitive (Maa, 1963)·
Nymphs of the tube-building cercopoids construct conical dwelling tubes on the stems of their host plants (Ratte, 1884; Maki, 1914; Hacker, 1922; Evans, 1940; Maa, 1963). The mode of formation of the dwelling tubes does not appear to have been previously reported and forms the subject of the present investigation.
Morphogenesis of the residual body of the mouse testis
Authors: Firlit Casimir F. , Davis Joseph R. 
Published: April 2021

ABSTRACT
A histochemical study of the detached cytoplasm of the maturing spermatid has been carried out. The detached cytoplasm has been designated as the cytoplasmic body and 4 distinct phases in its morphogenesis have been reported. The cytoplasmic tag of stage 11 of spermiogenesis has been designated as phase CB-1 in the morphogenesis of the cytoplasmic body. It was found to contain numerous granules of RNA, polysaccharides, and lipid. During phase CB-2 and CB-3, coalescence and fusion of these granules occurs, which result in a centrally-oriented plaque of RNA and glycogen, peripheral satellites containing polysaccharides, and large globules of lipid. During phase CB-4, the cytoplasmic body membrane becomes approximated to the plaque and at this stage of development the cytoplasmic body can be compared to the ‘residual bodies’ of Regaud. Peripheral migration towards the basement membrane of the seminiferous tubule now occurs. Some of the residual bodies undergo phagocytosis by Sertoli cells, while others eventually occupy a position at the level of the spermatogonia.
The organization and replacement of the epidermis in acoelous turbellarians
Authors: Dorey A. E. 
Published: April 2021

ABSTRACT
Five species of acoelous turbellarians have been studied: Convoluta roscoffensis Graff, C. convoluta (Abildgaard), Aphanostoma diversicolor Oersted, Otocelis rubropunctata (Schmidt), and Avagina incola Leiper. A culture-method for C. roscoffensis is described. Experiments have been carried out with various preparative methods for electron microscopy, and a method that yields adequate results with acoel material is described.
The epidermis is not syncytial, as has been maintained by some authors, but is composed of distinct, uninucleate cells. The cytoplasm of these has never been found to be continuous between cells, nor between the epidermis and the tissues that lie below it. The basal surfaces of the cells are intimately associated with the muscle layers and with other peripheral tissues. A brief account of the cytology of the epidermal cell is given.
The fine structure of the cilia and their rootlets is described from observations on sectioned material and on isolated, ‘negatively stained’ specimens. The rootlets of adjacent cilia make contact with each other in such a way as to preserve a hexagonal arrangement of the cilia, and yet to allow some degree of dimensional flexibility. The organization of the ciliary array over the surface of the animal is described. The ciliary ‘streamlines’ radiate outwards in all directions from a region (occupied by the frontal gland) at the anterior tip of the animal, and converge on a point at the posterior tip. This pattern is interrupted only in small regions near the mouth and the genital openings. The directions of beat and of metachronal-wave propagation are uniformly related to each other, and to the structural pattern, at all points.
Epidermal replacement has been studied experimentally in C. roscoffensis. Batches of animals were subjected to a surface-abrasive treatment, and epidermal-replacement cells were later identified in the parenchyma. The structure and situation of these is described, though their origin is not known.
The findings are discussed in relation to the variety and possible functions of ciliary rootlets, and to current concepts of acoel organization.
The cytology and histochemistry of the digestive gland cells of Helix
Authors: Sumner A. T. 
Published: April 2021

ABSTRACT
The digestive gland tubule epithelium of Helix aspersa is made up of 4 cell-types : thin cells, digestive cells, calcium cells, and excretory cells. Thin cells are narrow and undifferentiated. They divide by mitosis and are believed to develop into other celltypes. Digestive cells are highly vacuolated phagocytic and absorptive cells. Food materials are taken in by phagocytosis and are concentrated and digested in the vacuoles in the cell. When digestion is complete, the residual indigestible material in the vacuoles, and excretory material in the form of small granules of lipofuscin, are cast out of the cell surrounded by a portion of cytoplasm. Calcium cells are secretory, with a prominent Golgi apparatus and a high concentration of RNA in the cytoplasm. Most of the cell is occupied by spherules which contain calcium; apically there are protein granules which contain a high concentration of tryptophane. Both these types of inclusion are extruded from the cell. Protein granules may be zymogen granules, but the function of the calcium spherules is not known. Excretory cells are degenerate, and probably derived from calcium cells. They consist chiefly of a large vacuole, surrounded by a little cytoplasm. The vacuole contains one or more granules of lipofuscin. Similar granules can be found in the faeces, and thus they are excretory material.
Colour photomicrography of crystals in Brownian movement
Authors: Sassoon H. F. , Parsons M. H. C. 
Published: April 2021

ABSTRACT
Colour photomicrography of particles in Brownian movement has been achieved on High-Speed Ektachrome film using a flash source giving about 200 joules in 250 μsec. The design and operation of a prototype apparatus is described, and its potentiality for further development discussed.
Observations on the mastigonemes of two Chrysophyceae using negative staining
Authors: Bradley D. E. 
Published: April 2021

ABSTRACT
This paper describes a negative staining procedure for small appendages on relatively large organisms, and its application to the study of the ultrastructure of the mastigonemes of two chrysomonads. They have a remarkably complex structure, appearing as tubes with a layer of ragged material on their surfaces. In spite of the large amount of detail visible, it is not possible to propose a definite model of their structure.
The fine structure of the olfactory surface of teleostean fishes
Authors: Bannister L. H. 
Published: April 2021

ABSTRACT
The olfactory receptors of Phoxinus are of at least two distinct types: those with ciliated tips, and those with rod-shaped tips to their dendrites. Both Phoxinus and Gasterosteus possess ciliated receptors with 4 to 6 cilia arranged in a ring on each dendritic tip. The cilia resemble non-sensory motile cilia in most respects. They are, however, shorter, and lack ‘arms’ on the outer ring of double fibrils. They also lack striated rootlets, but possess basal feet, which point towards the centre of the ring of cilia. The rod-tipped receptors contain three or more longitudinally oriented bundles of fibres. Microtubules are present in receptor dendrites, in supporting cells, and in ciliated non-sensory cells. Their mean diameter in dendrites is 180 Å.
The different forms of receptor, and their function, are discussed.