bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Integration Method for the Interference Microscope
Authors: Mitchison J. M. , Passano L. M. , Smith F. H. 
Published: April 2021

ABSTRACT
A method is described of measuring the integrated phase retardation of an object with a Baker interference microscope. With certain limitations, the total dry mass of the object can be derived from this figure. This method of ‘weighing’ objects is of particular value in measuring the growth of single cells, since it is very sensitive and can be used on a living cell without damaging it.
The method consists of restricting the field round the object with an aperture of known area and then measuring the total retardation within this field due to the presence of the object. The compensator is adjusted until there is an equal light intensity in the field with and without the presence of a quarter-wave plate. A similar adjustment is made with the object moved out of the field. The difference between the two compensator settings gives the integrated area retardation due to the object. The quarter-wave plate is motor-driven, and the light intensity is measured by a photomultiplier and presented on a cathode ray tube. The instrument is sensitive to a change of about 5 × 10_ 14 g in the dry weight of a biological object.
For an object of known specific refractive increment and mounted in water, the total dry mass can be derived from the retardation without the dimensions of the object being known. There is, however, a severe limitation with this method of integration— that the maximum retardation of the object must not exceed about 45 º or λ/8. This can be shown by theory, and has also been confirmed by model experiments with small celloidin spheres. Most biological objects have larger retardations in water, so it is necessary to mount them in media of higher refractive index. In this case, the volume of the object must also be known for the dry mass calculation. Although this limits the use of the method, it is important in measuring the growth of a cell to know the volume as well as the dry mass.
An example is shown of the application of this method in measuring the growth of a fission yeast, Schizosaccharomyces pombe. Curves are given showing the changes in dry mass, volume, and concentration of a single growing and dividing cell of this yeast.
The Structure of the Teeth of some Mammal-like Reptiles
Authors: Poole D. F. G. 
Published: April 2021

ABSTRACT
The principal changes in calcified tissues which have fossilized are the loss of organic material and the conversion of hydroxyapatite into fluorapatite. Since these two minerals are very similar and because, initially, mammalian enamel has a low organic content, its optical properties are hardly affected by fossilization. On the other hand, the loss of optically active collagen results in a modification of the characters of dentine.
The teeth of synapsid reptiles possess dentine similar to that of recent reptiles. Occasionally the dentine contained globuli, but unlike mammalian dentine, there appeared to be no ‘spheritic’ orientation of crystallites within the globuli. Certain dicynodont tusks consisted of dentine only and it is possible that enamel was missing even in the original condition. Other synapsid teeth possessed a thin, well-defined enamel layer made up of incremental lamellae but lacking true prisms. Nevertheless, cylindrical groups of crystallites exist throughout this enamel within which the orientation of the crystallite axes varies regularly. Between crossed nicols of a polarizing microscope this crystallite arrangement gives the enamel a prismatic appearance. However, the enamel is quite homogeneous, for these pseudo-prisms are not physically separated from each other. Furthermore, this regular prismatic appearance and an irregular Säulengliederung, such as occurs in crocodile enamel, may exist in the same tooth. There is, therefore, no evidence that the prismatic enamel characteristic of mammals existed in the pre-mammalian reptiles.
Preservation of Animal Tissues, with a Note on Staining Solutions
Authors: Owen G. , Steedman H. F. 
Published: April 2021

ABSTRACT
Methods are given by which animal material, fixed by any desired method, may be preserved against attack by fungi or bacteria. The reagents employed are glycol monophenyl ethers (‘Phenoxetol’), and esters of p-hydroxybenzoic acid (‘Nipa’ esters). These reagents, dissolved in water, produce colourless and almost odourless solutions, in which a variety of animals have been preserved for many months without showing any traces of deterioration or decomposition.
Mucopolysaccharides and the Calcification of the Scale of the Roach (Leuciscus rutilus)
Authors: Wallin O. 
Published: April 2021

ABSTRACT
The scale of the roach (Leuciscus rutilus L.) was examined for state of calcification, metachromasy, and reaction to the periodic acid / Schiff (PAS) test. Metachromasy and a positive PAS-reaction imply acid mucopolysaccharides in the bony layer. There is a great increase in these reactions and in reactions for bone salts in the transition zone between the uncalcified and calcified part of the bony layer. These reactions imply that the bond between the osseoid and the inorganic fraction of the bony layer is through SO2-and PO4-groupings. The fibrillary plate lacks metachromasy, but shows a positive PAS-reaction. Before calcification a strong orthochromasy points to acid groups in connexion with the collagen. Under the radii there is no orthochromasy, and the PAS-reaction is negative. When calcifying, the fibrillary plate loses its orthochromasy and the mineral matter is deposited as large crystal-complexes. In regenerating scales the reactions are weaker than in normal scales.
The Morphology and Origin of the Golgi Bodies and their Role in the Secretion of the Acrosome in the Spermatogenesis of Pulmonate Gastropods as Determined in the Living Material by Phase-contrast Microscopy
Authors: Nath Vishwa , Gupta Brij L. 
Published: April 2021

ABSTRACT
In this paper are embodied our observations on the morphology, origin, and role of the Golgi bodies in the spermatogenesis of the slug, Anadenus altivagus, and the snail, Euaustenia cassida. Living cells have been studied under the phase-contrast microscope and photomicrographed. In the juxta-nuclear Golgi region in primary spermatocytes the Golgi bodies exist in the form of (1) granules and rods of dark contrast, (2) spheres of pale contrast, and (3) spheroids showing a duplex structure, each consisting of a sphere of pale contrast and an incomplete or complete cortex or sheath of dark contrast. The Golgi spheroids have been shown to arise three times in the course of spermatogenesis from the mitochondrial granules by a process of alignment. The acrosome is formed from a cap of tiny acrosomal granules, which are deposited in front of the spermatid nucleus by the Golgi bodies (acroblasts).
Some Observations upon the Cytology of the Pars Distalis of the Surgically-removed Human Pituitary
Authors: Foster C. L. 
Published: April 2021

ABSTRACT
Human anterior pituitary tissue that had been removed at operation and immediately fixed was examined by a number of cytological and histochemical methods and by phase contrast and electron microscopy, and compared with similar material obtained post mortem. The general histological picture of good post-mortem material (not more than 4 hours post mortem) compared well with the surgically-removed tissue. For the study of silver impregnations of the Golgi substance, however, material removed at operation was found to be greatly superior.
Evidence was obtained showing that the intracellular lipid inclusions seen post mortem were not artifacts resulting from cytolytic changes. There appeared to be no relationship between these lipid bodies and the Golgi material as revealed by the Aoyama method.
No unequivocal dimorphism of the Golgi bodies, correlated with α-and α-celIs, such as has been reported to occur in certain other mammals, was observed.
Phospholipid was present in the granules of a substantial proportion of the α-cells.
It was found that most of the cells which had been designated as β-cells after the application of certain routine staining methods, and most of the Gram-positive cells, reacted positively to the Periodic acid Schiff test: these cells could therefore be regarded as true β-or mucoid cells.
A method for the demonstration in frozen sections of the cell-types, together with the lipid inclusions, is described.
Some Cytological Characteristics of Thyroidal Function in the Endostyle of the Ammocoete Larva
Authors: Barrington E. J. W. , Franchi L. L. 
Published: April 2021

ABSTRACT
An account is given of the distribution of thyroidal function in the epithelium of the endostyle of the ammocoete larva, based on the localization of bound iodine as revealed by autoradiographs ; and the cytological characteristics of the various types of cells are analysed in relation to this. The binding of iodine is shown to be correlated with the production of a PAS-positive ‘thyroidal prosecretion’ which, in fully active cells, tends to become transformed into a more granule-like phase. These thyroidal granules appear to have some degree of permanence and to enlarge by the accumulation of material ; the precise significance of this is not clear, but it might involve the laying-down either of secretory reserves or of the by-products of thyroidal metabolism. The granules differ from the initial phase of the prosecretion in developing a brown pigmentation, a positive ferric-ferricyanide response, and a yellowish fluorescence, together with some affinity for orange G. These properties, together with the PAS-positive response of both phases of the prosecretion, give considerable support to the view that the secretory process involved is homologous with that which produces thyroid colloid in higher forms, although the histochemical reactions concerned are not sufficiently specific to be decisive. Thyroidal function is widely spread in the epithelium, except in the glandular tracts (type 1 cells), but it varies in its degree of expression; the pattern of this, and its relationship to the alimentary activity of the endostyle, can conveniently be described in terms of the embryological concept of ‘gradient fields’. The present results are discussed in relation to the fate of certain regions of the epithelium at metamorphosis.
Some Observations upon the Golgi Elements of the Cells of the Surgically Removed Human Anterior Pituitary
Authors: Foster C. L. 
Published: April 2021

ABSTRACT
1. The lipid inclusions of the cells of the pars distalis of the human pituitary are not restricted to the zone occupied by the Golgi element.
2. No evidence was obtained to suggest that a canalicular system is invariably associated with the Golgi zone. The frequency with which such systems were observed appeared to depend on the mode of fixation and other factors.
A Histochemical Study of the Adipose Cell of the Leech, Glossiphonia complanata
Authors: Bradbury S. 
Published: April 2021

ABSTRACT
The adipose cell of the leech Glossiphonia complanata has been studied both morphologically and histochemically. It is more or less globular in shape, with a diameter of from 10 μto 40μ; the protoplasm is clearly marked off into two zones, the ground cytoplasm around the periphery of the cell, and a denser, basiphil zone (termed the ‘surround’) which encloses the fat drops and the nucleus. Large thread-like mitochondria are scattered throughout the cell ; they are especially numerous in the ‘surround’.
Histochemical tests showed that the ground cytoplasm contained arginine, tyrosine, glycogen, RNA, and inorganic iron; the ‘surround’ has, in addition to these, much phospholipid, some unsaturated lipid, and some acid mucopolysaccharide.
The large fat drops and some other smaller fat droplets found in the ground cytoplasm are chiefly composed of neutral lipid, possibly triglyceride; they also contain some cholesterol or cholesteryl esters and some unsaturated lipid. The lipochondria of the ground cytoplasm and the ‘surround’ differ from these in that although they may contain some or all of the substances found in the large fat drops, their principal constituent is phospholipid. The mitochondria also react positively to the test for phospholipid.
Some granules found in the ‘surround’ and in the ground cytoplasm were shown to contain inorganic iron. The ‘fuchsinophil’ granules of Bobin are almost certainly identical with the lipochondria.
Both the large fat drop and the glycogen are reserve food stores.
The use of the baker interference microscope for the study of optically heterogeneous specimens
Authors: Faust R. C. 
Published: April 2021

ABSTRACT
The refractive index of an optically heterogeneous specimen will generally vary in directions parallel and normal to the microscope axis, but a mean index can be defined such that the optical thickness of the specimen is equal to the product of the mean index and the specimen thickness. If such a specimen is examined under an interference microscope, the fringe displacement will be zero at those parts of the specimen for which the mean index is equal to the index of the immersion liquid. Thus, by gradually changing the index of the liquid relative to that of the specimen, one can determine the manner in which the mean index varies from region to region of the specimen. In the present work these changes in relative index have been effected by varying either the wavelength of the incident light or the temperature of the system.
The Baker two-beam interference microscope has been successfully used for such investigations. Three types of interference pattern have been tried: (i) a single fringe is made to fill the field of view and the intensity differences between the specimen and the background are studied; (ii) monochromatic fringes are formed in a quartz wedge and their linear displacements are examined; and (iii) a quartz plate is used, channelled spectra being produced by the spectrographic analysis of the interference colours. The first two types can be used with either the temperature or the wavelength variation method, but the third was specifically designed for use with the wavelength variation method. Although these experiments have mostly been carried out on birefringent fibres, the techniques are applicable to any kind of object. The attainable accuracy increases with specimen thickness; under favourable circumstances the index at any point of a specimen io µ thick should not be in error by more than ±3 × 10-4.
A Modified Ester Wax for Embedding Tissues
Authors: Chesterman W. , Leach E. H. 
Published: April 2021

ABSTRACT
1. A modification of Steedman’s ester wax embedding method is described. This involved purification of two of the components—diethylene glycol monostearate and distearate. The puckering and floating off of the sections is thereby minimized.
2. The method is particularly applicable to tissues containing much collagen and to tissues that have been badly fixed or which have undergone post-mortem degeneration.
3. Cytological preservation is improved, especially that of such substances as glycoproteins and mucoproteins.
The Male Genital System of the Scorpion, Buthus quinquestriatus
Authors: Abd-El-Wahab A. 
Published: April 2021

ABSTRACT
1. The paper consists of a morphological and histological description of the male genital system of the scorpion, Buthus quinquestriatus (H.E.).
2. There is a well-developed ganglionic mass at the extreme end of the lumen of the cylindrical gland. This ganglionic mass has not been recorded by any of the previous authors.
3. There are two pairs of annex glands opening into the common genital chamber. None of the previous authors have observed such a gland with the exception of Pavlovsky (1915), who recorded it in B. australis.
4. New methods have been adopted to resolve the structure of the ejaculatory organ and its supporting shaft. The organs were cut in serial transverse sections, and whole mounts were also made.
5. In the supporting shaft, several basal processes have been found, namely, the oblique vertical, longitudinal, superior, and inferior outer and inner processes.
6. The supporting shaft is found to be of a chitinous nature.
Seasonal Lipid Changes in the Sexual Elements of a Male Snake, Vipera berus
Authors: Marshall A. J. , Woolf F. M. 
Published: April 2021

ABSTRACT
In the seminiferous tubules and interstitium of the viper there occur cyclical changes basically similar to those in birds and the pike. These involve the metamorphosis of unshed germinal material into cholesterol-positive lipids, the rehabilitation of the interstitium after the seasonal depletion of its cytoplasmic lipids and cholesterol shortly after the spring emergence from hibernation, and the completion of spermatogenesis after basking in the sun. The viper differs from birds in that its tubule lipids contain much less cholesterol; also, the subsequent spermatogenesis begins almost immediately (as in poikilothermous pike and frog), and proceeds to the spermatid stage in the presence of such lipids. Further, although in some individuals new Leydig cells rapidly mature, this resurgence is delayed in others. Thus, although the succeeding spermatogenesis always begins in still-lipoidal tubules, it may do so in the presence of a largely non-lipoidal interstitium. Mitoses were observed in mature Leydig cells. Fibroblasts occasionally alter to take on an apparently glandular function.
By July most animals had regained a heavy lipoidal and cholesterol-positive interstitium, lost most of their tubule lipids, and possessed either secondary spermatocytes or, sometimes, spermatids. This internal activity is probably partly responsible for autumnal sexual behaviour. Factors additional to temperature control spermatogenesis, for only a few spermatozoa are formed by the time of hibernation in October. No pronounced retrogressive changes occur during hibernation: the cycle merely halts, and begins without further delay on emergence. Thus spermatogenesis may be at its peak by the end of March.
The expanded, glandular ‘sexual segment’ of the male renal tubule also exhibits cyclical changes involving the production and expenditure of cholesterol-positive lipids, but such changes take place also in narrow parts of the tubule and, further, in the kidney of the female.
The Contractility and Healing Behaviour of Pieces of Leucosolenia complicata
Authors: Jones Walter Clifford 
Published: April 2021

ABSTRACT
The behaviour of isolated pieces of Leucosolenia complicata confirms that this sponge vis contractile. The pieces first curl up owing to a contraction of the internal epithelium, which can exert a tension in one direction (transverse) more than the other at right angles. The contraction is slow because it entails a redistribution of the supporting mesogloea. It is abolished by 5 minutes’ treatment with distilled water.
Healing next involves the formation of ‘healing membranes’. Each membrane consists of two epithelia with a thin layer of mesogloea in between. The membranes arise either as an outfolding of the internal epithelium or from the cut edges of the wall, and they spread between the edges so that the tubular form of the olynthus is regained. Their spread is due to the maintenance of tension in the membrane, coupled with the shrinkage of the remainder of the piece.
Pieces from which the internal epithelium has been brushed away shrink rapidly and become saddle-shaped, indicating that the dermal epithelium also is contractile.
No important differences are noticeable when the healing behaviour takes place in equal parts of sea-water and isotonic magnesium chloride, which suggests that the behaviour is not under the control of a nervous system.
A discussion is given on the elements responsible for the contractility of the internal epithelium. It is probable that the porocytes are connected beneath the bases of the collar-cells, and are the contractile cells concerned.
The Anatomy of the Infra-red Sense Organ in the Facial Pit of Pit Vipers
Authors: Bullock Theodore H. , Fox Wade 
Published: April 2021

ABSTRACT
The histological composition, of the sensory membrane in the facial pit of rattlesnakes (Crotalus spp.), the disposition of the nerve-trunks entering it, the fibre-size spectrum of the nerves, and the form of the sensory endings are described. Between the two layers of extremely attenuated epidermis the principal constituent of the membrane is a single layer of specialized parenchyma cells with osmiophil, reticular cytoplasm. These are not regarded as sense cells but they react strongly and locally to degeneration of nerve-endings. The axons enter through numerous trunks from three branches of the trigeminal nerve, from all sides of the membrane, providing a dense innervation. They lose their myelin, taper to about 1 p, then expand into flattened palmate structures which bear many branched processes terminating freely over an average area of about 1,500 p.2, overlapping only slightly with adjacent units but leaving virtually no area unsupplied. This means there are from 5 00 to 1,5 00 axons ending per mm2, an estimate which agrees with the nerve-counts. No other form of ending was found. The mode of the fibre-size spectrum lies in the region 5-7p diameter. A transmission spectrum of the fresh membrane shows broad absorption peaks at 3 and 6 p and about 50% transmitted in other regions out to 16p. The visible spectrum is at least 50% transmitted and probably much is lost by reflection. Strong absorption takes place at wavelengths shorter than 490 p. The anatomical adaptations of the sense organ are discussed, especially the concentration of warm receptor fibres, the thinness of the membrane, the extremely superficial position of the nerve-endings—all increasing sensitivity to caloric flux. The overhanging margins of the pit and the richness of supply are believed to permit directionality of reception. It is suggested that the palmate form of the ending has a significance in permitting several independent local subthreshold activity generators to coexist in the processes and in pooling their coincident, electrotonically spread potentials to influence the initiation of spikes which may take place at the junction of axon and palm.
Spider Leg-muscles and the Autotomy Mechanism
Authors: Parry D. A. 
Published: April 2021

ABSTRACT
Spider leg-muscles have been redescribed and the absence of extensor muscles at two joints confirmed. The possibility that the flexors at these joints act in antagonism to the blood-pressure is discussed. The coxal muscles are inserted on to sclerites in the rim of the trochanter and autotomy occurs at this joint. At autotomy the sclerites are detached from the trochanter and support the articular membrane, which restricts bleeding.
The Uptake of 38S in Cortical Bone
Authors: Lea Lorna , Vaughan Janet 
Published: April 2021

ABSTRACT
A further study of the uptake of 35S in rabbits and in normal and rachitic puppies has been undertaken. The non-labile 35S present in osteoid tissue is removed by testicular hyaluronidase, but not by staphylococcal hyaluronidase, which suggests that it is chondroitin sulphate A or C. The non-labile 35S is first taken up by noncalcified osteoid tissue in the area giving a pale pink PAS reaction. It is only later found in calcified bone when the tissue ceases to be PAS-positive. Rigid attention to technical detail is essential if comparable results are to be obtained in studies of borte uptake of 35S.