bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Origin of Proteid Yolk in Drosophila melanogaster
Authors: Hsu W. Siang 
Published: April 2021

ABSTRACT
1. The origin of the proteid yolk granules in the eggs of Drosophila melanogaster has been traced to precursors embedded in the matrix material of flakes which are emitted by the nucleoli of the nurse cells.
2. These emissions are of a lipoidal nature, as shown by their behaviour towards fixatives and stains. They have never been observed to come from the nucleolus of the germinal vesicle.
3. The precursors, once released from the matrix of the flakes, develop directly into individual proteid yolk granules.
The Behaviour of the Nucleus during Spermatogenesis in Fasciola hepatica
Authors: John Bernard 
Published: April 2021

ABSTRACT
1. The behaviour of the nuclei of the male germ cells of F. hepatica L., as observed after fixation in Carnoy 6:3:1, is described and illustrated. All phases of the division and maturation of the male germ cells occur within the multi-branched and tubular testes. The daughter cells by remaining in association and dividing synchronously throughout these divisions eventually give rise to a spermatid rosette of thirty-two component cells. During spermiogenesis the nucleus of each individual spermatid cell undergoes a progressive elongation and is converted into an undifferentiated and homogeneous filiform thread.
2. The occurrence of globules of unknown origin, composition, and function is recorded within the peripheral border of spermatogonial primordia. Pycnotic primordial spermatogonia are also observed to originate in the peripheral testis cells.
3. The cyto-morphology of the chromosome complement is recorded in relation to size and the position of the attachment-constriction. The somatic number in the male cells is found to be 12 (diploid).
4. From a study of metaphase configurations chiasmata are shown to exhibit a normal distribution and there is no apparent localization of the chiasmata. The infrequent occurrence of chromatid bridges at anaphase I is correlated with the retention of an unusually large number of interstitial chiasmata.
Miscellaneous Contributions to Microtechnique
Authors: Baker John R. , Jordan Barbara M. 
Published: April 2021

ABSTRACT
1. The glycerine in Mayer’s glycerine and albumen serves no useful purpose.
2. If about one-half of the haematoxylin in such solutions as those of Heidenhain and Ehrlich be oxidized by sodium iodate, the dyes are ready for use the moment they have been made up and also keep well.
3. In using crystal violet for staining chromosomes, it is best to fix the dye by an aqueous (instead of the usual alcoholic) solution of iodine.
Standardization of Methyl Green for Specific Staining of Egg-shell Material in a Trematode
Authors: Smyth J. D. 
Published: April 2021

ABSTRACT
1. The specificity of a number of samples of methyl green for egg-shell material in Fasciola hepatica was investigated.
2. A method for distinguishing between specific and non-specific stains by paper chromatography is described.
3. Specific stains gave almost identical chromatograms with an Rf value of 0 83 for both green and violet constituents. Non-specific samples gave chromatograms with an Rf of 0·65 for the green constituent and an Rf of 0·84 for the violet constituent. The liquid phase used was a mixture of organic solvents in the following proportions: ethanol, 100; water, 80; n-butanol, 100; cellosolve, 100.
4. The application of this technique has led to the production of a methyl green, named Methyl Green M.2, specific for shell material in Fasciola.
The Relationship of the ‘A’ and ‘B’ Cells of the Pancreatic Islet Tissue of the Grass-snake (Natrix natrix)
Authors: Barrington E. J. W. 
Published: April 2021

ABSTRACT
An account is presented of some cytological characteristics of the pancreatic islet tissue of the grass-snake (Natrix natrix helvética), based upon supra-vital observations and upon the application of different techniques of fixation and staining. It is concluded that the so-called ‘A’ and ‘B’ cells contain granules of essentially the same type, and that they are stages in a single secretory cycle. It is suggested that the ‘A* cells constitute a relatively inactive storage phase, while the ‘B’ cells are concerned with the formation and discharge of the final secretory product, free phospholipine becoming demonstrable in association with the granules during this latter phase.
Cytological Studies of the Neurones of Locusta migratoria Part I. Cytoplasmic Inclusions of the Motor Neurones of the Adult
Authors: Shafiq Saiyid Ahmad 
Published: April 2021

ABSTRACT
The motor neurones of Locusta migratoria have the following inclusions in their cytoplasm:
(a) granular and filamentous mitochondria;
(b) lipochondria of various sizes. These are osmiophil and sudanophil. They also segregate neutral-red and other vital dyes. These ‘neutral-red bodies’ are shown not to be new formations in the cells, as was believed by Beams and King. The lipochondria may perhaps be homogeneous bodies, though in fixed preparations and also in life they sometimes appear to have a cortex and medulla. The osmiophil platelets and the straight and curved rods are shown to be artifact appearances caused by the action of Golgi techniques on the lipochondria, &c.;
(c) irregular vacuoles of various sizes;
(d) yellow globules in some neurones, especially from old locusts.
Measurements on Sea-urchin Eggs with an Interference Microscope
Authors: Mitchison J. M. , Swann M. M. 
Published: April 2021

ABSTRACT
Observations and measurements with an interference microscope on sea-urchin eggs have established the following points.
(1) The refractive index (R.I.) of the cytoplasm of the unfertilized egg is 1·375, which is equivalent to a concentration of solid matter of about 25 per cent. Very similar values were obtained from eggs 10 minutes after fertilization.
(2) There may be a small drop in the R.I. during the interphase before the first cleavage and during mitosis, but this is not greater than about 0·2 per cent., which is equivalent to a change in concentration of 2 per cent.
(3) The nucleus of the unfertilized egg has an R.I. of 1·360, equivalent to a concentration of 16 per cent.
(4) The R.I. of the mitotic figures is lower than that of the cytoplasm, by a ratio of 0·89 in metaphase. This is probably due to the absence of granules in the mitotic figures, since a similar ratio is obtained between the clear and the granular regions in centrifuged eggs.
(5) In metaphase, the chromosomes have the same R.I. as the spindle and are invisible. During the later stages of mitosis their R.I. drops, and they become visible.
(6) The dry thickness of the fertilization membrane is about 160 A. There is evidence of a colloid in the perivitelline space at a concentration of about 0-07 per cent.
(7) The jelly has a concentration of less than 0·0055 per cent.
The Structure of the Spermatozoa in Dextral and Sinistral Races of Limnaea peregra
Authors: Selman G. G. , Waddington C. H. 
Published: April 2021

ABSTRACT
Spermatozoa from dextrally and sinistrally coiled races of Limnaea peregra were examined by the use of an electron microscope. Helical fibres in the middle and tailpieces of the sperm were found to be dextrally coiled in preparations from individuals of both races. It is concluded that the genes which determine the direction of spiral cleavage in Limnaea do not control coiling in the sperm.
The structural features of the sperm are discussed in the light of limitations imposed by geometrical considerations on the form of the helical fibres.
Intracellular Membranes
Authors: Young J. Z. 
Published: April 2021

ABSTRACT
Spheres that stain with neutral red in cephalopod neurons show changes with variations in the tonicity of the surrounding medium. In hypertonic solutions the surface becomes shrunken and the stainable matter restricted to crescents or granules at the side of the sphere. These processes are reversible. They may be interpreted by considering that the surface of the spheres consists of material with properties partly analogous to those of a semi-permeable layer and partly to a membrane, that is to say a layer with tangential cohesive forces. These analogies are not perfect, however, and in particular the cohesive properties of the ‘membrane’ are limited and its material tends to flow together to form drops when the inner pressure is reduced.
The appearances produced by the classical methods for staining the Golgi apparatus are a result of distortions of these droplets similar to those produced by changes in tonicity. The outer more osmiophil or argentophil component adopts forms reminiscent of those shown by the component that stains more deeply with neutral red.
On the role of the integument in acarine development and its bearing on pupa-formation
Authors: Jones Bryn M. 
Published: April 2021

ABSTRACT
Typical development in mites begins with the retraction of the epidermis from the cuticle. It is accompanied by a decrease in size and a change in shape. Atypical development also begins with a moult. But it is distinguished by regrowth, a change in shape, and an extra moult.
Each moult is unique in that the epidermis divides into an outer and an inner layer. The outer layer adheres to the old cuticle. Its cells are provisionally regarded as being the source of the moulting enzymes. The inner layer retracts and persists as the true epidermis.
The components of mite cuticle, according to histochemical tests, resemble those of insect cuticle.
The formation of a provisional cuticle during atypical development produces the condition generally recognized as a pupal state. The moult of this provisional cuticle is primarily aimed towards synchronizing cuticle deposition with muscle development. Integration of the intermediary connecting processes, the fibrillae, with both the muscle ends and the cuticle is thus made possible.
The Thoracic Glands of Hemiptera Heteroptera
Authors: Wells M. J. 
Published: April 2021

ABSTRACT
The thoracic glands of the pyrrhocorid Dysdercus cingulatus are described. They originate in the second maxillary segment and grow backwards with the salivary gland system. During post-embryonic development the gland nuclei increase in size but not in numbers. In each instar they enlarge, discharge their secretion, and shrink. The thoracic glands of ten other Heteroptera from eight families are described. All consist of large granular nuclei with little surrounding cytoplasm, most commonly arranged as a pair of elongated ductless glands lying parallel to the salivary ducts and attached distally to either the principal or the accessory glands. The thoracic glands are well supplied with tracheoles, but unlike other insects in which corresponding organs have been described, do not appear to have a nerve supply. The number of nuclei in each gland is surprisingly constant, being about 300 in almost all the species examined, the volume of the gland being greater in the larger insects by increase in the size of individual nuclei. The glands disappear very rapidly after the last moult.
The Optical Measurement of Depth
Authors: Galbraith W. 
Published: April 2021

ABSTRACT
The formula for vertical measurement by means of the fine adjustment of the microscope, n2/n1 × measured depth = real depth, is true, where n2 is the refractive index of the object and n, is that of the immersion medium of the objective lens. The refractive index of the mountant is unimportant.
Several additional complications of this method of measurement suggest that it should not be used unless it cannot be avoided, or rough figures are required quickly.
A Study of the Argentaffin (Kultschitzky) Cells in frozen-dried Tissue by Phase-Contrast Microscopy and Ultra-Violet Light
Authors: Christie A. C. 
Published: April 2021

ABSTRACT
The argentaffin cells in guinea-pig intestine have been studied by phase-contrast microscopy and in ultra-violet light. Frozen-dried tissue has been used. One such cell in a section 5–7μ thick was selected and studied throughout. In an unfixed section mounted in nonane, the cytoplasm is packed with fine granules which emit a greenish-yellow fluorescence in ultra-violet light of wavelength 2,750 Å. There is also photographic evidence of absorption of light of this wavelength. After formaldehyde fixation the fluorescence changes to orange-yellow and becomes much weaker. The absorption of light by the granular cytoplasmic contents is also greatly reduced. There is no fluorescence and no photographic evidence of absorption of light of wavelength 2570 A by the granular cytoplasmic contents, either before or after formaldehyde fixation. The nuclear chromatin pattern in these cells is unaltered by formaldehyde fixation, and is well demonstrated in photographs taken in ultra-violet light of both the wavelengths mentioned above.
The Sheath of Spicules of Leucosolenia complicata
Authors: Jones Walter Clifford 
Published: April 2021

ABSTRACT
Dilute hydrochloric acid, carbonic acid, and potassium nitrate solutions dissolve the spicule calcite revealing a thin, partially contracted sheath. Corrosion by potash solution, however, produces a rigid, brittle ‘sheath’, which consists of the true sheath and an inorganic deposit laid down on its inner surface as the calcite dissolves away.
The oscular rays, gastral rays, and curved monaxons corrode much more rapidly than the basal rays and slender monaxons in potash solution, and the corrosion is most noticeable on the surfaces transverse to the optic axis, particularly when dilute potash is used. Potassium nitrate solution and water, however, corrode the surfaces parallel to the optic axis, whereas in hydrochloric and carbonic acid solutions the calcite dissolves uniformly all round the rays.
When spicules bearing calcite crystals are corroded, the calcite of the spicules dissolves more rapidly than the crystals, which then remain attached to the sheath and appear to have crystallized upon it, though attempts to crystallize calcite upon isolated sheaths, or sheaths supported by the inorganic deposit, have been unsuccessful. The evidence suggests that when crystals form on the spicule surface they are oriented by crystallizing on the calcite through perforations in the sheath.
The Cell-theory : a Restatement, History, and Critique: Part V. The Multiplication of Nuclei
Authors: Baker John R. 
Published: April 2021

ABSTRACT
The belief that nuclei arose by exogeny, without relation to pre-existent nuclei, was due mostly to Schleiden (1838). Kôlliker (1843) supposed that new nuclei arose by endogeny within pre-existent nuclei.
Other early theories of the origin of nuclei contained a considerable element of truth. Many early workers thought that the ordinary nuclei of many-celled plants and animals multiplied by division (Bagge, 1841 ; Nageli, 1844; von Baer, 1846), or by the disappearance of the old nucleus and its immediate replacement by two new ones (Nageli, 1841 ; Reichert, 1846).
The history of the discovery of mitosis falls into three parts.
Observations on the Stomach and Digestive Diverticula of the Lamellibranchia: I. The Anisomyaria and Eulamellibranchia
Authors: Owen G. 
Published: April 2021

ABSTRACT
A study of the digestive diverticula of the Anisomyaria and Eulamellibranchia revealed certain features hitherto undescribed. The diverticula consist of blind-ending tubules which open into ciliated main ducts by way of short, non-ciliated secondary ducts. The main ducts open into the intestinal groove. In all the species examined the ciliated epithelium of the main ducts was restricted to a well-defined groove, the remainder of the lumen being surrounded by a non-ciliated, brush-border epithelium.
Each tubule is surrounded by a system of smooth muscle fibres. Cilia associated with the darkly staining cells of the crypts were demonstrated in sections of the tubules. After feeding with titanium dioxide in suspension, this substance was later found in the large vacuolated cells of the tubules. The particles of titanium dioxide were larger than 0·1.
A continuous circulation is maintained within the main ducts solely as a result of ciliary activity. The exhalant current in the ciliated portion of the main ducts produces an inhalant counterpart current in the non-ciliated portion. It is suggested that fresh fluid is drawn into the tubules as a consequence of the absorptive functions of the large vacuolated cells. Indigestible material accumulates in the large vacuolated cells and is extruded into the main ducts where it is conveyed out of the diverticula by the exhalant ciliary current.
In both the Anisomyaria and Eulamellibranchia the flap-like major typhlosole prevents material entering the mid-gut except by the intestinal groove, and isolates the rejectory currents of the intestinal groove from the general circulation of particles in the stomach. In the Eulamellibranchia the major typhlosole also acts as a valve which controls the entry and exit of material into and out of the inhalant and exhalant portions of the main ducts.
A Pigment in the Rat’s Uterus
Authors: Warbrick J. G. 
Published: April 2021

ABSTRACT
A yellowish-brown pigment was found at the old placental sites in rats killed at 10 and 20 days after littering. The pigment contained ferric iron and therefore may be regarded as haemosiderin. Other properties of the pigment suggest that there is also a lipid component present. Lipid is not usually associated with haemosiderin. The lipid component behaves in many ways like the lipogenic pigments.
The Site of Damage in Amoebae exposed to Low Concentrations of Methyl di-(β-Chloroethyl)-Amine (a ‘Nitrogen Mustard’)
Authors: Ord M. J. 
Published: April 2021

ABSTRACT
Amoeba proteus was exposed to a low concentration of methyl di-(β-chloroethyl) amine (MBA, a ‘nitrogen mustard’). Subsequent nuclear transfer was used to study the relative sensitivities of nucleus and cytoplasm to MBA. Nuclei were found to be 10 times as sensitive as cytoplasm. Exposure to MBA caused a short delay before the first division of the nucleus and a longer delay before the second division, the delay before the first division being more marked with exposure to LD100 or higher concentrations. The first cytoplasmic division was delayed after treatment but subsequent division showed little change. MBA caused many abnormalities in division. When cytoplasm was injured the nuclei became swollen or, with less severe damage, divided without subsequent cytoplasmic division. When only nuclear damage was present, such abnormalities as incomplete prophase, non-nucleate division, uneven division, and cytoplasmic fragmentation occurred.
Neurosecretory Cells of the Central Nervous System of the Crab, Paratelphusa hydrodromous
Authors: Parameswaran R. 
Published: April 2021

ABSTRACT
Three types of neurosecretory cells, designated A, B, and C, occur in the central nervous system of Paratelphusa hydrodromous. They are distinguishable by their sizes, the nature of their nuclei, and the secretory products in the cytoplasm. Their distribution and neurosecretory activity are recorded in this paper. All the three types occur in the thoracic ganglion, while the brain and tritocerebral connective ganglia contain only the A and B types. Examined alive under the phase-contrast microscope, the conspicuous A-cells reveal the presence of numerous tiny granules and dark spheroids in the cytoplasm. These spheroids are stainable by neutral red. In Golgi preparations the spheroid walls become black. These are sudanophil and probably represent lipochondria. The spheroids contain phospholipid and vitamin C. The granules of the cytoplasm probably represent the mitochondria.
The brain and thoracic ganglia contain within them a rich network of delicate capillaries which surround individual neurosecretory cells as well as groups of cells. The secretory products are possibly discharged directly into the blood.
A Histochemical Basis for Changes in Renal Tubular Function in Young Mice
Authors: Longley James B. , Fisher Edwin R. 
Published: April 2021

ABSTRACT
In the kidney of the adult mouse the tubular epithelium in the most proximal (P1) segment, corresponding roughly to the convoluted portion of the proximal tubule, shows strong alkaline phosphatase activity, and the brush border is moderately reactive to the periodic acid Schiff (PAS) method. In the more distal (P2) segment of the proximal tubule there is no alkaline phosphatase activity, and the PAS reaction of the brush border is intense. Examination of a large number of young mice has now revealed a distinct pattern in the development of this adult condition.
Differentiation of the two segments on the basis of the PAS reaction of the brush border becomes apparent on about the 15th post-natal day. The effect is the result of a decrease in the reactivity of the Pi segment. Differentiation of the two segments on the basis of alkaline phosphatase activity develops gradually between about the 22nd and 36th post-natal days. During this period the alkaline phosphatase activity disappears progressively from the proximal to the distal end of the P2 segment.
The administration of testosterone or estradiol to either sex accelerates the differentiation with respect to alkaline phosphatase activity. Castration of male mice retards the completion of this process.
It is suggested that morphological changes of this type may provide the basis for some of the functional differences between the kidneys of young and mature animals.
Distribution of Iron in Daphnia in Relation to Haemoglobin Synthesis and Breakdown
Authors: Smaridge M. Wendy 
Published: April 2021

ABSTRACT
Daphnia synthesizes haemoglobin in poorly aerated water and loses it in well-aerated water. A histochemical study has been made of iron in the tissues of partheno-genetic female D. magnawhen gaining or losing haemoglobin, and with a steady content of the respiratory pigment.
In animals gaining haemoglobin, loosely-bound iron was found especially in the gutwall, fat-cells, and ovaries. The iron in the gut-wall was probably being absorbed into the body, and that in fat-cells and ovary being incorporated into newly synthesized haemoglobin.
In animals losing haemoglobin, loosely-bound iron was found especially in the walls of the gut caeca, in the fat-cells, and in the excretory shell-glands. Several lines of evidence indicate that iron was being excreted by the shell-glands. It was probably also being excreted through the gut caeca. In the fat-cells haemoglobin can accumulate during haemoglobin loss and it is probably broken down here with the deposition of iron. This iron is subsequently excreted.
Colloidal Properties of the Mesogloea in Species of Leucosolenia
Authors: Jones Walter Clifford 
Published: April 2021

ABSTRACT
Oscular tubes rapidly collapse and disperse in isotonic potassium nitrate solution, the cells dissociating and rounding off, and the mesogloea softening and swelling. Reasons are given for regarding the action as a direct one on the mesogloea and intercellular ‘cement’.
Transference of the collapsing tubes to sea-water, or isotonic calcium chloride, results in an immediate stiffening of the mesogloea, and the swollen cells form characteristic processes which are best seen after the cells have been in the nitrate solution for an optimum period depending on the temperature. They are not formed after treatment with M/1oo potassium cyanide.
The action of other isotonic salt solutions is briefly described. When a comparison is made of the times taken for the tubes to become plastic, the ions respectively used fall into three series which are the same as those found in regard to the dispersiveness of certain hydrophilic organic colloids.
The experiments provide evidence that the mesogloea is secreted by the choanocytes or by the amoebocytes close beneath them, and that the secretion stiffens into a firmer gel as it passes into the spicule zone. The degree of firmness also varies apparently according to the health of the tube.
The action of distilled water and acidified sea-water are described. After the spicules have dissolved the tube still retains its shape and much of its support can thus derive from the mesogloea. The relative functions of the mesogloea and the spicules are briefly discussed.