bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spicule Growth Rates in Leucosolenia variabilis
Authors: Clifford Jones W. 
Published: April 2021

ABSTRACT
The growth rates of spicules of Leucosolenia variabilis have been determined by photographing stretched pieces of the wall for a maximum period of 17 h. For 3 pieces, A, B, and C, the average rates for spicule rays above 25 μ in length were respectively 2 · 50 (18 – 21° C), 1 · 64 (18° C), and 1 · 29 (17 ° C) μ per h. The discrepancies are greater than would be expected from the differences in temperature.
For both basal and oscular rays the growth rate increases to a steady level as the rays lengthen. The basal rays grow precociously at first, but in A the oscular rays soon caught up with the associated basal ray, while in B and C (both derived from the same oscular tube) the oscular rays of the growing spicules tended to remain smallerthan the associated basal ray during the recorded period of growth. Whether this difference between the pieces was due to genetic factors or to the experimental conditions was not determined.
Above 25 μ in length the oscular and basal rays grow at similar rates, regardless of whether the rays belong to Y-, T-, or even aberrant spicules. The orientation of the optic axis of the mineral constituent has thus no appreciable effect on the growth rate.
The Mesogloea of Pelagia noctiluca
Authors: Chapman G. 
Published: April 2021

ABSTRACT
The arrangement of the mesogloea fibres of Pelagia noctiluca is described chiefly from material examined in the fresh state.
The role of the mesogloea in swimming is shown to be the antagonization of the subumbrellar circumferential muscles.
The fibres of the mesogloea are shown to be collagenous by their contraction on heating, their amino-acid composition, and their appearance under the electron microscope.
A suggestion is made to account for the characteristic arrangement of the fibres at a distance from the cellular layers.
An Occurrence of Hermaphroditism in Rana catesbiana
Authors: O’steen W. Keith 
Published: April 2021

ABSTRACT
Hermaphroditism is rather uncommon in the bullfrog, Rana catesbiana. A case is described here. Among the features of the unusual urogenital system were male secondary sexual characters (large tympanic membrane, vocal sacs, nuptial pads), testicular tissue with developing and mature male gametes, and accessory ducts (vasa efferentia, seminal vesicles). Müllerian ducts and large ovarian masses containing oöcytes and mature ova were also present. Oocytes were observed in the lumina of seminiferous tubules.
A Modification of the ‘Hermann PO’ Method for Mitochondria
Authors: Jordan-Luke Barbara M. 
Published: April 2021

ABSTRACT
Hermann’s fluid is an excellent fixative for mitochondria, provided that the tissue is postosmicated; and if the postosmication is carried out for several days at 34° C, the mitochondria are blackened (Baker, 1957). This is probably the easiest and most satisfactory way of making mitochondrial preparations for light microscopy. Filamentous mitochondria retain their form.
The Nissl-Golgi Complex in the Purkinje Cells of the Tawny Owl, Strix aluco
Authors: Malhotra S. K. 
Published: April 2021

ABSTRACT
The purpose of this investigation was to repeat as exactly as possible the original work on the ‘apparatus’ of Golgi in the Purkinje cells of the cerebellum of owls, and to re-investigate these cells by modem methods. The tawny owl, Strix aluco, was used instead of the closely-related ‘Strix flammea’ of Golgi. Golgi’s ‘osmio-bichromique’ technique of 1898 for silver impregnation was used successfully.
A reticulum corresponding to the basiphil Nets of Nissl can be seen in the living neurones by interference microscopy. The classical Golgi apparatus of the perikaryon is a deposit of silver or of osmium on this reticulum. The reticulum extends into the axons in the form of thin non-basiphil filaments, which are also blackened by Golgi methods.
These findings are in conformity with recent studies of the neurones of other vertebrates.
A Method of Silvering the ‘Golgi Apparatus’ (Nissl Network) in Paraffin Sections of the Central Nervous System of Vertebrates
Authors: David G. B. , Mallion K. B. , Brown A. W. 
Published: April 2021

ABSTRACT
I. It was accidentally found that methods of silvering synaptic end-feet sometimes blackened Golgi’s ‘internal reticular apparatus’ in neurones of the central nervous system of the cat.
2. A method of achieving this consistently was worked out: (a) paraffin sections are coated with a collodion membrane; (b) the collodion membrane is soaked in silver nitrate; (c) the silver nitrate is reduced to metallic silver with a buffered formaldehyde solution; (d) steps (b) and (c) are repeated until the sections appear quite black; (e) the silver attached to structures other than the Golgi apparatus is removed with a ferricyanide/thiosulphate bleach; (f) the section is ‘toned’ with gold chloride, fixed in thiosulphate, and washed thoroughly; (g) the section is dehydrated, cleared, and finally mounted in Canada balsam, DPX, or similar media. Results: Golgi-apparatus, black; connective-tissue fibres, black; axons, grey to black; everything else is light grey or colourless.
3. A tentative hypothesis is advanced to explain the results obtained.
4. The following advantages are claimed for the new method: the cytoplasmic reticulum thus blackened resembles that seen in living neurones with the interference microscope; special methods of fixation are not required; the cytoplasmic reticulum of given cells can be studied before and after silvering; and serial sections of the same piece of tissue can be used for histochemical purposes.
Experiments on the Action of Mordants: I. ‘Single-bath’ Mordant Dyeing
Authors: Baker John R. 
Published: April 2021

ABSTRACT
Aluminium sulphate was chosen as the simplest mordant, and purpurine (1,2,4-hydroxyanthraquinone) as the simplest dye suitable for use in experiments with mordants.
It was shown by a series of experiments that a solution containing about 16 atoms of aluminium to each molecule of purpurine has special properties. A section already dyed with an aluminium/purpurine solution till chromatin is dark and cytoplasm lightly tinged, is in equilibrium with such a solution : that is to say, it neither takes up more dye nor loses any part of what it already holds. If the proportion of dye to mordant is increased, the section will take up more of the dye ; if the proportion of the mordant to the dye is increased, the section will lose part or all of the dye it held.
The experiments described in the paper, taken in conjunction with existing knowledge of the behaviour of aluminion ions in solution and of their capacity to form chelate compounds with anthraquinonoid dyes, afford a basis for the following theory of single-bath mordant dyeing by aluminium/purpurine.
One purpurine ion chelates with one hydrated aluminium ion to form a complex ion with double positive charge; this is attracted to sites of negative charge in the tissues, such as the phosphoric groups of the nucleic acids. Electrostatic attraction is replaced by covalent bonds, resistant to solution by neutral ethanol. In extraction (‘differentiation’) by the mordant, the dye partitions itself between the tissue/mordant complex on one hand and the dissolved mordant on the other.
An Electron Microscope Study of Bacteria in the Oocytes and Follicle Cells of Blatta orientalis
Authors: Gresson R. A. R. , Threadgold L. T. 
Published: April 2021

ABSTRACT
The bacteria present in the oocytes and follicle cells of Blatta orientalis Linn, were studied by means of electron microscopy. Bacteria are present in the follicle cells surrounding young oocytes, from where they invade the peripheral ooplasm. Each bacterium in an oocyte soon becomes surrounded by a system of membrane-like structures that form an outer covering. Later the bacteria congregate at the poles of the oocyte. An oval body was visible in one electron micrograph; this probably represents a stage in the life-history of the organism.
Tropical Ester Wax 1960
Authors: Steedman H. F. 
Published: April 2021

ABSTRACT
A modification of the standard ester wax 1960 is given which enables sections to be cut at a room temperature of 170 to 37° C (62·6° to 98 6° F). The melting-point of tropical ester wax is 50° C. Ribboning and flattening of sections is good, from 1 to 10 p.
The Structure and Mode of Functioning of the Reproductive Organs of Tritonia hombergi (Gastropoda Opisthobranchia)
Authors: Thompson T. E. 
Published: April 2021

ABSTRACT
Routine observations on Tritonia hombergi Cuvier dredged from an area off the south coast of the Isle of Man indicate that the species has an annual life-cycle similar to that of many dorid nudibranchs.
The ovotestis communicates with the anterior genital mass through numbers of collecting tubules which unite to form a stout hermaphrodite duct. This duct functions as a vesicula seminalis in adult specimens; spermatozoa stored here are physiologically immature. The hermaphrodite duct bifurcates to form male and female ducts; the region of the bifurcation forms a valve ensuring that oocytes shall not enter the purely male regions of the genital system during oviposition. The male duct is the glandular and muscular vas deferens which connects with the base of the protrusible penis. The oviduct opens into the lumen of the mucus-gland. A region of convoluted tubules close to the point of the opening of the oviduct into the mucus-gland is the albumen-gland. The bursa copulatrix is a blind tubular invagination of the lateral body-wall which in mature specimens stores spermatozoa received at copulation. There are thus three external genital openings.
Copulation is almost invariably reciprocal, the penis of each individual being inserted into the bursa copulatrix of the other. Secretions from the glandular linings of the bursa and of the vas deferens render spermatozoa exchanged at copulation physiologically mature; they are active and capable of fertilizing oocytes.
At oviposition oocytes are expelled from the ovotestis and transported by cilia to the main hermaphrodite duct. They then travel (through the dense masses of spermatozoa in this duct) along a narrow longitudinal ciliated tract of lining epithelium; this phenomenon was clearly observed in vivisected individuals. At the hermaphrodite valve the oocytes are deflected into the oviduct and are carried by cilia into the mucusgland. In the lumen of this organ they meet active ‘foreign’ spermatozoa which have made their way from the bursa copulatrix. The oocytes and spermatozoa are now conducted along a tortuous predetermined ciliary path through the albumen-gland (where the primary egg-cases are secreted and where fertilization occurs), and then through the peripheral tubules of the mucus-gland (where successive mucous coats are added). The completed egg-string is expelled through the external female aperture and forms a ribbon which is attached to the substratum by pressure of the parent’s foot upon it. Active spermatozoa may be observed moving within the primary egg-cases for some days after oviposition.
A Morphological and Histochemical Study of Oogenesis in the Gall-fly Cynips folii
Authors: Kraińska M. 
Published: April 2021

ABSTRACT
In the ovariole of Cynips, cell groups that have arisen in the initial period of oogenesis, presumably from one gonial cell, differentiate into the oocyte and 12 nurse cells (which constitute the nutritive chamber). The oocyte remains connected with the nurse cells by a strand of cytoplasm; the whole group acts as a physiological unit till the completion of vitellogenesis. Ribonucleoproteins are synthesized in the nurse cells and transmitted to the oocyte. The latter produces no detectable RNA.
There is no morphological evidence of any interchange of material between the nuclei or nucleoli and the cytoplasm of the oocyte or nurse cells.
Protein yolk components appear in the oocyte around the RNA inflow from the nurse cells. They associate with mucopolysaccharides, which appear in the same territory, to form carbohydrate-protein complexes. The synthesis of lipid yolk starts in the posterior part of the undifferentiated cell group and occurs subsequently only in the oocyte.
Nurse cells never penetrate inside the oocyte in normal undamaged ovarioles. They shrink and disintegrate outside the ovariole after completion of their life-cycle.
The anterior part of the oocyte develops into the egg pedicel with a terminal extension in which most of the glycogen of the cell is accumulated; the protein spheres in this extension are different from the protein yolk of the main part of the oocyte. The precursors of these protein spheres arise in the cytoplasm of the common cell group before the onset of yolk formation.
The function of the follicular epithelium is secretion of the egg envelope, which is of epicuticular nature. The penetration of material from the haemolymph to the oocyte occurs mainly through the cells of the nutritive chamber. The contribution of the follicular epithelium to this process seems to be of minor importance, at any rate in the early stages.
A Cytological and Histochemical Study of the Stria Vascularis of the Guinea-pig’s Ear
Authors: Chou John T. Y. 
Published: April 2021

ABSTRACTThe cells of the stria vascularis of the guinea-pig have been studied morphologically and histochemically. The stria vascularis consists of three layers of cells with bloodcapillaries. Apart from some yellowish pigments, the only cytoplasmic inclusions seen in the living cells and in the fixed materials are numerous rod-shaped mitochondria and spherical lipid globules. The mitochondria are about 1 ·5; μ in length with a diameter of 0 ·8; they contain phospholipid. The lipid globules are about 1 ·0 μ to 1 ·5 μ in diameter; they contain phospholipid and a small amount of cerebroside.The cytoplasm of these cells contains a small amount of diffused phospholipid and cerebroside.
The Nerve-net of Metridium senile: Artifacts and the Nerve-net
Authors: Batham E. J. , Pantin C. F. A. , Robson E. A. 
Published: April 2021

ABSTRACT
The present paper follows an account of the structure of the nervous system of Metridium, senile (L.). Conflicting statements about the actinian nervous system in the earlier literature made it necessary to assess the results of previous workers critically. Several of their methods have now been repeated and compared with our results after using more specific techniques. The criteria for distinguishing nerve-cells from non-nervous elements in actinians are discussed. Mesogloeal fibres, amoebocytes, nematocyst threads, and muscle-fibres may on occasion be confused with nerve-cells, and deteriorating nerve-cells may also have a misleading appearance. Gross artifacts may be reduced by the use of special staining methods, and on the basis of this work the results of several earlier authors have been re-interpreted. It is concluded that the nervous system in the mesenteries and column of Metridium follows the epithelial layers and does not penetrate the mesogloea.
A Comparative Histological Study of the Tube-feet of two Regular Echinoids
Authors: Nichols David 
Published: April 2021

ABSTRACT
The histology of the suckered and peristomial tube-feet of the two regular echinoids Cidaris cidaris (Cidaroida) and Echinus esculentus (Diadematoida) is described; of these orders the Cidaroida is the more primitive. The suckered tube-feet of both urchins have a connective-tissue sheath the fibres of which branch extensively before inserting at the disk, and in which are embedded numerous spicules, enlarged distally to form a supporting skeleton of the disk. A series of levator muscles, separate from the retractors of the stem, raise the centre of the disk during adhesion, and this activity also probably squeezes mucus from a series of glands opening at the disk surface. In Cidaris a second series of glands, goblet cells in the disk epithelium, are operated by special short muscle-fibres running between them; these cells and the muscles are absent in Echinus. In Cidaris sensory cells are apparently scattered over the entire disk surface, whereas in Echinus they appear to be mainly concentrated in a ring round the disk periphery. The peristomial tube-feet of both urchins are not suckered; the levator muscles are absent, and the disk, supported by a less complex calcareous skeleton, contains mainly sensory cells and mucous glands. The possible derivation of the diadematoid, clypeasteroid, and spatangoid tube-foot plans from that of the cidaroid is discussed. The differences in ornamentation of the regions of the test which bear the tube-feet are discussed functionally, the main conclusion being that a tube-foot whose activity is at all angles to the test requires a wider base than one whose activity is mainly perpendicular; this is shown to be the case in spatangoids also. A respiratory function for Stewart’s organs in the Cidaroida is suggested.
Histological Changes in the Gut of Mitopus morio (Phalangiida) during Protein Digestion
Authors: Phillipson John 
Published: April 2021

ABSTRACT
The description of the gross morphology of the gut of Mitopus morio agrees with Kastner’s (1933) description for Opilio parietinus De Geer except that 4 pairs of lateral openings lead from the mid-gut into the diverticula and not 3 as previously recorded. The two main types of diverticular cell in M. morio are digestive and secretory. There is thus agreement with the structures present in spiders, scorpions, and other harvest-spiders. The mid- and hind-gut epithelia both possess a single cell-type. That of the midgut is absorptive and digestive, whereas that of the hind-gut secretes a membrane round the faeces to form a pellet. During protein metabolism some extracellular digestion occurs in the lumina of the diverticula and mid-gut. The necessary enzyme or enzymes are produced by the diverticular secretory cells and are replenished within 24 h. Extracellular digestion is followed by partial or complete intracellular digestion in the diverticular digestive cells, which then cut off either digestive cell apices, containing partially digested protein globules, or digestive cell faeces which contain excretory material. Further digestion of the protein globules of the digestive cell apices occurs in the mid-gut cells, which then produce mid-gut cell faeces that are voided with the digestive cell faeces and indigestible food remnants.
A Comparison of the Nervous Systems of two Sea-Anemones, Calliactis parasitica and Metridium senile
Authors: Robson Elaine A. 
Published: April 2021

ABSTRACT
The properties of the actinian nervous system are known mainly from physiological experiments on Calliactis parasitica (Couch), and from histological work on Metridium senile (L.). The structure of the nerve-net in the mesenteries of Calliactis is now shown to resemble in general that in Metridium. Methylene blue stains a network of bipolar cells over the retractor muscle, together with sense-cells, and unlike Metridium, multipolar nerve-cells. The nerve-net over the radial surface of the mesentery is similarly much sparser. The distribution of nerve-cells and sense-cells in the column also resembles that in Metridium.
Experiments on Metridium show that as in Calliactis, the rate of conduction in the mesenteries is greater than in other parts of the anemone. The column, including the sphincter region, conducts more slowly. It is thus shown that the presence of a well- developed nerve-net over the retractors is associated with the development of fast tracts in the through-conduction system, and of rapid, facilitated contractions of the retractor muscles, in both species of anemone.
Structural Changes in the Gills, Intestine, and Kidney of Etroplus tnaculatus (Teleostei) adapted to different Salinities
Authors: Virabhadrachari V. 
Published: April 2021

ABSTRACT
There is an increase in the number of the so-called ‘chloride cells’ in the gill epithelium with increasing salinity of the medium. In 75% and 100% sea-water the ‘chloride cells’ exhibit a change in structure, in that they become more granular and acquire an apical vacuole. There is also a general decrease in the number of mucous cells with increasing salinity of the medium of adaptation.
The glomerulus tends to become smaller in the fishes adapted to high salinity as compared to the fresh-water fish. There is also a deposition of pigment around the nucleus and an indication of some changes in the nucleus of the kidney tubule cells in fishes adapted to 100% sea-water.
In the intestine, adaptation to high salinities results in an increase in the nuclear size of the columnar epithelial cells, an increase in the number of flask-shaped cells, and a considerable increase in the thickness occupied by the tunica propria.
Lipids in the Human Oocyte
Authors: Guraya Sardul Singh 
Published: April 2021

ABSTRACT
The cytoplasm of the human oocyte contains two categories of lipid bodies that are here called and Lt for the sake of brevity. The Lj granules and spheres consist of phospholipids and triglycerides. The La bodies occur as aggregations of granules or fenestrated plates, consisting of phospholipids. The yolk granules are made up of phospholipids, proteins, and carbohydrates.
Principles and Technique of Fluorescence Microscopy
Authors: Young M. R. 
Published: April 2021

ABSTRACT
Interest in fluorescence microscopy has greatly increased in recent years. Technical considerations have to some extent prevented even wider application of the various fluorescence techniques now available for microscopical study of biological specimens. This paper outlines the basic requirements for optimal image quality, for the benefit of biologists and others who may not be conversant with the optical principles involved. The central problem of illumination is reviewed in some detail, and an assessment given of the two methods in current use, namely the bright-field and dark-field systems. Ratios of fluorescent to activating light received by the objective aperture, given by the two systems, have been compared, and measurements have been made of their relative light-concentrating power.
Available light sources and their suitability for the excitation of fluorescence are discussed, with the problems of selecting appropriate light filters for use with the alternative systems of illumination.
It is concluded that the dark-field system has decided advantages in practice and in theory for the following reasons:
The dark-field condenser serves as an efficient primary filter, contributing to a black background and hence good contrast.
The equivalent focal length is less than that of the bright-field condenser and it concentrates energy in a smaller area; this compensates in part for the loss of energy inevitably caused by the central stop.
It permits the use of wide-band primary filters of maximum transmission because contrast in the fluorescent image is affected only by a weak superimposed dark-field image produced in the object-plane by scattered residual activating light passed by the primary filter. With blue-light activation the visible dark-field image is effectively eliminated by means of a weak blue-absorbing secondary filter.
The loss of contrast due to veiling glare is minimized.
A rational layout for fluorescence microscopy and methods for accurate alignment of the microscope in the vertical and horizontal positions are described. Factors influencing the choice of suitable objectives and eyepieces and some details of methods for mounting specimens are given.
The Connective-Tissue Sheath of the Nervous System of Locusta migratoria: an Electron Microscope Study
Authors: Ashhurst Doreen E. , Chapman J. A. 
Published: April 2021

ABSTRACT
The sheath is composed of an outer non-cellular layer, the neural lamella, and an inner layer of sheath cells. The neural lamella possesses a large number of collagen fibrils arranged in layers with differing orientations. The sheath cells are flattened on the inner surface of the lamella and the cytoplasm contains lipochondria, mitochondria, and small amounts of endoplasmic reticulum.