bluuebunny/crossref_metadata_2025_split huggingface dataset:
A further Account of the Spermatogenesis of Lice
Authors: Cannon H. Graham 
Published: April 2021

ABSTRACT
In 1919 the late Professor Doncaster and the present author investigated the gametogenesis of the lice Pe die ulus corporis and Pedieulus capitis. An account of this work was published during the following year (3). The cytology of the spermatogenesis was found to be so peculiar and in some respects unique, that it was decided to extend the work to other lice. At the time of his death Professor Doncaster was working on the gametogenesis of the horse-louse and the doglouse. The material collected by him together with his notes was handed over to me by Professor J. Stanley Gardiner.
Observations upon the Behaviour and Structure of Hydra.
Authors: Marshall Sheina 
Published: April 2021

ABSTRACT
The Hydras upon which the following observations were made were obtained from various sources, chiefly through the kindness of Dr. Monica Taylor, from the Convent of Notre-Dame. They were kept in covered, half-pint glass tumblers, in water from a large tank in which there was a fair quantity of weed and a variety of animal life (Isopods, Cladocerans, Planarians, &c.). This was used because the Hydra would not live for more than one or two days in tap-water. The water was-changed and the tumblers cleaned when necessary. This was about once a week in summer, as food-remains became foul very quickly then, but less frequently in winter. The water was never aerated artificially. The Hydras were fed on a culture of Daphnia twice a week, and the remains and excreta removed, as far as possible, the following day. Under these conditions the Hydras lived and remained healthy for months. Occasionally one or two, for no apparent reason, would decrease in size and finally degenerate and die, but in only one case was a whole tumbler attacked by a ‘depression period Even here a fair proportion remained healthy throughout. When well fed the Hydras budded actively. None of my specimens carried more than four or five buds at a time and the number was usually less.
Contributions to the Study of the Development of the Head in Heterodontus
Authors: Beer G. R. de 
Published: April 2021

ABSTRACTThe development of the skull of Heterodontus is described. There is no trace of an otic process. The tectum synoticum forms after the more anterior roofing. The efferent pseudobranchial artery is from the first dorsal to the trabecula. The afferent pseudobranchial artery is not the mandibular artery. Longitudinal bands of cartilage exist along the notochord but are probably not primary. The dorsal and ventral roots have moved forwards so as to be enclosed in cartilages. The olfactory nerve is subdivided into two, which subdivisions do not correspond with the subdivisions of the olfactory sac. The neural crest contributes to the terminalis, which shows one ganglion.
On the Development of the Male Genitalia and the Efferent Genital Ducts in Lepidoptera
Authors: Raj Mehta Dev 
Published: April 2021

ABSTRACTA general account of the internal reproductive organs and the external genitalia and their development is given.The ‘penis lobes’ develop earlier than the ‘valvae lobes ‘, and independently of them.The tegumen is the modified ninth tergite. The tenth segment is visibly distinguished into a tergal and sternal part in the pupal stages, and the anal tube passes between the two sclerites. The uncus and the gnathos are dorsal and ventral processes respectively of the tenth segment. The anellus lobes develop as lateral processes of the ninth sternite on either side of the penis.The vasa deferentia during larval life do not extend beyond the eighth abdominal segment and lie in a latero-ventral position. They meet the extensions from the ectodermal ‘ductus ejaculatorius duplex’ during the last larval stadium.From the earliest caterpillar stage there exists a pair of ectodermal ducts formed by the differentiation of the epidermis on the ninth sternite. Towards the end of larval life they divide by constriction to form the accessory glands and the ‘ductus ejaculatory duplex’. At this stage they extend on either side to meet the vasa deferentia.The vesiculae seminales develop by distension from the region of junction between the vasa deferentia and the proximal portion of the ejaculatory duct.The ‘ductus ejaculatorius simplex’ arises as an ectodermal invagination between the pair of ‘penis lobes ‘during the final larval instar.It is established that, with the exception of the vasa deferentia, all the remaining elements in the efferent genital system are derived from the ectoderm.
Notes on the Structure and Development of the Female Genital System in Dasyneura leguminicola Lint. (Cecidomyidae-Diptera)
Authors: Metcalfe Margot E. 
Published: April 2021

ABSTRACT
Genitalia of an appendicular nature are absent in D. leguminicola, the terminal abdominal segments being modified to form a tubular retractile ovipositor. Apart from the ovaries and a portion of the paired oviducts, the efferent system is unpaired and ectodermal in origin. The gonopore is posterior to the ninth sternite, and is derived from the primitive spermathecal invagination as in the Coleoptera. The uterine rudiment is present during the early stages of development, but later becomes closed over, discharging its contents into the duct derived from the spermathecal rudiment.
The Formation of Melaniridosomes in healing wounds of Haemulidae
Authors: Smith George Milton 
Published: April 2021

ABSTRACT
The earlier studies of the pigment cells of fishes by v. Siebold (1863), Pouchet (1876), Leydig (1895), were followed by a long series of important investigations by Ballowitz (1893-1924) upon which a large part of our present knowledge of the complicated morphology of the teleost skin rests. More recently, information on this subject has been extended by the work of Kurz (1920), Becher (1924), Schnackenbeck (1925), Kann (1926), Jost (1926), Panu (1929), Graupner and Fischer (1933).
Note on the Behaviour of certain Cell Inclusions during Mitosis in Tenthredinidae.
Authors: Peacock Professor A. D. , Greenshields F. 
Published: April 2021

ABSTRACT
Four conspicuous rounded bodies, lying symmetrically disposed, one on the surface of each quadrant of the spindle, have been found during the metaphase of blastoderm cells developed from the partheno-produced (male) eggs of Thri-nax mixta, a parthenogenetically arrhenotokous species of Tenthredinidae. During the process of cell division they ultimately form a single mass in a position formerly occupied by the centre of the spindle, and the material composing this mass streams out towards either pole and appears to be more or less equally shared between the two daughter cells. The movements of the inclusions appear to be due to changes in the form of the spindle. Their fate is unknown, as is their function. Such bodies and their behaviour do not appear to have been recorded before, but in certain respects they behave like aggregations of thread-like cell inclusions in Stenobothrus lineatus which Bělařcalls mitochondria; that they are mitochondrial is suggested from the technique which revealed them. It is suggested that such bodies might easily be mistaken for sex chromosomes.
Cleavage of Blastomeres in the Absence of Nuclei
Authors: Gross F. 
Published: April 2021

ABSTRACT
In the following pages a brief account is given of observations which touch upon two much discussed problems: (1) are eggs or blastomeres capable of division if deprived of the nucleus? (2) are divisions of blastomeres in the absence of chromosomes and spindles to be regarded as cleavage, and the product resulting from the divisions as corresponding to stages of normal development, in this case, to a blastula?
On the Occurrence of Living Forms in the Hot Waters of California
Authors: Edwards Arthur Mead 
Published: April 2021

ABSTRACT
In the May (1866) number of the ‘American Journal of Science’ were some notes by Prof. Brewer on the occurrence of living forms in the hot and saline waters of California, in which a slight error appeared, tending to mislead naturalists more particularly with regard to certain observations of mine. In the subsequent number for November Prof. Brewer inserted a note making a correction in this matter, but, as the subject is one of importance, I have taken the liberty of putting together a few notes relating thereto, and beg of you to insert them at your convenience.
Notes on some Algæ from a Californian Hot Spring
Authors: Wood H. C. 
Published: April 2021

ABSTRACT
Some time since Professor Leidy handed me for examination a number of dried Algæ, which he had received from Professor Seidensticker, by whose sister, Mrs. Partz, they had been gathered in the Benton Spring, which is situated in the extreme northern point of Owen’s Valley, California, sixty miles south-west from the town of Aurora. Afterwards a number of similar specimens came to me directly from Mrs. Partz by mail. The subject of life in thermal springs is one of so much general interest, especially in connection with that of spontaneous generation, as to induce me to make a very careful examination of the material and offer the results to the readers of this journal. In this connection the following extract from a letter of Mrs. Partz to her brother is very relevant:
A Quantitative Study of the Changes in the Cyto-some of Eggs of the Echinodermata during Early Cleavage
Authors: Pelluet D. 
Published: April 2021

ABSTRACT
An estimate of the changes in volume, fat, and mitochondria occurring in the early cleavage stages of Arbacia has been made. The volume fluctuates with each successive cleavage, but it is probable that there is no significant change until after the gastrula stage has been reached.
The number of fat-granules decreases steadily from the unfertilized to the four-cell stage, with a slight increase in the blastula.
The mitochondria show a slight decrease between the unfertilized and fertilized condition and a marked decrease at the four-cell stage, followed by a sharp increase in the blastula.
A preliminary investigation of another Echinoderm, Asterias forbesi, suggests that it differs considerably from that of Arbacia.
It is a pleasure to acknowledge the assistance of Dr. F. R. Hayes in several ways, and especially for checking many of the calculations.
The Direct Development of a New Zealand Ophiuroid
Authors: Fell H. Barraclough 
Published: April 2021

ABSTRACT
The first cleavage may be either equal, or markedly unequal; when it is equal the next segmentation affects both blastomeres ; when it is unequal the larger blastomere is believed to give rise to three cells, and the smaller remains undivided till the next cleavage. At the eight-cell stage there are two quartets of blastomeres. The upper quartet, micromeres, occupy the animal pole. The lower quartet, macromeres, occupy the vegetal pole. The blastula comprises micromeres and macromeres, and the blastocoel is small and becomes eccentric. No cilia are developed. The gastrula is formed by the shallow invagination of the macromeres, accompanied by an extensive process of epiboly affecting the micromeres. More marked epiboly of cells on two sides of the blastomere produces in the early stages two crests which later disappear. These may indicate a trace of bilateral symmetry. Epiblast comes to lie on solid mes-hypoblast. The archenteron is transient, and gives rise to no structures. The blastopore occupies the position of the definitive mouth. No larva ever forms, nor is there any vestige of a larval stage. The solid gastrula is converted into the adult by assuming a radial symmetry directly, with no intermediate bilaterally symmetrical form, unless the two epibolic crests are regarded as vestiges of larval symmetry. The podia appear as solid outgrowths, in which the hydrocoelic cavity develops by splitting. The definitive enteron appears as a split extending upward from the ventral surface through the solid hypoblast. The young ophiuroid leaves the egg before the appearance of the general body cavity, and moves about, but does not at first take food. The general coelomic body cavity and the perihaemal cavity develop by splitting in a mass of mesenchyme derived from the outer layers of mes-hypoblast. The formation of the skeletal system is delayed till the stage of between two and three arm-segments. The development of the skeleton follows closely that described for Amphiura squamata. The tooth is shown to originate independently of the torus angularis; its rudiments comprise nine symmetrically disposed spicules. The terminal plate arises later than the radials, and has a distinctive ‘primitive structure’. The spine is shown to have a different development to that of the tooth, and therefore would seem to have no connexion with the latter in phylogeny or ontogeny. It is suggested that the aberrant early stages are to be correlated with the retarding effect of the yolk mass present in the egg during ontogeny. The aberrant features may have had a different origin in phylogeny. It is suggested that the simultaneous appearance in ontogeny of homologous organs situated at equal radial distances from the centre is to be explained in terms of hormonie activity. It is concluded that evolution has considerably affected the early ontogeny without leaving its mark on phylogeny. The adult thus conforms to its class, the young form does not.
The ‘Dorsal Organ’ of the Embryo of Campodea
Authors: Tiegs O. W. 
Published: April 2021

ABSTRACT
In his well-known work on the embryology of apterygote insects, written over forty years ago, Uzel recorded the presence of a ‘dorsal organ’ in the embryo of Campodea staphylinus. It was described as a circular thickening of the provisional body-wall, located in a median dorsal position immediately behind the developing head, but devoid of any very distinctive structural features. Like the problematical ‘dorsal organ’ (pre-cephalic organ) of collembolan embryos it was found to be a purely embryonic structure, and disappeared without a vestige before the larva left the egg. Its function was unknown.
Micro-anatomical Studies on Asellus
Authors: Needham A. E. 
Published: April 2021

ABSTRACT
The micro-anatomy of the autotomy mechanism in the thoracic appendages of Asellus is described; it shows considerable resemblance to that of Astacus, except in size. The fifth thoracic pair of appendages do not autotomize in the mature male Asellus. This depends on a very small anatomical difference, the closure of a fissure which is present in the exoskeleton of normally autotomizing limbs. The method of autotomy is inferred from observations, and from the arrangement of the muscles of the limb. The micro-anatomical changes which accompany the very rapid expansion of the oostegites in the female Asellus, are described. A system of ‘microtrichia’, probably homologous with that of insects, is described in Asellus and in certain other Crustacea. Its probable function is indicated. The pattern of pigmentation in Asellus is largely determined by the muscular system of the body, but is, nevertheless, probably adaptive. The pattern in other Isopoda is similarly determined but may be modified. Certain unrecorded differences between Asellus aquaticus and Asellus (Proasellus) meridianus are enumerated.
Cytochemical Differentiation between the Pentose and Desoxypentose Nucleic Acids in Tissue Sections
Authors: Sanders F. K. 
Published: April 2021

ABSTRACT
Animal tissues contain two types of nucleic acid: the desoxypθntose, or thymo-, nucleic acids whose distributionis confined to the nucleus; and the pentose, or yeast, nucleic acids which can occur in both nucleus and cytoplasm. For many years.it has been possible to identify desoxypentose nucleic acid by means of the Feulgen reaction, although, as has been frequently pointed out (Lison, 1936; Stowell, 1943), this must be carried out under carefully standardized and controlled conditions if its results are to be reliable. No corresponding test for pentose nucleic acids existed until Brachet (1940, 1941) showed that it was possible to identify pentose nucleic acids by comparing sections stained with basic dyes with other sections similarly stained following treatment with a pancreatic extract containing the enzyme ribonuclease. Therefore a distinction between the two types of nucleic acid may be made by applying both the Feulgen and Brachet tests to the same material. However, since the stains used in the two cases are different, and one set of sections is subjected to acid hydrolysis and the other is not, it may be difficult to relate the two cytological appearances to one another.
The Effect of Removal of the Anterior Lower Sac on the Lateral Appendix in the Embryonic Olfactory Organ of Kaloula Borealis (Barbour)
Authors: Tsui Chi-Lan 
Published: April 2021

ABSTRACT
The removal of the anterior lower sac from the embryonic olfactory organ of Kaloula borealis produced two different and opposite effects on the lateral appendix. In larvae 11-27 mm. in length the excision of the sac had a harmful effect and hastened the degeneration of the appendix. When the same operation was made on the larvae 28-38 mm. in length, however, the degeneration of the appendix was retarded. Early removal of the sac had also deleterious effect on the olfactory placode but did not, within the experimental period, influence its normal course of development.
Since the experimental animals made only limited growth in the laboratory, the later effects of the removal of the anterior lower sac remain unknown. It is planned to rear experimental larvae under more natural conditions.
A Simple Method for Cutting Sections in the 0·5 to 1 μ Range, and for Sections of Chitin
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
Tissues fixed and stained with osmium/ethyl gallate often require sectioning at 0·5 to 1 µ. In the method described they are double-embedded in agar and ‘ester wax’ (Steedman), cut on a film of water on the coverslip, and mounted in gum containing ethyl gallate. Prepared safety razor blades are recommended. This method is useful also for cutting serial sections of insect cuticle.
The Blood-cells of the Ascidian, Phallusia mammillata
Authors: Endean R. 
Published: April 2021

ABSTRACT
The structure, histochemistry, and histogenesis of the blood-cells of Phallusia mammillata (Cuvier) have been investigated.
Primitive lymphocytes give rise, by a series of transition stages, to vanadocytes, pigment cells, phagocytes, and cells with acidic vacuoles. There is evidence that most of these cells must eventually leave the blood-stream. During the development of each cell type, RNA appears to be released from the nucleus, and there is a progressive reduction in nuclear volume.
Ninety-eight per cent of the total number of blood-cells are vanadocytes or their precursors. Each vanadocyte contains a number of globules. Each globule has a central core enclosed by a surface membrane containing compound lipid. In the core, a vanadium compound is associated with H2SO4, protein, and carbohydrate material, which may be the precursor of the tunicin of the test. Part of the carbohydrate material is in a dispersed form and can be hydrolysed with 2N H2SO4. The remainder is in the form of birefringent grains which resist hydrolysis, and appears to be a very insoluble polysaccharide.
Those lymphocytes that are destined to form vanadocytes develop vacuoles in their cytoplasm initially. In these vacuoles, which are ringed with granules that are probably mitochondria, granular material capable of reducing OsO4 and AgNO3 is formed. The vacuoles in each cell then unite to form one large vacuole, and refractile granules appear in the perinuclear cytoplasm. These granules then move out from the nucleus in the cytoplasm peripheral to the vacuole. Each refractile granule is then enclosed in a subspherical compartment in which protein material is formed. As the compartments are transformed into the globules of vanadocytes, acid, PAS-positive material, and a vanadium chromogen with reducing properties appear.
The pigment cells contain melanin and oriented submicroscopic crystallites.
p-toluenesulphonic acid as a fixative
Authors: Malm Mignon 
Published: April 2021

ABSTRACT
p-toluenesulphonic acid in aqueous solution is introduced to histologists and recommended for fixation of the central nervous system by a three-step procedure: flushing the blood-vessels with a saline solution, filling the vessels with the fixative, and delaying the autopsy. With rats and guinea-pigs as test objects, a solution of at least 0·5 M gave excellent results, as evidenced by the minimum of cellular shrinkage, the absence of perivascular and perineuronal spaces, and the clarity of cellular membranes and basiphil material. The neurones, neuroglia, microglia, and blood-vessels were well defined when stained by conventional histological techniques. Cytological details became more prominent because the tissue had shrunk less than in routine preparations. The acid is non-volatile, colourless, pleasant to handle, and low in price.
The actions of enzymes on lampbrush chromosomes
Authors: Macgregor H. C. , Callan H. G. 
Published: April 2021

ABSTRACT
The chromomeres of lampbrush chromosomes of Triturus cristatus are Feulgen-positive; they therefore contain DNA. After removal of their DNA in boiling trichloracetic acid, the chromomeres stain with fast green at alkaline pH; they therefore contain basic protein. The lateral loops are Feulgen-negative; they stain with toluidine blue at acid pH, but much less intensely following RNase digestion; they therefore contain RNA. The spheres of chromosomes V and VIII do not contain RNA.
Unfixed lampbrush chromosomes retain a life-like appearance in 0·07 M K/NaCl at pH 6·2; in this medium the nuclear sap disperses. As pH is raised to 8·5 the matrices of lateral loops dissolve but chromosome axes remain unbroken. Above pH 8·5 lampbrush chromosomes dissolve. As pH is lowered from 6·2, at between 5·8 and 5·4 coagulation occurs. If pH is rapidly reduced still further, a persistent relaxed condition sets in between 2·5 and 2.
In concentrations of K/NaCl above 0·5 M lampbrush chromosomes dissolve. Lateral loop matrices dissolve in 0·25 M K/NaCl but chromosome axes remain unbroken. In concentrations of K/NaCl below 0·05 M lateral loop matrices dissolve, but even in distilled water chromosome axes remain unbroken.
Trypsin at pH 6·2 and at pH 7·8 strips the matrices from lateral loops and occasionally breaks matrix fusions. It causes chromomeres to swell and coalesce, but fails to break chromosome axes. The action of ‘pan-protease’ resembles that of trypsin in all respects.
Pepsin at pH 6·2 strips the matrices from lateral loops, but does not destroy chromomeres. At low pH peptic digestion is slow: the enzyme is attacking coagulated chromosomes; but if peptic digestion precedes a lowering of pH the overall outcome is a rapid solution of loop matrix, and under these conditions matrix and sphere fusions are broken. If trypsin or ‘pan-protease’ digestion precedes a lowering of pH there is a similarly rapid solution of loop matrix; thus the action is not specifically referable to pepsin. Under no conditions does pepsin break the axes of lampbrush chromosomes.
RNase at pH 6·2 strips the matrices from lateral loops; this action is detectable at extreme dilution. RNase does not destroy chromomeres, nor does it break chromosome axes. If tryptic digestion follows RNase digestion this too fails to break chromosome axes.
Unlike the proteolytic enzymes and RNase, DNase at pH 6·2 breaks the fibril between adjacent chromomeres, and it also breaks the axes of lateral loops.
Contrary to Mazia’s experience with salivary gland chromosomes, versene does not break the axes of lampbrush chromosomes even when applied in media of low electrolyte concentration.
These results indicate that uninterrupted fibres of DNA run throughout the lengths of lampbrush chromosomes.
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