bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Primitive Streak and associated structures in the Marsupial Bettongia cuniculus
Authors: Kerr T.
Published: April 2021

A series of ten blastocysts of Bettongia cuniculus is described, covering a range of development from the appearance of the primitive streak to the establishment of the medullary plate. In the first blastocyst there has appeared a small area of ectodermal thickening between the centre of the embryonal area and its periphery, and it is suggested that this is the primordium of the primitive streak. In the second blastocyst a very young streak is present which does not reach either to the middle or to the periphery of the area, and whose centre is in nearly the same position as that of the first blastocyst. At its maximum the streak stretches about two-thirds of the way across the embryonal area. A groove develops down its middle and active mesoderm production occurs from its edges. The mesoderm forms an approximately oval area round the streak, and extends into an extra-embryonal position first posteriorly and then laterally. At the anterior end of the streak appears a broader, thicker region of similar but looser tissue, the primitive knot; from here grows forward the head-process in the usual way, and at the same time the endoderm underlying these two structures fuses with them. No lumen is present in the head-process at any stage. The originally circular embryonal area elongates until it becomes somewhat pear-shaped, and later it constricts in the middle. The thickened ring of endoderm at the edge of the embryonal area, the annular zone of proliferation of Hubrecht, is distinguishable at the time of appearance of the primitive streak; but the second thickened area, the prochordal plate, does not appear until the streak is well established, and except in its earliest stages is hard to delimit owing to its relative thinness and to the closely investing mesoderm which soon covers it. The question of mesoderm production from these sources is discussed, and it is concluded that while such does in fact occur in this form it is quite insignificant in amount as compared with that produced from the sides of the primitive streak. In the last stage described the medullary plate and chorda are well established, and the importance of the primitive streak is diminishing. Mesoderm, whose production now appears to be occurring chiefly by division of pre-existing mesoderm cells, is very much more abundant, and can be divided into three parts: thick sheets extending from near the axial line to beyond the edge of the medullary plate, condensations in which the pleuro-pericardial coelom is appearing anteriorly, and vascular mesoderm in which blood-vessels are forming. Blood-islands are not present within the vessels, and apparently are represented by groups of cells between the vessels. A well-formed prochordal plate is also present.
The Later Embryology of Rhodnius prolixus
Authors: Mellanby Helen
Published: April 2021

The development of the external features of the embryo from the time at which the germ-layers are laid down until hatching is described. The fate of the embryonic membrane is followed, and the formation of a ‘cuticular’ layer round the whole embryo produced by the glands which result from the modification of the first abdominal appendages (pleuropodia). The central nervous system is produced in a similar manner to that of other insects. Two parallel longitudinal rows of neuroblasts separate from the dermatoblasts and give rise to the longitudinal nerve-cords. In between them is the neural groove, and cells dorsal to the neural groove produce a median cord. Neuroblasts in the protocerebral, antennary, and pre- mandibular segments form the supra-oesophageal nerve-mass, and those in the mandibular, maxillary, and labial the sub- oesophageal mass. At first three thoracic and eight abdominal ganglia are formed. Later concentration occurs, and by 18 days all the ventral ganglia are located in the thorax, the metathoracic ganglia being particularly large. The sympathetic nervous system arises from the dorsal wall of the stomodaeum. The corpus allatum originates as a pair of ectodermal cellmasses which appear to be invaginated from the maxillary segment. The ectodermal invagination to form the tentorium, glands, and spiracular system is described. Oenocytes appear previous to the ectodermal cells producing their cuticular layer. They become more numerous and much smaller after cuticle formation. The fore- and hind-gut develop normally. The Malpighian tubules are developed from ectoderm. The mid-gut arises in three parts, and the yolk becomes restricted to the middle part in the late embryos. From the mesoderm the usual structures are derived. Musculature of limbs and body is of two distinct kinds. The heart, fat-body, and splanchnic muscles are derivatives of the mesoderm. The germ-cells are defined before the germ-band invagi- nates. Later they are to be found, round the coeloms of the posterior abdominal segments. They migrate anteriorly and form complete gonads 10 days before hatching. The structure of the head of Rhodnius supports the orthodox view that the head of insects is composed of six segments. Evidence from the development of Rhodnius suggests that the insect labrum represents a pair of appendages. Time-table of development at 21° C. and 90 per cent, relative humidity.
Internal Anatomy of a Caddis (Hydropsyche colonica)
Authors: Glasgow J. P.
Published: April 2021

The internal anatomy of both larval and adult Triohoptera has been very little investigated and but fragmentary accounts exist. For the present study the common New Zealand caddis Hydropsyche colonica McL. was selected both on account of its conveniently large size and because it could readily be obtained in large numbers. The internal anatomy of the larva is described in detail and a preliminary account given of the internal anatomy of the adult, together with some notes on metamorphosis.
On New Species of Diatomaceæ, being a Reply to Mr. Kitton’s Remarks
Authors: O’meara Rev. E.
Published: April 2021

In reply to Mr. Kitton’s animadversions on my two papers recently published in the ‘Microscopical Journal,’ I venture to make a few remarks. To resent the temper of his criticisms could subserve no useful purpose, and therefore I refer to it merely to express my sincere regret that the intrinsic value of the remarks should have been depreciated by the tone in which they have been expressed. It is not unnecessary to say that I have been for very many years devoted to the study of the Diatomaceæ of Ireland, and have carefully examined many thousands of gatherings made by me, in all parts of the country and at all seasons, and have never attempted to publish any forms as new until the Arran dredgings of Dr. E. Percival Wright were placed by him in my hands. I do not make this statement of facts for the purpose of arrogating to myself a right to speak on the subject with an authority equal to that which Mr. Kitton has assumed, but of vindicating myself from the charge of being a novice in the matter, and of being affected with the disease usually known as the cacoethes scribendi, which his observations not very graciously suggest.
On certain Butterfly Scales characteristic of Sex
Authors: Wonfor T. W.
Published: April 2021

Nearly every one who has worked with the microscope and turned his attention to the scales of insects (especially the Butterfly tribe) has perhaps been struck with the great variety of form to be found not only in different butterflies, but on the under and upper side of the wings of the same insect. If, too, an attempt has been made to find in the “whites “or “blues “the scales described in all works on the Microscope, as found on certain members of each group, he has undoubtedly met with disappointment, especially if he has looked where our standard works tell us they are to be found. Thus, in the case of the azure blue (Polyom- matus argiolus), we meet with instructions tending to mislead ; thus in the ‘Micrographic Dictionary,’ under “Poly-ommatus,” p. 564, we read—” The scales upon the under surface of the wings of P. argiolus and P. argus have been proposed as test objects. They are of two kinds—one resembling in structure the ordinary scales of insects, the other of a battledore form.” Again, under the head of “Pontia,” p. 571 :—” The form and structure of certain scales existing upon the under side of the male is curious.” Now, any inquirer looking, in either case, in the situations named, will undoubtedly not find them, for the simple reason that these particular scales are never found on the under side.
Histological Demonstrations for the Use of the Medical and Veterinary Professions
Authors: Harley George , Brown George T.
Published: April 2021

We ought to have noticed this book earlier, but have put it aside from quarter to quarter in the hope of being able to write such a notice of its contents as its value and importance demands. Press of other matter has, however, prevented this, and we now feel that we ought not to allow another issue to pass without introducing it to our readers. For many years Dr. Harley has been in; the habit of giving a course of physiological demonstrations at University College. “The observation of the facility with which objects were prepared for examination in the presence of the class, and the readiness with which the directions of the demonstrator were comprehended and carried into effect by the students,” suggested to Mr. Brown “the possibility of describing in an intelligible manner the method of instruction which was so successful in practice.” The volume thus commenced by the pupil has been superintended by the master, and a very valuable aid to anatomical research by the use of the microscope has been the result.
Address delivered by the Rev
Authors: Berkeley M. J.
Published: April 2021

Few points are of greater significance than those which touch upon the intimate connection of animal and vegetable life. Fresh matter is constantly turning up, most clearly indicating that there are organisms in the vegetable kingdom which cannot be distinguished from animals. The curious observations which showed that the protoplasm of the spores of Botrytis infestans (the potato mould) is at times differentiated, and ultimately resolved into active flagelliferous zoospores, quite undistinguishable from certain infusoria, have met their parallel in a memoir lately published by MM. Famintzin and Boranetzky, respecting a similar differentiation in the gonidia of lichens belonging to the genera Physcia and Cladonia. It is, however, only certain of the gonidia which are so circumstanced; the contents of others simply divide into motionless globules.
The Development of the Serpulid Pomatoceros triqueter L
Authors: Segrove F.
Published: April 2021

The larvae of Pomatoceros triqueter L. were obtained by artificial fertilization and reared through metamorphosis and for several months afterwards. Larval development took three weeks in summer, and about the same time in winter when the temperature was maintained at 65° F. The eggs are small and give rise to typical trochosphere larvae with well-developed prototroch, metatroch, neurotroch, and feeding cilia, a spacious blastocoelic body-cavity and paired protonephridia. A head-vesicle and a conspicuous anal vesicle are also present. The right eye develops before the left. The larva is very active and grows rapidly at the expense of collected food material. Three setigerous segments arise simultaneously; a fourth is added prior to metamorphosis. The lateral collar-folds develop in two capacious pockets which arise by invagination of the body-wall behind the metatroch, the ventral collar-fold by outgrowth of the ventral body-wall. The rudiments of the thoracic membrane appear above the lateral collar-folds. Metamorphosis commences with the shrinkage of the locomotor apparatus, which leads to the exposure of the lateral collar-folds. The larva settles to the bottom and creeps about on its ventral surface by means of the neurotroch. The branchial crown arises as tripartite outgrowths on the sides of the head. The remaining tissues of the head, apart from the cerebral ganglion and eyes, are gradually resorbed. No tissue is thrown off. The neurotroch gradually disappears and is replaced by cilia on the dorsal surface. The worm begins to secrete a calcareous tube. The resorption of the head is completed and the mouth assumes a terminal position surrounded by the branchial crown. A fourth pair of filaments is added to the branchial crown. The dorsal pair of filaments develops into ‘palps’. The third filament on the left side is modified as the opercnhunn ; the remaining filaments develop pinnules. Further segments are added to the trunk. Those first added are of the thoracic type from the beginningThe eighth and succeeding setigers are of the abdominal type. The thoracic membrane gradually extends backwards to the posterior end of the thorax. The thoracic nephridia arise as a single pair of cells which give rise to the dorsal unpaired duct by outgrowth. The influence of the egg on the course of development is discussed. It is suggested: (u) that the small size of the egg is responsible for the active habits and protracted pelagic life of the larva; (b) that the mode of development of the collar is significant in that interference with the locomotor and feeding apparatus is thereby avoided; (c) that the general shrinkage which occurs at metamorphosis is related to a suspension of feeding activity in the period between the degeneration of the larval and the establishment of the adult feeding apparatus. The development of Pomatoceros is compared with that of the Serpulid Psygmobranchus and the Sabellid Branchiomma.
Tegumental Glands in the Cirripedia Thoracica.1
Authors: Thomas H. J.
Published: April 2021

In the Cirripedia the exo-skeletal integument consists of a thick layer of chitin with a thin superficial layer of cuticle. The cuticle agrees in properties with that of the Decapod Crustacea, and is also secreted by tegumental glands. Unicellular or compound glands, here first described, secrete the cuticle of the outer surface of the peduncle and capitulum; the labial and suboesophageal (‘salivary’) glands secrete that of the surface of the mantle cavity. In the Operculata the labial glands also secrete between moults, the cuticular material serving to entangle excess material which enters the mantle cavity and so assist in its rejection. The restriction of this accessory function to the Operculata may be correlated with their abundance in frequently turbid waters between tide-marks. The cement is identical in properties with the cuticle and the cement glands are regarded as modified tegumental glands. In the Pedunculata all the gland-cells regenerate after secretion. The labial and suboesophageal glands secrete only at the moult, in the other glands some of the cells are always active. In the Operculata secretion is confined to the moult apart from the secretion produced by the labial glands in connexion with rejection of particles. In the Operculata the cells of the cement glands degenerate after secretion, new cells developing from the walls of the duct. The specializations of the tegumental glands are correlated with the sessile habits of the Cirripedia.
The Development of the Pituitary of the Laboratory Mouse
Authors: Kerr T.
Published: April 2021

A description is given of the development of the mouse pituitary, with particular reference to some obscure points in the general embryology of the mammalian gland. The establishment of the neuro-ectodermal union of brain floor and stomodaeal roof precedes the appearance of Rathke’s pouch; its importance and the effects of external and internal factors on pouch formation and closure are discussed. It is considered that the process cannot be entirely due to mechanical influences and differential growth. The nervous lobe forms from a groove in the premammillary lamina which deepens and separates off. Later enlargement of the lobe is due to the reorganization of its cells, the appearance of fibres and a low but steady mitotic activity. The establishment of the lateral lobes and the blood supply, the distribution of mitoses, the development of processes from the proximal into the nervous lobe and other points are recorded.
Morphological observations on the fate of the Lateral Appendix in the embryonic Olfactory Organ of Rana nigromaculata
Authors: Tsui Chi-Lan
Published: April 2021

The anlage of the lateral appendix is formed from the dorso-lateral part of the olfactory placode in Rana nigro-maculata Hallowell. The lateral appendix, a blind sac, is formed when the dorsal lumen is differentiated in its anterior part. It increases in dimension as the olfactory placode further develops, but growth stops as soon as the anterior lower sac appears; it begins to degenerate when the medial nasal gland makes its appearance; and completely disappears towards the end of metamorphosis. Histological changes are described.
Monograph of Monera
Authors: Hackel Ernst
Published: April 2021

No nuclei or nucleus-like form could be perceived throughout the entire plasma body of the Protomyxa, nor contractile vesicles, if we understand by these, fixed organs which, although without a differentiated wall, still occupy definite positions in the body. Nevertheless, a great number of vacuoli were dispersed through the body, as well in the central mass as in the thicker branches. These appeared in the form of paler and more circular spots (fig. 11, 11 v) of different sizes, the largest of 0·03 mm. diameter. If one observed the same vacuole for a little time, its dilatation and contraction, and its appearance and disappearance could be distinctly observed. The former as well as the latter occurred very slowly, and required from about two to three minutes in the largest. By contraction the size of the vacuole became smaller and smaller, at last the clear space entir ely vanished; and it appeared as if the yellowish-red plasma had flowed together over it. If the place where the vacuole had vanished was watched, the vacuole would sometimes be seen to reappear slowly in the same place. A paler point appeared which became slowly larger and larger; it often exceeded its former boundary; another time it did not attain to it. But very often the vacuole remained invisible, and instead of this one, one or more new vacuoli appeared in other places, some near and some very distant. Sometimes in the place of a large vanished vacuole appeared a number (ten to twenty) of small vacuoli in the neighbourhood, either irregularly scattered or grouped in a circle over the place of the vanished vacuole. All this shows that the contractile cavities in the body of the Protomyxa are really vacuoli, i. e., wall-less cavities filled with a watery fluid in the middle of the homogeneous sarcode parenchyma, like those which also occur in many Rhizo-poda, Myxomycetæ, &c. They are also not true contractile vesicles such as occur in the true Infusoria (Ciliata),. and in some Amœhæ (e. g., A. quadrilineata). These latter are distinct and permanent organs, no matter whether they can be perceived to have an essential wall or not. True contractile vesicles always occupy precisely the same situations in the body, while the vacuoli appear and disappear here and there in the solid albuminous mass of the plasmaparenchyma. From this definition of vacuoli as distinguished from contractile vesicles it is naturally in no way disputed but that transitional intermediate forms between both occur. On the contrary, I consider it very probable that the contractile vesicles are developed from simple vacuoli phylogenetically (by natural selection).
On the Structure and Relationships of the Simple or Nucleated, and the Compound or Punctate Forms of Thalassicollidæ
Authors: Macdonald John D. , Surgeon Staff
Published: April 2021

Having perused Dr. W alii ch’s observations on the Thalassicollidæ in the ‘Annals and Magazine of Natural History ‘for February, 1869, I was induced to review my notes upon this subject, reaching as far back as 1852, the year just subsequent to that in which Professor Huxley’s excellent paper upon Thalassicolla was published; and though I can do little more than follow in his footsteps, yet the little material collected by me, as well as the accompanying figures (which are all original), may be acceptable to the students of the Protozoa. On the authority of Miiller, one of the two forms of Thalassicolla punctata, described by Huxley with great accuracy, has received the name of Sphærozoum, originally applied to something ambiguously described by Meyen, while the other, or that with fenestrated capsules, has been named Collosphæra. It would seem, however, that Thalassicolla nucleata has escaped the criticism of the bibliographers, being retained as the nominal representative of the family. I shall at once proceed to the description of the figures, making such comments as may be suggested in passing.
An electron-microscope study of the cytoplasmic inclusions in the neurones of Locusta migratoria
Authors: Ashhurst Doreen E. , Chapman J. A.
Published: April 2021

The cytoplasmic inclusions of the neurones of adult Locusta migratoria have been examined in the electron microscope. The mitochondria are easily recognized by their cristae and outer double membranes. Electron-dense inclusions, also with an outer double membrane but possessing numerous closely spaced internal lamellae in various orientations, are probably small lipochondria. Larger and more diffuse inclusions comprising crescent-shaped aggregates of loosely packed parallel lamellae and vesicles are present; the possible significance of these larger inclusions is discussed. A system of numerous small vesicles distributed throughout the cytoplasm makes up the endoplasmic reticulum.
The effect of temperature variation on the multiplication rate of two strains of Amoeba proteus
Authors: Hawkins Shirley E. , Danielli J. F.
Published: April 2021

The effect of temperature variation on the multiplication rates of two strains of Amoeba proteus and the corresponding heterotransfer strains obtained by transplantation of nuclei between the ‘ parent’ strains, has been studied. The two ‘parent’ strains multiply at a similar rate at 17° C but at different rates at 27° C and 11° C. The multiplication rates of the heterotransfers follow the cytoplasmic ‘parent’ at the low temperature and the nuclear ‘parent’ at the higher temperature.
Technical variations in Koelle’s histochemical method for demonstrating cholinesterase activity
Authors: Naik N. T.
Published: April 2021

Koelle’s histochemical method for demonstrating cholinesterase activity and the literature on its subsequent modifications have been reviewed. Experiments were carried out on the effect on the cholinesterase reaction of formaldehyde fixation, cold storage of tissues, pH of incubation solution, and progressive increase of incubation time. A series of experiments was also carried out in testing the specificity of substrates and selective inhibitors used in the Koelle method. Enzyme reaction was visualized by the ammonium sulphide method. As a result of these experiments the following technical desiderata have been established:

1. Fixation of tissues for 3 h in neutral formaldehyde solution at 4° C preserved the morphology of the tissues without appreciably affecting the histochemical results. Fixation for more than 6 h produced definitive inhibition of cholinesterases, especially AChE, in most tissues.

2. Periods of up to 24 h of cold storage before fixation had no appreciable effect on the cholinesterase reaction.

3. Incubation at pH values between 5· 0 and 6·0 produced neither significant diffusion artifacts nor loss of enzyme activity. Below pH 5 the AChE reaction was affected to a varying extent according to the tissues used.

4. B.W. 284 at a concentration of 5 × 10-5 M and ethopropazine hydrochloride at a concentration of 1 × 10-4 M were found to be suitable selective inhibitors for AChE and ChE respectively.

5. Visualization of results by means of ammonium sulphide method was found to be preferable to phase-contrast microscopy.
The fine structure of the body-wall and the growth of the cuticle in the adult nematode Ascaris lumbricoides
Authors: Watson B. D.
Published: April 2021

The fine structure of the body-wall in Ascaris lumbricoides was investigated by electron- microscopical techniques. The body-wall is composed of a cuticle, epidermis, and a single layer of muscle cells. The cuticle contains several layers: a superficial membrane, a cortex, the ‘fibrillar layer’, a matrix or homogeneous layer, 3 fibre layers, and a basal lamella. The cortex is divided into a homogeneous, external cortical layer, and a fibrous, internal cortical layer. The ‘fibrillar layer’ is a series of canals which extend from the inner part of the matrix layer to the cortex. The canals have distinct walls but no contents were demonstrated. No fibres or lamellae could, be detected in the matrix layer. The strands of the fibre layers and the basal lamella are formed from fine fibrils, less than 10 mμ in diameter. There is an inner system of canals that links the epidermis with the basal lamella and the fibre layers. The epidermis has a network of fibres, some of which attach the muscle cells to the cuticle. The muscle cell contains myofilaments of 2 types, an array of large filaments about 30 mμ in diameter, each surrounded by a number of smaller filaments about 5 to 7 mμ in diameter. Glycogen occurs in the epidermis and muscle and is identified as granules; there tends to be a clumping together of granules to form deposits about 100 mμ in diameter. External to the sarcolemma lies a connective tissue sheath which contains collagen, probably in the form of fibrillar and particulate material.

The cuticles of young adult Ascaris have a basic structure similar to that of the fully grown worms. During the growth of the adult worm the cuticle increases in volume, and this increase involves all the layers of the cuticle. The homogeneous or matrix layer increases in thickness more rapidly than the fibre layers, and both of these layers grow faster than the cortex. Ribonucleic acid is more abundant in the epidermis of young adults than in the fully grown worms and this is correlated with the development of endoplasmic reticulum and ribosomes. It is suggested that the extensive canal system in the cuticle transports materials to all layers of the cuticle.
Localization of Alkaline Phosphatase in Mammalian Bones
Authors: Lorch I. Joan
Published: April 2021

1. Adult mammalian bones may be decalcified in sodium citrate-HCl buffer at pH 4-5. The addition of Zn (10-4 M) prevents irreversible destruction of alkaline phosphatase which is, however, partially inactivated.

2. The phosphatase is subsequently reactivated by placing the tissues in 1 per cent, sodium barbitone +0·075 per cent, glycine at 37°C. for 2-3 hours.

3. In this way thin paraffin sections free from preformed phosphate are obtained.

4. Phosphatase is demonstrated by the Gomori-Takamatsu (1939) technique.

5. Long bones, ribs, and membrane bone from the skull of adult rats and mice and of new-born kittens were examined.

6. Phosphatase was found to be present in the endosteum, the inner layer of the periosteum, the Haversian canals and linings of vascular and marrow spaces, the nuclei of bone marrow and connective tissue-cells, and in isolated osteocytes. The hypertrophic cartilage was positive in both nuclei and matrix in the rodent bones but negative in the kitten bones. The bone matrix and the small-celled cartilage were negative throughout.

7. The possible significance of these findings in relation to the function of alkaline phosphatase is discussed.
Studies upon the Gram Reaction of the Basiphil Cells of the Anterior Pituitary Part II. Observations upon the Effects of Various Methods of Fixation
Authors: Wilson R. R. , Foster C. L.
Published: April 2021

To investigate the effects of fixation on the Gram reaction in the pituitary basiphil granules, frozen sections were made from fixed and unfixed glands, paraffin sections from frozen-dried glands, and paraffin sections in the usual way from whole glands, as well as from several pieces of glands embedded in one block. The fixatives were various well-known mixtures and single substances. Staphylococci were also studied, after treatment with some of the fixatives.

The basiphil granules were always Gram-positive after fixation in formaldehydesaline, formaldehyde-Zenker, Zenker’s fluid, and Zenker stock-solution. Frozen sections of unfixed glands, and sections of frozen-dried glands, were always Gramnegative ; but such sections were usually Gram-positive if left in formaldehyde-saline for at least 12 hours before staining. All other fixatives studied gave negative results. The staphylococci were always Gram-positive.

These findings, and some questions arising from them, are briefly discussed.
The Stomatogastric Nervous System of Arenicola
Authors: Whitear Mary
Published: April 2021

The stomatogastric system of Arenicola marina L. is in the form of a plexus of nerve-bundles connecting the supra-oesophageal ganglia and the circum-oesophageal commissures with a ring ganglion situated in the gut wall at the anterior limit of the oesophagus; the plexus continues down the length of the oesophagus. Numerous sense cells occur in the epithelium of the proboscis and oesophagus. The anatomy of the stomatogastric system is essentially the same in A. ecaudata Johnston and in A. claparedii Levinsen.
Nuclear Transplantation in Amoebae. I. Some species characters of Amoeba proteus and Amoeba discoïdes
Authors: Lorch I. Joan , Danielli J. F.
Published: April 2021

1. The object of this work was to find characteristic differences between stock cultures of A. proteus and A. discoides in order to assess results obtained in experiments involving nuclear transplantation.

2. Previous work on the two species was not found to yield satisfactory diagnostic features.

3. Methods of establishing and maintaining clones and of observing living amoebae are described.

4. As a result of the study of outline drawings of active amoebae and of measurements of the largest diameter of the nuclei, two characters were found which enabled us to distinguish cultures of A. proteus and A. discoides. They were (a) the pattern of locomotion and (b) the distribution of nuclear diameters within a culture.

5. The outlines of active A. discoides tend to be more serrated than those of A. proteus. Outline drawings were readily sorted by independent observers into two categories corresponding fairly closely to the two species. By this method healthy cultures can be identified. Individual amoebae are not always identifiable.

6. An analysis of the longest nuclear diameters of amoebae of the two species showed that the average of a clone and the distribution of nuclear diameters within a clone are typical for each species and are little affected by the age and state of nutrition of the culture. The average nuclear diameter in our cultures, which was found to be independent of the nuclear size of the parent amoeba, was 45 p (s. d. 5-6) for A. proteus and 38-2 p (s.d. 3-6) for A. discoides.

7. The possibility is discussed of using physiological and serological, rather than morphological properties to distinguish between the species.
The Orientation of the Optic Axis of Spicules of Leucosolenia complicata
Authors: Jones Walter Clifford
Published: April 2021

The orientation of the optic axes of the spicules of Leucosolenia complicata has been studied by using isolated spicules and longitudinal sections of the oscular tubes. For tri- and quadri-radiates the mean angle of inclination of the optic axis to the tube wall varies with the distance of the spicule from the oscular edge, particularly over the first 200 μ The spicule form likewise varies with position, but is not closely correlated with the orientation of the optic axis : two spicules can have the same optic angle but different shapes, or the same shape and yet different optic angles. For curved monaxons the optic axis is directed almost at right angles to the spicule axis at the distal end, and the spicule curvature is independent of the position in the tube. Slender monaxons, on the other hand, have an optic axis coincident with the spicule length. It seems a general rule, at least for spicules of L. complicata and L. coriacea, that the optic axis of the first formed calcite rudiment lies in the direction of the cell division (or cell association) that directly precedes spicule formation.

A mechanism is suggested for the orientation of the optic axis. This is explained in terms of an oriented overgrowth of the calcite upon an organic precursor, which is structurally fixed and oriented within the formative cell complex. The arrangement of this complex, by mechanical factors arising during the development of the oscular tube, results in the orientation of the optic axis of the developing spicule. The hypothesis is in accordance with the observations of Minchin on spicule formation.
Note on the Histochemical Localization of Glycogen and Pentosepolynucleotides in the Visual Cells of the Chick (Gallus gallus)
Authors: Rabinovitch M. , Mota Ivan , Yoneda S.
Published: April 2021

Glycogen was studied in retinas of the chick (Gallus gallus), fixed in Gendre’s fluid and stained by the periodic acid/Schiff method. In agreement with some of the earlier data on the subject, obtained with less suitable methods, glycogen was found in the paraboloid of accessory cones and in the characteristically shaped paraboloid of the rods. Basiphilia, observable by means of the gallocyanin-chromalum stain and removable by ribonuclease or perchloric acid, was found in the inner segment of both chief and accessory cones, with the exception of the ellipsoid region.
A Study of the Embryonic development of the Gooseberry Sawfly, Pteronidea ribesii
Authors: Shafiq Saiyid Ahmad
Published: April 2021

The following points in the descriptive embryology of the sawfly appear to be important especially for comparison with the higher Hymenoptera, e.g. the honey bee.

The earlier stages of development (formation of the blastoderm, germinal layers, &c.) take relatively more time in the honey bee than in the sawfly, while the later stages of development (organogenesis) take more time in the sawfly. Only two well-defined germ layers are formed—the outer (ectoderm) and the inner (mesoderm). Cells proliferate from the mid-ventral area of the germ band and spread out to form the inner layer in the sawfly, whereas in the honey bee it forms as a middle plate. Localized proliferations at the anterior and the posterior end of the germ band form two cell-clumps; from these differentiate the midgut epithelium, mesoderm of the procephalic region of the head, muscle layer of the proctodaeum and stomodaeum, and also the germ cells. These are here called the mesendoderm rudiments. The coelom sacs are not well defined from each other but form a more or less continuous tube as in the honey bee. Nucleoli appear in the cells and the cytoplasm becomes basiphil immediately after the formation of the inner layer. Changes in the basiphilia of cells during development are described. The proctodaeum first appears as an invagination in the upturned (dorsal) part of the germ band, which is all used up in its formation, and the edges of the ventral germ band rise up to complete the dorsal closure. The Malpighian tubules develop from the blind end of the proctodaeum and are regarded here as ectodermal; in the honey bee they develop before the proctodaeum is formed. In the advanced embryo the midgut cells have big vacuoles in them and throw out pseudopodia into the lumen of the gut, and the cells of the salivary gland acquire large lobed nuclei. Agreement is expressed with Snodgrass’s view (1938) that the head is composed of four segments and a procephalic region. The labrum has a paired origin (in the honey bee it is unpaired in origin); and as in the honey bee the premandibular segment is not developed. The rest of the body is composed of three thoracic and ten abdominal segments. Paired appendages appear on the thoracic and the second to seventh and tenth abdominal segments (in the honey bee abdominal appendages are not formed). The germ cells arise from the posterior mesendodermal rudiment. In the honey bee they appear to be derived from the genital ridges. There are no blastokinetic movements as in the honey bee. The serosa persists till the hatching of the embryo and secretes a cuticle at an early age. The amnion is not well developed and is transitory; in the honey bee only one embryonic envelope forms.
A Histochemical Study of Fat Absorption in the Small Intestine of the Rat
Authors: Hewitt W.
Published: April 2021

Experiments are described in which sections from the small intestine of rats, fed on triolein hours previously, were examined with Sudan black and the acid haematein test, with and without Sudan red coloration.

The histochemical appearances in the epithelial cells of the mucous membrane are described. Lipoid can be observed not only within the epithelial cells and their free border but also as particles between the cells.
Properties of the Minerals in the Exuvia of Crustacea
Authors: Needham A. E.
Published: April 2021

An unusual reaction between material in the exuviae of Crustacea and pure cold mercuric chloride, resulting in the deposition of a bright red compound, led to the discovery that, contrary to expectation, the inner surface of the fresh moult, and even of the inter-moult exoskeleton, is strongly alkaline (pH = 9·1). This is near the optimum for both alkaline phosphatase and carbonic anhydratase, which both may be active in resorption of mineral preparatory to ecdysis. Correlations between the distributions of the red Hg-compound, phosphate, carbonate, alkaline phosphatase, and pigmentary pattern have been found in various Crustacea. The reaction with cold HgCl2 is given also by the millipede exoskeleton, the molluscan shell, the calciferous gland-material of earthworms (pH 9·2–9·4) and by calcareous sponges, but not by echinoderm or vertebrate skeletons, and not by the exoskeleton of insects, spiders, and centipedes, which lack mineral. The compound(s) with mercuric chloride are probably chiefly oxychlorides. A steady, if slight, solution of the skeletal carbonate and phosphate is necessary to maintain the observed high pH, and to permit the formation of these mercury-compounds.
An Investigation of the Innervation of the Thymus Gland of the Common Mouse, Mus musculus
Authors: Rankin J. J.
Published: April 2021

The anatomical relations of the thymus gland in mice have been studied in serial sections throughout the entire thoracic and posterior cervical regions. No evidence was obtained that the thymus has a secretory function under the control of the nervous system, and no nerve fibres or endings were observed in the proximity of the thymocytes, Hassall’s corpuscles, or reticular cells. The thymic innervation resembles that of the lymph nodes rather than that of the adrenal gland or of the spleen and the neuro-histological picture was unchanged during accidental or age involutions. The thymic innervation consists entirely of autonomic vasomotor nerves originating in an outlying sympathetic plexus—the ‘thymic plexus’, and it is suggested that thymus functions are controlled by vasodilatator and vasoconstrictor mechanisms with the possible aid of thymotropic hormones carried in by the blood-stream. The thymus may aid in the regulation of the lymphocyte content of the blood, acting as a lymphocytic reservoir instead of as a lymphocytopoietic organ.

The source of thymic innervation could not be determined solely by anatomical methods and the majority of current histological techniques were found to be unsuitable for differentiating between nervous and non-nervous argyrophilic fibres. The basic techniques of Holmes and Romanes appeared to satisfy the necessary criteria and Steedman’s ester wax method was successfully used in conjunction with these techniques.
The Structure of the Corpus Cardiacum of Locusta migratoria
Authors: Nayar K. K.
Published: April 2021

The corpus cardiacum of Locusta consists of a syncytium containing nuclei of two sizes. The most obvious cytoplasmic inclusions are spheroid bodies, mostly about 0·6 μ in diameter, which are easily seen in the living tissue, especially by phase-contrast microscopy. They do not appear in routine microscopical preparations, but are blackened by the classical ‘Golgi’ techniques. They give positive reactions for phos- pholipines. The cytoplasm also contains very numerous minute granules, which appear to be mitochondria.
A General-Purpose Method of Silver Staining
Authors: Peters A.
Published: April 2021

A method of silver staining for paraffin sections has been described. Sections should be fixed in either Nonidez fixative, 4% formaldehyde, or 4% formaldehyde saturated with mercuric chloride. The sections are impregnated for 16 hours in 1/20,000 silver nitrate at pH 8 or 9 and developed in a glycine physical developer after the reducible silver has been removed with a 2% solution of sodium sulphite.

The effect of pH on impregnation has been described. A spectrum of staining was obtained in which nerve fibres began to stain appreciably at pH 7, cell nuclei at pH 8, cell cytoplasm at pH 9, and connective tissue at higher pH values. Therefore, impregnation should be carried out at pH 8 to obtain a good staining of nerve fibres and at pH 9 if some staining of cell bodies is also required.
Studies of the impregnation of nervous tissue elements: II. the nature of the compounds responsible for the impregnation of axons; practical considerations
Authors: Wolman M.
Published: April 2021

Axoplasm and axolemma differ in their chemical and physical characteristics. The impregnation of axons is mainly due to a compound which is soluble in hot organic solvents and which appears to be situated in the axoplasm.

Ethylenic linkages and hydroxyl groups play no role in the impregnation of axons. Sulphydryl and carbonyl groups appear to be partly responsible. These groups are situated mainly in the axoplasm, although sulphydryls are present also in the axolemma. The impregnation of axolemma depends to a great extent on chemical groups which could not be identified.

The fact that solutions of Ag diammine are more suitable for impregnating axons than those of AgNO3 might be due to one of the following factors : (1) that the reducing groups of the axons are more easily oxidized at high pH levels; (a) that the complex diammine ion might exert a higher oxidizing activity when reacting with some tissue molecules; (3) that the rate of reaction of the reducing groups of the tissue with the Ag diammine ion might be faster than that with the silver ion.

The Bielschowsky procedure may be carried out successfully on sections of tissue embedded either in paraffin wax or carbowax. With the former procedure care should be taken to minimize contact with mixtures of hot solvents. A further intensification of impregnation of paraffin sections is obtained by treating sections for 24 hours in 4% formaldehyde prior to the Bielschowsky procedure.
An easily made tissue culture perfusion chamber
Authors: Dick D. A. T.
Published: April 2021

A perfusion chamber is described with which a tissue culture can be irrigated successively with different immersion media. Only 1–2 ml. of medium are required for each change, which can be accomplished within 1 minute. Simplicity of design permits speed and economy in manufacture. Perfusion by suction instead of by positive pressure has eliminated certain drawbacks of previous designs. Mixing effects in the chamber have been studied. Any component of an immersion medium can be reduced to 0·5% of its initial concentration by the use of only 2 c.c. of fresh medium. The chamber has been used in the techniques of immersion refractometry and interferometry of living cells.
Amoeba taylorae n.sp.
Authors: Hayes Catherine
Published: April 2021

In material collected from Tannoch Loch, Dunbartonshire, a large free-living, hitherto undescribed amoeba was found. Individual specimens vary in length from 420 to 500μ and in width from 70 to 140μ. Viewed over a black background this amoeba looks dense, white, and opaque, while in transmitted light it has a dusky, almost black, hue, due to the presence in the endoplasm of a large number of small crystals uniform in size, slender and pointed at both ends. There is always a uroid at the hinder end surrounded by bits of debris. The one large nucleus is without a karyosome but has masses of chromatin scattered through the nuclear substance. As a rule there is only one large contractile vacuole, but occasionally a few small ones may be seen at the hinder end. A certain number of nutritive spheres are always present. The author considers this amoeba to be a new species and names it Amoeba taylorae.
The Distribution of Hatching within the Cyst of the Potato Root Eelworm, Heterodera rostochiensis
Authors: Onions T. G.
Published: April 2021

A serial-sectioning technique is described for cysts of the potato root eelworm. The distribution of hatching among eggs contained in the cysts is investigated by this technique. It is shown that there are significant differences in the numbers of larvae emerging from different parts of the cyst, i.e. hatching is not random. There is a tendency for eggs near the cyst wall to hatch sooner than eggs nearer the centre of the egg mass. The position of eggs in relation to the natural openings of the cyst, at the neck and vulva, is apparently without influence on the distribution of hatching. Although the cyst wall is permeable to the hatching stimulant it is argued that the hatching pattern is more likely to be due to a gradient of oxygen tension within the cyst.
The Posterior Lobes of the Brain of Nephtys and the Mucus-Glands of the Prostomium
Authors: Clark R. B.
Published: April 2021

A pair of lobes is attached to the posterior margin of the supra-oesophageal ganglion of some species of Nephtys. They are filled with large, vacuolated mucus-cells similar in appearance and histochemical properties to those found in the anterior part of the prostomium, in the lateral walls of it, and in the parapodia. The mucus-cells of the posterior lobes, and sometimes those of the anterior prostomial group also, have long necks which run in a tract to the epidermis, where they open to the exterior. When this is so, they replace the epidermal mucus-cells found in the lateral walls of the prostomium in species lacking posterior lobes. It is suggested that there has been a centripetal migration of epidermal mucus-cells into the posterior lobes and to the anterior prostomial group, a phenomenon closely paralleling that found in the evolution of the nermertean cerebral organ. In one species, Nephtys cirrosa, the posterior lobe cells appear to have undergone a further modification, for they are much more closely integrated with the nervous system and differ in appearance from those of other species, coming to look, at least superficially, like the majority of neurosecretory cells in the brain.
Histochemical Methods for Protein-bound Sulphydryl and Disulphide Groups
Authors: Gomori G.
Published: April 2021

Histochemical methods for the localization of protein-bound sulphydryl groups were compared in a critical fashion. As far as localization is concerned, several of the methods published were found to be satisfactory. However, from the point of view of approximate visual quantitation, the results are confusing. The two best methods for the histochemical detection of protein-bound sulphydryl groups are the tetrazolium method and Barrnett and Seligman’s dihydroxydinaphthyldisulphide technique.