bluuebunny/crossref_metadata_2025 huggingface dataset:
The Cytology of Amoeba proteus ‘Y’ and the effects of large and small Centrifugal Forces
Authors: Singh B. N.
Published: April 2021

When Amoebaproteusis subjected to high centrifugal force most of the cytoplasmic bodies are thrown out of the cell, so this work was done with the ordinary electrical centrifuge. The stratification of the various cytoplasmic components according to their specific gravity is as follows: the contractile vacuole and the fat, being the lightest, occupy the centripetal position; then there is a layer of cytoplasm followed by mitochondria, neutral-red bodies, crystals, and nutritive spheres. The nucleus occupies a position in between the crystals and the nutritive spheres (Text-fig. 2). The redistribution of the various cytoplasmic components takes place within a few minutes after amoebae have been centrifuged by the electrical centrifuge. Ultra-centrifuged organisms kept in culture solution remain rounded for 10-15 days, and no cyst formation takes place. The crystals and nutritive spheres are reformed; the former seem to be the products of excretion formed by the metabolic activity of the cell. The nutritive spheres contain glycogen as reserve food material, and give positive tests for glycogen with iodine and Best’s carmine. There is no evidence that the bodies which stain with neutral red are the homologue of the metazoan Golgi apparatus, although they are pre-existing bodies in Amoeba proteus. The contractile vacuole does not blacken even after prolonged osmication. No certain homologue of the Golgi apparatus was found in Amoeba proteus. Fat and glycogen are two distinct types of storage material present in Amoeba proteus. The former is very well seen with osmic acid, Sudan IV, and Nile blue tests.
A Study of the Mitochondria of Trypanosomes
Authors: Wotton Robert M.
Published: April 2021

Early observers noted the presence of grannies of indeterminate character in the cytoplasm of certain species of trypano-somes (Franca, 1907 : Policard, 1910). Efforts to establish the nature of these granules by the use of vital stains were not especially fruitful, although the general opinion was held from the beginning that they were not degeneration products of the cell. Shipley (1916), after a careful and thorough study of these cytoplasmic elements in one species of trypanosome, Trypanosoma lewisi, supravitally stained with J anus green, and with fixed preparations, concluded that they were mitochondria. Although their nature is still somewhat uncertain, it seems best to accept this hypothesis. In the present paper the results of the study of several species of trypanosomes are reported with respect to the possible presence of mitochondria. Some of the species of parasites have come directly from experimental vertebrate hosts, one has come from the arthropod vector, and another from culture. Since the mitochondria of the cells of higher species of animals have been associated with certain metabolic functions, the possibility of a relationship between the mitochondria of trypanosomes and trypanosome physiology has been kept in mind while the present study was being carried on.
The Reproductive System and associated organs of the Brittle-star Ophiothrix fragilis.
Authors: Smith J. E.
Published: April 2021

The organs associated, either directly or indirectly, with reproduction in the Ophiuroidea are the axial organ and related sinuses (axial organ complex), the genital rachis, the gonads (localized expansions of the rachis), the gonoducts, and the genital bursae. Evidence is presented in favour of the view of Fedotov (1924) that the axial organ of Ophiuroids is made up of two closely associated parts each surrounded by its own sinus from the wall of which it is, during development, proliferated. The left axial sinus (aboral in the adult) is derived from the left anterior coelom of the larva, the right axial sinus (oral in the adult) from the madreporie vesicle which itself is a derivative of the right anterior coelom of the larva. The ampulla of the stone canal is continuous with, and is part of, the left axial sinus. An account is given of the morphology and histology of the genital rachis and sinus. Examination of the gonads of female Ophiothrix indicate that the breeding season extends from about March to October and that, during this time, there is periodic emission of ova, probably at monthly intervals. Males, on the other hand, produce sperm all the year round. The genital bursae number two pairs to each interradial pouch. They serve, primarily, as organs of respiration. Special mechanisms, which are described, are concerned in the intake and expulsion of water. The gonads do not discharge their products directly into the genital bursae nor through temporarily formed pores in the body-wall but through specially developed and permanent gonoducts, one to each of the ten gonads. Young specimens found in the genital bursae have attained their position only after a period of free-swimming larval life. After settling and metamorphosing, some of the young individuals crawl into the bursae. As a consequence of the previous observation it is pointed out that the presence of the young within the genital bursae of the adult is by no means an indication of a viviparous habit.
The Fate of Spermatozoa in the Female Dogfish (Scylliorhynus canicula)
Authors: Metten H.
Published: April 2021

1. References are given to the literature concerning the fate, in various vertebrates, of spermatozoa in the female genital tract.

2. In the dogfish, penetration of the oviducal wall by spermatozoa does occur. It is confined to the ‘uterus’ and about five millimetres of the oviduct anterior to it. The latter suffers a denser invasion than the ‘uterus’. No spermatozoa invade the cloacal epithelium.

3. Epithelial vacuoles are found in the ‘uterus’, where they may or may not contain spermatozoa, and in the cloaca, where they do not. Any of the vacuoles may contain red and white blood corpuscles.

4. Vacuoles containing blood corpuscles account for a continuous ‘uterine’ bleeding on a small scale.

5. Desquamation of the ‘uterine’ epithelium is slow and continuous, that of the cloacal epithelium intermittent and heavy. Desquamation is not related to the time of copulation.

6. Digestion of spermatozoa and blood corpuscles within the vacuoles may be very incomplete.

7. The spermatozoa which enter the columnar epithelium near the ‘uterus’, frequently pass right through and into the superficial connective tissue. No vacuoles are produced in the columnar epithelium. Presumably all such spermatozoa are phagocytosed.

8. No fusion occurs between the heads of the spermatozoa and thé nuclei of any of the cells of the oviducal wall, as described by Kohlbrugge.

9. The proportion of spermatozoa destroyed in the lower oviduct is not sufficient to prevent them ascending the upper oviduct in large numbers.

10. A theory is advanced to account for the facts concerning the destruction of spermatozoa in the oviduct.
Some Histochemical Observations on Amino-acids and Nucleic Acids in the Wool Follicle
Authors: Ryder M. L.
Published: April 2021

A study of staining at different pH values showed that the fibre became decreasingly basiphil at successively higher levels. This was supported by an increased reaction for basic groups after keratinization, although a reaction for acid groups was obtained in the normally basiphil pre-keratinization region, and the keratinized fibre after vigorous treatment.

The reactions for individual amino-acid residues are probably not quantitative, but indicate availability to react. The strongest reaction for arginine was in the tricho- hyalin of the medulla and inner sheath, for tyrosine and tryptophan in the keratinized part of the fibre, and for histidine in both the keratinized and unkeratinized parts.

Most reactions gave asymmetrical results, but vigorous treatment tended to produce uniform results. This supports the suggestion that the asymmetry is due to differences in accessibility rather than to chemical differences.
An Electron Microscope Study of a Small Free-living Amoeba (Hartmanella astronyxis)
Authors: Deutsch K. , Swann M. M.
Published: April 2021

The fine structure of a species of small free-living amoeba, Hartmanella astronyxis, has been investigated. The mitochondria resemble those of other species of amoeba. Structureless bodies of about the same size as mitochondria are sometimes found in association with them. Double membranes are common in the cytoplasm, and may show granules along their outer borders. The nuclear membrane is a double-layered structure, with a honeycomb structure evident in tangential sections. The cell membrane is also double-layered, or occasionally multi-layered.
A Quantitative Study of the Cytoplasm of Ascites Tumour Cells in Mice
Authors: King R. J.
Published: April 2021

This paper describes how a combination of microspectroscopy and interference microscopy has been used to investigate the composition of the cytoplasm of fresh ascites tumour cells of mice. The accuracy of the microspectroscopic method will be very dependent on the standard absorption curves used (i.e. results obtained from dilute nucleic acid and protein solutions of known concentration), and particular attention has therefore been given to this aspect of the investigation. Thus, the standard protein absorption curve has been derived in two ways, first from a certain assumed amino-acid composition, and secondly by a method involving the optical density and refractive index of the ascitic fluid itself. Both methods are shown to result in similar cellular analyses.

The cytoplasm of the ascites cell can be divided broadly into two regions—a granular zone of comparatively low ultra-violet absorption, and a peripheral region possessing greater absorption, but with little structure visible by the optical microscope. Absorption measurements at 257 and 275 mμ show that, despite the difference in ribonucleic acid content in these two regions, the protein concentrations are approximately the same.

For comparison with these microspectroscopic results, optical retardations have been measured in the identical regions of the same ascites cells. Total dry mass concentrations, evaluated interferometrically, were found to be in good agreement with the sum of the nucleic acid and protein weights, these being obtained from the ultraviolet results. This indicates that the ultra-violet absorption of the cytoplasm of the fresh ascites cell is not grossly different from that to be expected from its extracted nucleic acid and protein components. It is stressed that the material used in this investigation was in many ways suitable for quantitative absorption measurements and equally consistent results should not be expected from all other types of cells, particularly those measured after fixation rather than in a fresh condition.
Observations upon the Nervous Systems of Pelagic Tunicates
Authors: Bone Quentin
Published: April 2021

The sensory and motor systems of the pelagic tunicates Doliolum, Salpa, and Thalia are described, chiefly from observations made upon the living animals by phase-contrast microscopy. These observations confirm and extend previous work, showing that the sensory systems of these animals are anatomically highly specialized. Details of the sensory cells are shown from living specimens. It is shown that the motor systems of Doliolum and the salps are essentially similar, but that of Doliolum is less specialized. The condition of the visceral nervous system in these animals is discussed, and it is concluded that the salps possess peripheral nerve-cells upon the viscera; illustrations are given of these cells from fixed specimens.
The Use of the Philips ‘Mirror-condenser Lamp’in Microscopy
Authors: Baker John R. , Llowarch Wilfrid
Published: April 2021

The primary source of light is a coiled filament. Ellipsoidal and spherical mirrors collect nearly all the light it produces and project it on to an area of about mm outside the bulb. One end of a solid glass rod is placed in or near this area. The light travels along the rod by internal reflexions. A bull’s-eye lens, placed beyond the other end of the glass rod, focuses the emerging light on the lower focal plane of the substage condenser of the microscope. Very intense illumination is produced. It is moderated by a variable resistor.

The lamp is suitable for use with objectives of focal lengths from 16 mm downwards. It is particularly adapted to high-power microscopy of all sorts. It is easy to use.
Sections of Fresh Mammalian Nerve-trunks for Quantitative Studies: A Rapid Freezing Technique
Authors: Williams P. L.
Published: April 2021

Attempts to assess the effects of shrinkage and distortion inherent in the conventional histological procedures used during quantitative analysis of nerve structure have hitherto proved unsatisfactory. The evolution of a technique in which such effects are minimized is therefore desirable.

A segment of fresh nerve, implanted in a mass of supporting tissue (fresh liver), is frozen by a solid CO2/acetone mixture, and sectioning is subsequently performed in a cryostat. The sections are flattened on pre-cooled slides, irrigated with saline, and photographed.

Regular, stable serial sections, 3 to 5 μ in thickness, may be produced. Such sections show typical internodal annuli of compact myelin, shearing defects of Schmidt-Lanterman type, and paranodal crenations of the myelin sheath. Occasional defects of preparation include rupture of isolated fibres, herniation of myelin, and the appearance of myelin spheres.

When studies involving precise measurement are contemplated, the use of orthodox transmitted illumination, dark-ground illumination, and phase contrast is precluded by diffraction effects and the occurrence of reverse-contrast haloes at the tissue interfaces. Polarizing microscopy has proved satisfactory.

It has been shown that estimates of the relative size of the axon and myelin sheath, obtained from sections prepared in this manner, do not differ significantly from the relative sizes measured in fibres freshly teased in physiological saline (Wendell-Smith and Williams, 1959).
The Association of a Slime Bacterium with the Inner Envelope of the Egg of Dytiscus marginalis (Coleóptera), and the less common Occurrence of a similar Bacterium on the Egg of D. semisulcatus
Authors: Jackson Dorothy J.
Published: April 2021

The egg of Dytiscus marginalis L. is laid under water in the mesophyll of the leaf of various aquatic plants. The egg increases in size during development and this results in the splitting of the chorion, the outer envelope of the egg, usually into two halves. The inner envelope of the egg, the vitelline membrane, then forms the only complete shell of the egg in its later stages.

During the development of the embryo of D. marginalis the cysts of a slime bacterium (myxobacteriale) appear in great numbers on the vitelline membrane along the dorsal surface of the embryo and around each end of the egg. They are at first small and scattered, but by the time the larva hatches they are present in dense colonies.

These bacterial cysts occur on eggs collected from water plants in ponds; but they develop just as readily on eggs obtained in the laboratory by placing the female D. marginalis in jars of tap-water with leaves that have never before been immersed in water.

Slime bacteria in the vegetative stage are carried in great numbers by the female D. marginalis, as has been shown by trailing the apex of the abdomen of a living beetle over an agar culture, when swarms of the characteristic rod-like cells have been obtained. Some of these bacteria will be transferred from the beetle to the egg during oviposition.

The bacterial cysts do not occur on unhealthy eggs and they rarely show normal development on eggs parasitized by the mymarid, Caraphractus cinctus Walker. This suggests that their development is dependent upon the healthy growth of the Dytiscus embryo.

In the egg of D. semisulcatus Mull, the chorion remains in close contact with the vitelline membrane throughout embryonic development and only occasionally shows small irregular cracks before hatching. On some eggs of this species a few scattered cysts of slime bacteria occur on the vitelline membrane. On occasional eggs they were more numerous, but they were never observed to be present in sufficient numbers to form the even covering which is so striking a feature of certain parts of the egg of D. marginalis.
Some Observations on the Cytology of the Adenohypophysis of the Non-parous Female Rabbit
Authors: Allanson M. , Foster C. L. , Menzies G.
Published: April 2021

Evidence is presented which suggests that in this animal the pars tuberalis may have some function in addition to acting as a bed for the hypophysial portal system, since its cells appear rich in RNA.

The granules of the cells of the pars intermedia are shown to be PAS-positive, but this reaction, unlike that of the basiphil cells of the pars distalis proper and the zona tuberalis, is readily prevented by pretreatment of sections with proteolytic enzymes.

A study of the basiphil cells of the pars distalis proper and of the zona tuberalis, based on cytological characteristics, size, and shape, provides some evidence for the existence of two, and possibly three, kinds of basiphil cell.

The lipid inclusions of the adenohypophysial cells and their relationship to the Golgi elements are described, together with some brief preliminary observations upon the electron microscopic characteristics of acidophil and basiphil cells.
The Possible Calcification Mechanisms in some Reptilian Egg-shells
Authors: SIMKISS K. , TYLER C.
Published: April 2021

Studies have been made of the organic matrix of certain reptilian egg-shells. The interaction between egg-shell-matrix and various metal ions has been considered by noting the effect of these ions on the staining of the matrix by toluidine blue. A comparison of the results with those for the hen indicates that the chelating mechanism in the Chelonia is similar to that in the hen, but that that in the Crocodilia is different. It is suggested that in the Crocodilia the acid mucopolysaccharide of the matrix is embedded in, but not combined with, the protein and that its chelating mechanism is carboxylate group to carboxylate group, while in the hen and Chelonia, the acid mucopolysaccharide is combined with the protein and that its chelating mechanism is carboxylate group to amino group.
Further Observations on the Development of the Peptic Cells of the Rabbit’s Stomach
Authors: Menzies Gordon
Published: April 2021

I. The loss of the mucinogen component of the peptic granules begins during the fourth week of post-natal life (400 g) at a site on or near the greater curvature of the stomach adjacent to the pyloric antrum. It reaches the lesser curvature at about the sixth week (750 g).

2. The loss progresses slowly across the ventral and dorsal walls of the stomach and more rapidly along the greater curvature.

3. At 11-12 weeks (1,800 g) only a few peptic cells on the greater curvature and adjacent to the oesophageal opening contain PAS-positive granules.

4. Except for a few granules in an occasional peptic cell, no mucinogen can be demonstrated in these cells after the fourteenth week (1,900 g).

5. The stage seems to be correlated more closely with the weight than with the age of the animals.
An Anatomical, Histological, and Histochemical Study of the Gut of the Brachiopod, Crania anomala
Authors: Chuang S. H.
Published: April 2021

The anatomy of the gut in Crania anomala Müller was described by Joubin (1886) and Blochmann (1892), both of whom also made some observations on its histology. The present paper gives an account of the structure of the gut and the results of some histochemical tests.
The Fine Structure and Histochemistry of the Ligaments of Nephtys
Authors: Clark M. E. , Clark R. B.
Published: April 2021

A unique ligamentary system occurs in the polychaete Nephtys. Its fine structure and physico-chemical properties have been investigated.

The ligaments consist of alternating bands of elastic and inelastic elements, and they attach to the body by means of crystalloid attachment nodes. The nodes are probably glycoprotein in nature as they contain both protein and polysaccharide. They are not birefringent, and they are insoluble in comparison with the other components of the ligaments. Their structural stability is due mainly to strong ionic and hydrogen bonding. They resist enzymatic digestion.

The inelastic elements are bundles of thin, birefringent fibrils, 10 to 14 μ in length. The birefringence is positive with respect to the long axis of the fibrils and is primarily intrinsic in nature. The estimated coefficient of birefringence has a value between 10 and 20 × 10-3. The fibrils consist of a protein with an isoelectric point near pH 6 · 3. The visible structure of the fibrils is due to both hydrogen and ionic bonding, while the birefringence is more dependent on hydrogen bonding. The fibrils resist heating and peptic digestion, but are slowly digested by trypsin. Of all the fibrous proteins, they most resemble collagen.

The elastic elements are extremely fine, granular cross-membranes bearing delicate filaments to which the ends of the fibrils are attached. They are continuous with a bounding membrane surrounding the ligament, which also bears granules and is also elastic. Some of the granules appear to be folds of the membrane itself. The membranes consist of a protein which is quickly digested by trypsin but not digested by pepsin. Its isoelectric point lies near pH 5. Hydrogen bonding is more important than ionic bonding in the membranes, and Van der Waals forces may also contribute. Classification of this protein is not yet possible.
Cyclical Changes in the Distribution of the Testis Lipids of a Seasonal Mammal (Talpa europaea)
Authors: Lofts B.
Published: April 2021

In the mole, Talpa europaea, there occurs a sequence of interstitial events comparable with that of seasonal birds, reptiles, and some fishes. There is a periodic accumulation and discharge of cholesterol and lipids in the Leydig cytoplasm. This cycle differs from its avian counterpart in that whereas in birds (and some fishes) the Leydig cells rapidly discharge their sudanophil contents before mating, the interstitium of the mole becomes exhausted much more slowly. Another difference is that the Leydig cells of the mole do not appear to become exhausted and replaced en masse as in birds after spermatogenesis. The seasonal growth and regression of the mammalian accessory sexual organs can be correlated with the increase and decrease of secretory activity of the interstitial cells (as shown by their lipid cycle). In the seminiferous tubules of the mole there is no lipid cycle corresponding to that observed in sub-mammalian vertebrates.
The Total Solids in the A- and I-Band Regions of Living Mammalian Striated Muscle-fibres
Authors: Ross K. F. A. , Casselman W. G. B.
Published: April 2021

Living muscle-fibres from freshly killed mice were mounted in isotonic saline /protein media and examined with a Smith interference microscope, usually with a white light-source. When the A or I bands near the edge of a fibre were observed to match the colour of the background field, their refractive indices were close to that of the mounting medium; although it is extremely probable that diffraction at the edges of the adjacent unmatched bands affected their apparent match, so that they were not exactly of this refractive index. Matched A bands were distinguished from matched I bands by examining them in plane-polarized light, by rotating the preparation through a right angle under the interference microscope to display their birefringence, and from the colour of the unmatched bands when the fringe system of the microscope was left unaltered.

In any one fibre, the refractive indices of the 71-band regions were always higher than that of the Z-band regions. The H bands had lower refractive indices than the A bands, and the Z bands higher than the I bands, but these were both too narrow to be matched satisfactorily by this method. The refractive indices of the solutions in which matched I bands were found ranged from 1·358 to 1·363, and those in which matched A bands were found from 1·360 to 1·366. The mean refractive index of the A and I bands was very close to 1·363, which is equivalent to a total solid content of 16% w/v.

These findings are in good general agreement with those of H. Huxley and Hanson (1957) and Bennett (1955), who measured the distribution of solid material in isolated glycerinated mammalian myofibrils; but the difference between the refractive indices of the A- and Z-band regions of the living fibres appeared to be very much less. Only part of this discrepancy can be accounted for by the presence of non-fibrillar solid material, because the total amount of this is extremely unlikely to exceed 50% of the total myofibrillar fibrous protein. It therefore seems probable that, because of the diffraction from the unmatched bands, the true refractive indices of the A bands were higher than those of the solutions in which they appeared matched, and those of the Z bands were correspondingly lower than those of the solutions in which they appeared matched.

The maximum error involved here (when the sarcomere interval was approximately 2·5 μ) can be quantified from independent estimations of the non-fibrillar material in whole muscle (Szent-Gyôrgyi and others, 1955; Hanson and H. Huxley, 1957); and from this it seems highly probable that the refractive indices of the I bands were not lower than 1·350 (equivalent to a solid content of 9% w/v), and those of the A bands were not higher than 1·375 (equivalent to a solid content of 23% w/v).
The Chromosome Numbers and Nuclear Cytology of some Common British Serpulids
Authors: Dasgupta S. , Austin A. P.
Published: April 2021

The chromosome numbers of Hydroides norvegica, Mercierella enigmática, and Pomatoceros triqueter were determined from squashes of somatic cells in young embryos obtained by artificial fertilization, and stained with iron-alum/aceto-carmine. All had a diploid count of 2n = 26 chromosomes. Mitotic and meiotic divisions in the 5 species of Spirorbis examined, and in Filograna implexa, all revealed a diploid chromosome number of 2n= 20. A diploid chromosome number of 14 is suggested for the ancestral serpulid.
On the Interpretation of Phase-contrast Images
Authors: Steel W. H. , Tchan Y. T.
Published: April 2021

It is shown that the simple theory of phase-contrast microscopy may be extended to take some account of the size of the object by the introduction of an ‘overlap factor’ which expresses the fraction of the diffracted light that passes through the phase-changing region of the phase plate. The extended theory can explain observed effects that cannot be explained even qualitatively if overlap is ignored. The overlap factor is given for disk-shaped objects and an annular phase plate.
The Fine Structure of Epithelium and Mesogloea in a Sea Anemone
Authors: Batham E. J.
Published: April 2021

Ultra-thin sections of mesenteries of a sea anemone provisionally referred to Metridium canum have been examined in the electron microscope. The flagella show the common 9:2 fibrous structure, the peripheral fibres fusing basally and appearing to run through continuously to basal corpuscle and banded rootlet. Arising from the epithelial surface, as well as flagella, are numerous palisade processes, some radiating from flagella bases. These extensive processes show internal fibrous structure. Mesogloeal fibres show strong banding, with a period of about 42 to 46 mμ.
A Note on the Habits and Nutrition of Solemya parkinsoni (Protobranchia: Bivalvia)
Authors: Owen G.
Published: April 2021

Adult specimens of Solemya parkinsoni Smith, embedded in mud at a depth of 50 cm or more, were collected near low water (spring tide). The animal burrows with the anterior end downwards and does not maintain an opening to the surface. An inhalant current is drawn into the mantle cavity anteriorly on each side of the foot, while an exhalant current leaves by the single, posteriorly situated aperture. This is probably a respiratory current, bottom material entering the mantle cavity as a result of the muscular activity of the mantle and foot.

The course of the alimentary canal is described, and the problem of feeding and nutrition correlated with the extreme reduction of the gut exhibited by S. parkinsoni discussed. It is suggested that an initial breakdown of organic material may take place in the mantle cavity.
On the Filamentous Elements in the Nucleoli of Chick Embryo Fibroblasts
Authors: Guttes Edmund , Guttes Sophie
Published: April 2021

Filamentous inclusions (= nucleolonemata) in the nucleoli of chick embryo fibroblasts and their behaviour during the cellular cycle are described. Their number is about the same as that of the macrochromosomes. They originate in anaphase as thin threads along the chromosomes. During the reconstitution of the daughter nuclei they aggregate within two nucleoli. They disintegrate with the prophase of the next mitosis.
Morphological and Histochemical Studies of the Chromatoid Body in the Grass-snake, Natrix natrix
Authors: Sud Bhupinder N.
Published: April 2021

The chromatoid body in the spermatogenesis of the grass-snake, Natrix natrix, has been studied by the use of phase-contrast microscopy, vital dyes, and histochemical tests.

It first appears during the growth of the primary spermatocyte and is also seen in the secondary spermatocyte and late spermatid, but is absent at metaphases of both the maturation divisions, in the early spermatid, and during the final stages of spermateleosis. It does not make any visible contribution to the final make-up of the spermatozoon.

In living cells it gives a very low phase change, and is not stained by neutral red or Janus green. The histochemical study reveals that it consists mainly of RNA and of proteins with abundant acidic and basic groups.

It is tentatively suggested that its function is to provide basic proteins for the final maturation of the chromatin in the nucleus of late spermatid.
Structure and Movements of Tick Spermatozoa (Arachnida, Acari)
Authors: Rothschild Lord
Published: April 2021

1. The spermatozoa of the tick, Ornithodoros moubata, which until now have been reported to move without any apparent means of propulsion, have been examined under the light and electron microscopes.

2. The surface of the spermatozoon is covered with ridges, running parallel to the long axis of the body, 0· 30 to 0·47 μ long and 500 to 1,000 A wide.

3. In longitudinal section approximately every other ridge exhibits wave-like deformations.

4. On the basis of these sub-microscopic structures and the behaviour of polystyrene balls stuck to the surface of live spermatozoa, the hypothesis is put forward that tick spermatozoa move by propagating lateral bending waves along the ridges in an antero-posterior direction.

5. No ‘9 + 2’ or ‘9 + 9 + 2’ arrangement of fibrils has been observed anywhere in tick spermatozoa.

6. There is a striking though not complete resemblance between the sub-microscopic surface structure of tick spermatozoa and that of gregarines.
The Coelomic and Peritoneal Cell Systems of some Sabellid Polychaetes
Authors: Phillips Dales R.
Published: April 2021

The growth and activity of the coelomic cells of Sabella spallanzanii are described. Qualitative and quantitative determinations were made throughout the year of the glycogen, oil, and pigments which they contain. The coelomic cells accumulate carotenoids, including astaxanthin. The possibility of the interconversion of glycogen and oil by the cells is discussed, and it is concluded that the coelomic cells constitute a depot for the maturation of the gametes. This system is paralleled in some other sabellids by the development of a villous peritoneum. Such tissues contrast with the chloragogen tissue in that they have no direct contact with the blood vascular system.
Morphological and Histochemical Studies of the Chromatoid Body and Related Elements in the Spermatogenesis of the Rat
Authors: Sud Bhupinder N.
Published: April 2021

In the spermatogenesis of the rat the chromatoid body is present during the growth of the primary and secondary spermatocytes, disappears at telophase of both the meiotic divisions, and is absent during interkinesis. It is reconstructed during the early stages of spermateleosis but after the elongation and condensation of the nucleus it gradually becomes smaller and disappears. Simultaneously, in the caudal region von Ebner ‘s stainable granules appear and gradually fuse together to form a single voluminous body, Regaud ‘s sphère chromatophile, which is discarded with the residual body and is phagocytosed by the Sertoli cell.

The histochemical studies reveal that the chromatoid body, von Ebner ‘s stainable granules, and the sphère chromatophile are similar in composition. They consist mainly of RNA and proteins, and this suggests that they may be centres of protein synthesis. The RNA content of von Ebner ‘s stainable granules and the sphère chromatophile appears to be higher than that of the chromatoid body. This probably means that there is a progressive decrease in the protein component of the chromatoid material. Also there is a distinct change in the chemical composition of the protein component of the chromatin during the late stages of spermateleosis. It is tentatively suggested that the function of the chromatoid material may be to provide basic proteins for the final maturation of the chromatin of the late spermatid.

It appears that the chromatoid elements originate from the ground cytoplasm and disappear by merging into the latter.

An enigmatic granular satellite has been found associated with the chromatoid body. It differs from the latter in its chemical composition.
The action of ribonuclease on the nucleic acid system of Spirostomum ambiguutn
Authors: Dass C. M. S. , Vimala Devi R.
Published: April 2021

The experiments described in this paper have shown that the enzyme ribonuclease (RNase) is able to enter Spirostomum ambiguum. There is a definite concentration/time relationship in the action of RNase on the ribonucleic acid (RNA) system of the organism. The rate of action of the enzyme is proportional to its concentration in the medium. At high concentration the enzyme causes instant degeneration of the cell. At lower concentrations the enzyme acts specifically on RNA present in the cytoplasm and in the macronucleus; it causes complete loss of basiphilia. Loss of basiphilia occurs first in the cytoplasm and later in the macronucleus.

The organisms after treatment with the enzyme, when transferred back to enzymefree Chalkley’s medium, regenerate RNA. The RNA appears first in the macronucleus and later in the cytoplasm.
Histochemical demonstration of certain DPN-linked dehydrogenases and of aldolase in the red and white fibres of pigeon breast-muscle
Authors: George J. C. , Talesara C. L.
Published: April 2021

The distribution and localization-pattern of certain DPN-linked dehydrogenases (malic, lactic, D-glucose, glutamic, and a-glycerophosphate) were demonstrated histochemically in the red and white fibres of pigeon breast-muscle by using neotetrazolium as the hydrogen acceptor, under strictly anaerobic conditions. All the dehydrogenases studied showed distinctly higher enzyme activity in the narrow red fibres than in the broad white fibres. That of a-glycerophosphate was, however, found to be appreciably more abundant than other dehydrogenases in the broad fibres. A high concentration of aldolase, which forms an important link in the chain of enzymes in glycolysis, was histochemically demonstrated in the broad, white, glycogen-loaded fibres.
Neurosecretory control of ovarian development in Schistocerca gregaria
Authors: Highnam K. C.
Published: April 2021

Cautery of the neurosecretory cells of the pars intercerebralis, or removal of the corpora cardiaca, will prevent the development of the terminal oocytes in the ovaries of the desert locust. Implantation of brains into females whose neurosecretory cells have been cauterized results in some development of the terminal oocytes. Ovariectomy of immature females causes a precocious accumulation of material in the neurosecretory system. Electrical stimulation, drastic wounding, or enforced activity of 14-day-old females reared without males brings about release of material from the neurosecretory system, and also accelerates development of the terminal oocytes. Copulation by these females also results in release of material from the neurosecretory system, and is followed by rapid terminal oocyte development. It is concluded that the neurosecretory system in Schistocerca gregaria exerts a positive control over oocyte development, and that copulation may stimulate release of material from the neurosecretory system.
Histological changes in the gut and associated tissues of Mitopus morio (Phalangiida) during digestion of lipid and carbohydrate
Authors: Phillipson John
Published: April 2021

In Mitopus morio both lipid and glycogen are stored in the connective tissues. The lipid stores reach their maximum at approximately 48 h after feeding, whereas glycogen reaches a maximum at 12 h and then gradually disappears only to reach a second maximum at 48 h. This second maximum is probably due to the conversion of lipid and/or protein into glycogen. Glycogen formed the main storage material (on a volume basis), a result which differs from that of Kastner (1935) and Frank (1937), who regarded lipid as the main storage product. The survival periods of starved adults of M. morio are 6·4 ± 0·8 days (males) and 8·6 ± 0·6 days (females).
Breakdown and formation of connective tissue in the pupal stage of an insect
Authors: Whitten Joan M.
Published: April 2021

Changes occurring in the connective-tissue elements in the pupae of some Diptera Cyclorrhapha are described. The larva and the adult are characterized by an organically continuous system of investing membranes. The pupa is, on the whole, characterized by the absence of investing membranes. Early in the pupa most of the larval membranes are destroyed. In some cases the associated cells also disappear; in others the cells remain. Disappearance is not simultaneous throughout an organ; usually the anterior most segments of the organ disappear first. The adult membranes are formed in the late pupa, after the processes of growth, cell-division, and differentiation are completed. Fusion of membranes would appear to result from co-ordinated secretion, and be a delicately timed process. It is suggested that the larval membranes are similarly produced in the embryo, at the end of differentiation and organ formation, and that in the case of both larva and adult, the invested cells are concerned with the secretion of, and the destruction of, the investing membranes.
A study of the fixation of the granular elements in rat pancreas
Authors: Levene C. , Feng P.
Published: April 2021

Rat pancreases were fixed in 6 primary fixatives and 16 fixative mixtures. Paraffin sections were stained for a and zymogen granules with chromalum/haematoxylin/phloxine, and for β granules with aldehyde-fuchsin.

Fixation of α. And β granules was obtained with all fixatives containing formaldehyde or potassium dichromate. Zymogen granules were only fixed by fixatives containing formaldehyde, and then only if acetic acid was omitted.

Formaldehyde alone was adequate for fixation of a, α, and β zymogen granules. For fixation of a and (β granules only, the mixture of formaldehyde and acetic acid was preferable because the sections were technically better.
Variations in histology of abdominal stretch receptors of saturniid moths during development
Authors: Finlayson L. H. , Mowat D. J.
Published: April 2021

In the stretch receptors of Lepidoptera there are normally two giant nuclei, but supernumerary giant nuclei are frequently present. In a study on Sarnia cynthia supernumerary giant nuclei have been found to occur most frequently in the first, second, third, and fourth abdominal segments. They are present in the larva, pupa, and adult. Small nuclei in the muscular component of the receptors are infrequent in the larva and in the fourth, fifth, and sixth abdominal segments of the adult; but in the first, second, and third abdominal segments there is an increase in small nuclei at metamorphosis. Small nuclei also multiply in the receptors of the eighth and ninth segments but these receptors degenerate. The muscular component of the receptors that metamorphose at first becomes reduced and loses its striations and then differentiates anew. In those receptors that disappear (eighth and ninth) dedifferentiation is succeeded by histolysis. A third category of nucleus, larger than the small nuclei but smaller than the giant nuclei, was found in a few receptors of larva, pupa, and adult. Such nuclei appear to be absent from the fifth and sixth segments, but they were too rare for reliable statistics to be obtained.
Phosphatases in the neurones of Locusta migratoria
Authors: Lee Rosemary S.
Published: April 2021

Frozen sections of motor neurones in the thoracic ganglia of Locusta migratoria were treated for thiamine pyrophosphatase activity and for acid phosphatase activity. The TPPase-positive bodies range from 0·5 to 1·25 μ. diameter and appear to be the small, membrane-bound inclusions described by Ashhurst and Chapman (1962) in their electron-microscope work; these are the smaller lipochondria of Shafiq (1953). The acid-phosphatase-positive bodies range from 1 to 2·5 μ diameter and seem to be the lamellar aggregates described by Ashhurst and Chapman that are very similar to γ-cytomembranes, and which are the larger lipochondria of Shafiq. It is concluded that the enzyme content of the γ-cytomembranes is very different in this cell from their content in the vertebrate neurone, and doubt is thrown on the usefulness of TPPase activity as a marker for the Golgi apparatus in invertebrate tissue.
An adrenergic nervous system in sea anemones
Authors: Dahl Erik , Falck Bengt , Mecklenburg Claes Von , Myhrberg Harry
Published: April 2021

A new method for the demonstration of certain mono-amines by means of fluores- cence microscopy was applied to the tentacles and oral disk of the sea anemones Metridium senile and Tealia felina.

A fluorescent substance was found in the cells and fibres of the tentacular ecto- dermal nervous system.

This nervous system probably has a double sensory and motor function.
Localization of enzymes in certain secretory cells of Helix tentacles
Authors: Lane Nancy J.
Published: April 2021

Secretory cells in the optic tentacles of the snails, Helix aspersa and H. pomatia, have been investigated for the cytoplasmic localization of certain enzymes. The collar cells, considered to be neurosecretory, and the lateral oval cells, were those examined. Acid phosphatase activity is found in the cytoplasm of both cells, in scattered spheroids called the β-bodies. This enzymatic activity indicates that the β-bodies may be lysosomes, as does their ultrastructural appearance. In the 2 cell types, the activity of both alkaline phosphatase and thiamine pyrophosphatase is localized in crescentic bodies considered to correspond to the Golgi lamellae, and in some of the β-bodies. The latter enzyme also exists in the cortices of the a-bodies which, like the β-bodies, are lipid-containing globules. The activity of both cytochrome oxidase and succinate dehydrogenase is found, not only in granules, rods, and filaments interpreted as the mitochondria, but also on the cortices of some or all of the β-bodies. It is concluded that in invertebrates, the lipochondria may be the sites of activity of many different enzymes which in vertebrates are restricted to distinct cell organelles.
Electron microscopy of the ovary of Fasciola hepática
Authors: Gresson R. A. R.
Published: April 2021

The external wall of the ovary of Fasciola hepática is a membrane-like structure in contact with a non-cellular material in the ovary. An intercellular region containing an amorphous material of moderate electron density is present in the ovary. The primary oocytes are provided with peripheral processes that extend into the intercellular region. The oocytes do not proceed beyond the prophase of the first meiotic division until after they leave the ovary. The nucleolus of the primary oocyte contains vacuole-like areas and emits granular material to the nucleoplasm; some of this material may move to the cytoplasm. Pores are present in the nuclear envelope. In older oocytes narrow bridge-like structures connect the nucleolus and the nuclear envelope. The nuclear envelope of the primary oocyte undergoes replication. It is continuous with the endoplasmic reticulum and the plasma membrane. The location of the mitochondria is correlated with the phases of growth of oogonia and oocytes. The mitochondria possess irregularly arranged cristae. Small, round or oval nutritive bodies are present in the peripheral cytoplasm of older oocytes. It is suggested that areas of relatively high density containing vacuole-like structures represent the Golgi complex.
The effect of certain fixatives on particles of a globular protein: an electron-microscopical study
Authors: Deutsch K. , Fischer E. , Krause W.
Published: April 2021

Particles (regarded as molecules) of bovine serum albumin have been studied by electron microscopy both in the untreated state and after fixation with osmium tetroxide, formaldehyde, and potassium permanganate. All three fixatives, especially potassium permanganate, increased the density of the particles considerably.
The giant mitochondria of ctenophore comb-plates
Authors: Horridge G. A.
Published: April 2021

The elongated cells which bear the continually active giant cilia of the combs contain numerous large mitochondria, up to 8 μ by 6 μ in size, which are filled with irregular tubular cristae. The ciliated cells are up to too p long, but only io p wide, and from their centrally situated nucleus can be traced a succession of stages, tentatively interpreted as the formation, growth, erosion, and final dissolution of mitochondria. Small ones occur near the nucleus in the region of the nuclear membrane, which may there be irregular, puffy, and electron dense. Some small mitochondria are surrounded by amorphous material which stains heavily with lead ; others lie against the nuclear membrane, as if in intimate relation with it. Cristae of mitochondria which are interpreted as juvenile are filled with an amorphous material ; some of the cristae open to the outside of the mitochondrion. Towards the ciliated end of the cells the appearance of the mitochondria suggests that they are breaking down; this is the region where food particles are eroded and where the cilia consume energy. Here the mitochondria are shrunken and around them are numerous vesicles ; their cristae are fewer and they open into the cytoplasm. Similar vesicles, which are apparently of mitochondrial origin, are extruded between the cilia from the cells. The proposed cycle of generation and disintegration of mitochondria, based upon morphology, is so far an unproved hypothesis.
The double-impregnation silver technique for nerve fibres in paraffin sections
Authors: Fitzgerald M. J. T.
Published: April 2021

Fixation and staining sequences are given for the impregnation of mammalian neurones, in paraffin sections, with silver nitrate followed by protargol. The end- results resemble those obtained by optimum use of the Bodian technique.