bluuebunny/crossref_metadata_2025 huggingface dataset:
Ester Wax as a Medium for Embedding Tissue for the Histological Demonstration of Glycogen
Authors: Smyth J. D. , Hopkins C. A.
Published: April 2021

The effect of paraffin wax embedding on the lability of glycogen in sections has been tested using as material (a) plerocercoid larvae of Ligula intestinalis’, (b) rabbit liver. It was found that glycogen in tissues was very impermeable to wax, and where large masses of glycogen occur prolonged embedding is essential. Improperly embedded material lost glycogen easily; it was concluded that this loss takes place during the processes of cutting and flattening sections. The effect of prolonged embedding was to make tissue hard and refractive. This difficulty was overcome by embedding in Steedman’s ester wax. Ester wax blocks allowed thin sections of very hard material to be cut with ease. Ester wax sections brought down to water did not lose glycogen even after standing in water for 7 days. It is emphasized that glycogen exists in two forms: an insoluble desmo-form and a soluble lyo-form. It is suggested that the latter does not dissolve from sections in water because its highly branched molecule is held by the coagulated protein network.
A New Single-control Micromanipulator
Authors: Barer Robert , Saunders-Singer A. E.
Published: April 2021

New developments in microscopy and electrophysiology have brought a renewal of interest in methods of micromanipulation.

A number of features desirable in the design of a micromanipulator is discussed.

A new micromanipulator is described. Its outstanding features are (1) single control; (2) massive construction with freedom from vibration; (3) freedom from play; (4) continuous variability of sensitivity; (5) limitation of range of movement to the field of view; (6) rapid low-power centring; (7) unusual robustness combined with delicacy of movement achieved without any high-precision methods. The performance of the instrument is adequate for high-power cytological work and for microdissection by phase-contrast illumination.
Further Remarks on the Golgi Element
Authors: Baker John R.
Published: April 2021

The Golgi element has been reinvestigated in the same kinds of cells as were the subject of the author’s 1944 paper. Two new methods have been used, namely, phase-contrast microscopy and an improved form of the sudan black technique, in which the tissues are postchromed at 60° C. The Golgi element consists of separate bodies, spheroid in shape. These Golgi bodies may be simple (i.e. non-vacuolate), or may contain one or more vacuoles. The material of the simple Golgi body and of the externum of the vacuolate body is a lipoid that in some cases can be shown to contain lipine. The secretion-product of the Golgi body originates in the vacuole. The opinion as to the structural plan of the Golgi element set out in the earlier paper has been confirmed in the main. There are, however, two exceptions to this: The vacuole in the Golgi body does not invariably colour with neutral red, and this dye occasionally causes the appearance of vacuoles not present before, both within the Golgi region and in other parts of the cytoplasm. ‘Diffuse lipoid’ is not a characteristic feature of the Golgi element.
Aldehydes in relation to Absorption of Fat from the Intestine and Metabolism of Fat in the Liver
Authors: Danielli J. F.
Published: April 2021

During the absorption of fatty acids or of fat from the intestine of mice and rats, no intervention of long-chain aldehydes occurs. When fat is being metabolized or synthesized in the liver of mice and rats aldehydes are prominent. Each fat droplet being metabolized is sur- rounded by a spherical shell containing aldehyde and basiphilic material. The results indicate that long-chain aldehydes or their derivatives are essential intermediates in the metabolism of fatty acids, and suggest that the acetals of these aldehydes are intermediates in the synthesis of glycerides and phospholipines, &c.
The Histochemical Detection of Beryllium
Authors: Denz F. A.
Published: April 2021

During an investigation of the toxic action of beryllium salts on experimental animals a histochemical test was developed to provide information on the distribution and site of action of beryllium. The technique is reported as an example of the application of chemical methods to histological problems.
A Simple Method for Phase-contrast Microscopy: Improvements in Technique
Authors: Baker John R. , Kempson D. A. , Brunet P. C. J.
Published: April 2021

If the condenser of a microscope is first set in its so-called ‘critical’ position and then gradually lowered, the real image of the source sf light will be brought down from the plane of the diaphragm of the eyepiece till it reaches a position just behind (above) the back focal plane of the objective. If a piece of black paper, from which a ring-shaped strip has been cut away, is held immediately in front of the source of light, a bright image of the annulus can easily be thrown just behind the back focal plane of the objective by lowering the condenser to the appropriate degree. If now a phase-plate, provided with an annulus, is placed in the same plane as the image of the illuminating annulus, and if the phase-plate annulus is of such dimensions that it coincides with this image, phase-contrast microscopy will have been achieved.
The Cell-Theory: a Restatement, History, and Critique Addendum to Part II
Authors: Baker John R.
Published: April 2021

Since writing Part II of this series of papers (Baker, 1949), I have had the good fortune to find a figure, published by Roffredi in 1775, which shows nuclei in the eggs and embryos of a nematode. This figure antedates by fifty-five years Purkinje’s description of the germinal vesicle (1830) (or by fifty years, if we use the date of the private circulation of Purkinje’s memoir).
Mitosis in the Mouse : A Study of Living and Fixed Cells in Tissue Cultures
Authors: Fell Honor B. , Hughes A. F.
Published: April 2021

1. Mitosis has been investigated in cultures of infant mouse tissues, in both living and fixed material.

2. Phase microscopy combined with serial photography was used to study the living cell.

3. The formation of chromosomes has been traced in the living cell from the intermitotic chromonemata and heterochromatic chromocentres.

4. Dividing cells can be recognized early in prophase and the duration of each phase of mitosis has been measured.

5. Curves of anaphase movement have been plotted; they are sigmoid as in amphibian cells.

6. The reconstruction of the daughter nuclei has been studied in detail in both living and fixed cultures. The chromosomes swell, then begin to lose their nucleic acid charge and to unravel into a web of fine threads. The nucleolar material can be identified in the living cell early in telophase; it appears as a diffuse system of lumps and strands occupying most of the nucleus and its direct transformation into the interphase nucleoli was followed in the film records.

7. The origin of polyploid nuclei by the mitosis of binucleate cells has been demonstrated.

8. Analysis of the film records showed that the average length of the intermitotic period is 12 hours.
A Simple Method of Staining the Basement Membrane of Glomerular Capillaries
Authors: Linder J. E.
Published: April 2021

In 1943 Thomas described a haematoxylin phosphomolybdic acid lake which stained collagen and reticulin. This observation has been confirmed and extended by the chance observation that on long stan’ding the lake acquires the power of colouring the basement membrane of the glomerular capillaries.
The Influence of a Gonadotrophin on the Seasonal Changes in the Testis and Deferent Duct of the Chaffinch (Fringilla coelebs)
Authors: Sluiter J. W. , Van Oordt G. J.
Published: April 2021

1. Male chaffinches (Fringilla coelebs) were treated with gestyl, a gonadotrophin prepared from pregnant mare serum, in different seasons; using different techniques their testes and deferent ducts were histologically studied after autopsy on u August, 30 November, 28 January, and 5 May.

2. After Champy-fixation and Altmann-staining two types of interstitial cells can be distinguished in the intertubular tissue of sexually active chaffinches : lipoid cells, (= Leydig cells) and secretion cells.

3. Results of gestyl-administration : In summer- and winter-birds (Pl. I) whose testes are in the resting stage, the testis-tubule diameter shows a strong enlargement, which is partly due to the plasma of the cells being distinctly inflated ; spermatogenesis does not take place. In the intertubular tissue lipoid and secretion cells appear in abnormally large numbers. In 10 days the deferent ducts pass over from the quiescent into the fully-activated stage. In spring-birds (Pl. Ill), being in the reproductive stage, the administration of gestyl has practically no effect. In this stage the intertubular tissue also contains both lipoid and secretion cells.

4. From the results mentioned under 3, and the fact that in the control bird of 28 January, being in the beginning of the progressive stage (Pl. II), many lipoid cells were found, whereas its deferent ducts were still quiescent, it is concluded that only the secretion cells produce the male sex-hormone. The lipoid cells, which amongst others contain cholesterol, possess only a trophic function.

5. The difference in reaction of the seminiferous tubules of birds to chorionic and hypophyseal gonadotrophins as well as the function of the interstitial cells are discussed. Most opinions on the last-mentioned subject are not sufficiently well founded, as the investigators used routine techniques only for the cytological investigation of the interstitial tissue.
The Structure of Whale Blubber, and a Discussion of its Thermal Properties
Authors: Parry D. A.
Published: April 2021

As a warm-blooded animal, a whale must be adapted not only to prevent an excessive loss of heat but also to control the rate of heat loss in relation to changes in its metabolic activity and in the temperature of its surroundings. This paper contains an account of whale blubber considered from this point of view. The first part is devoted to the morphology of blubber, particular attention being paid to the blood circulation which does not appear to have been previously described; and the second part contains a discussion of the efficacy of blubber as a thermal insulator of controllable conductance. The results are based on a study of the Common Porpoise (Phocaena phocaena), and the Blue and Fin Whales (Balaenoptera musculus and B. physalus).
Heliospora n.g. and Rotundula n.g., Gregarines of Gammarus pulex
Authors: Goodrich Helen Pixell
Published: April 2021

From this study of the unknown stages in the life-histories of the two polycystid gregarines, which have been known for just 100 years in Gammanes pulex L., it is concluded that the long thread-like one should be Heliospora longissima (Siebold) and the short rounded one Rotundula gammari (Diesing), and that some other Amphipods have the same or similar gregarines.
A Critical Study of Techniques for the Cytochemical Demonstration of Aldehydes
Authors: F. Danielli J.
Published: April 2021

A critical study has been made of Feulgen’s technique for demonstrating tissue aldehydes. Conditions are given within which the technique is reliable on the cytological scale. Five supplementary tests for aldehydes are described. It is shown how distinction may be made between free aldehyde, acetal aldehyde, and aldehyde formed by oxidation.
The Digestive Mechanism of the European Squids Loligo vulgaris, Loligo forbesii, Alloteuthis media, and Alloteuthis subulata
Authors: Bidder Anna M.
Published: April 2021

1. The digestive mechanism has been investigated in Loligo forbesii, L. vulgaris, Alloteuthis media, and A. subulata. Histology and morphology were examined on living and fixed material and the feeding of L. vulgaris was observed in the living animal.

2. The food is bitten by the jaws and rapidly swallowed; the radula has no rasping action.

3. Preliminary digestion takes place in the stomach, which is cuticle-lined.

4. The caecum is a complex organ, containing the opening of the mid-gut gland. This opening is connected with the closing mechanism of the caeco-intestinal opening in such a way that the hepato-pancreatic secretion can be directed either to the caecum or to the stomach. The anterior part of the caecum contains a ciliary collecting mechanism whose main groove leads along the intestine towards the anus.

5. The posterior part of the caecum is a simple ciliated sac where digestion is completed, food absorbed, and pancreatic secretion stored between meals. Solid food other than particulate is never found in the caecum.

6. The intestine is a short, straight tube, lined with a ciliated and mucous epithelium. Absorption also takes place here, and continues after the caecum has ceased absorbing.

7. The junction of intestine and rectum is considered to be defined by the replacement of the ciliated epithelium by one with a hyaline border.

8. The rectum is short; in the region of the rectal sphincter it is lined with cells bearing curious retractile processes, whose possible function is discussed.

9. The mid-gut gland secretes all digestive enzymes; it is divided into two unequal and markedly different glands: the so-called ‘fiver’ and ‘pancreas’. These are connected in series, so that hepatic secretion flows through the main lumen of the pancreas to reach the caecum.

10. Hepatic secretion is passed into the caecum only during digestion. The liver has a single type of cell in which food reserves also accumulate. The hepatic duct can be closed by a sphincter.

11. Pancreatic secretion accumulates in the caecum between meals and apparently passes to the stomach during digestion. The structure and rhythm of the cells of the pancreas and the nature of its blood-supply suggest some second activity, possibly directed towards the blood-stream, alternating with that of enzyme-secretion.

12. Food is not absorbed in the mid-gut gland.

13. The structural and functional peculiarities of the digestive system of these squids may be related to an exceptionally speedy and efficient digestive mechanism, well fitted to the life of a perpetually swimming, active predator.
Low-power Phase-contrast Microscopy without a Condenser
Authors: Kempson D. A.
Published: April 2021

With those low-power objectives in which a phase-plate can be placed near the back focal plane, phase-contrast microscopy can be obtained without the use of any condenser. The illuminating annulus is placed in the conjugate focus of the phaseplate.
The Physiology of the Alimentary Canal of Tyroglyphus farinae
Authors: Hughes T. E.
Published: April 2021

1. The pH of the stomach and its caeca lies between 5·0 and 6·0, that of the colon changes to the alkaline side of 7·0 but remains below 8 0. The pH of the post-colon is between 7·0 and 8·0. All these measurements are subject to protein error.

2. The stomach and its caeca are regions of:

(a) absorption;

(b) secretion of a mucus containing a digestive enzyme;

(c) digestion of carbohydrate and protein

3. The optimum pH of carbohydrate digestion is 5-4 and of protein digestion 5·6±2.

4. The thin-walled colon regulates the pH of the food bolus and is the site of formation of a peritrophic membrane and some absorption.

5. The post-colon is the site of further absorption of water and solidification of the faecal pellet.

6. Excretory substances are first recognizable in the colon; they do not appear to be produced by the Malpighian tubules or post-colon.

7. The chief nitrogen katabolite is guanine.

8. There is an accumulation of nitrogenous katabolites in the parenchyma of the body in animals on a high-protein diet.

9. The powers of excretion of nitrogenous waste appear to be poor.

10. The main food reserves are of glycogen in the parenchyma; fat is not stored to any extent.

11. The salivary glands produce a mucus which serves as a lubricant for the food in its passage through the pharynx and oesophagus.
The Outer Layers of the Cuticle in the Cockroach Periplaneta americana and the Function of the Oenocytes
Authors: Kramer S. , Wigglesworth V. B.
Published: April 2021

In the epicuticle of the cockroach there is a cement layer formed, as in other insects, by secretion from certain of the dermal glands at the time of moulting. These dermal glands are widely distributed over the abdominal tergites and sternites in both sexes. Their cell-bodies are atrophied in the mature insect. They differ in this respect from the very numerous dermal glands on the abdominal tergites of the male, which remain distended with vacuoles.

The cuticular wax, which is freely exposed on the surface of the cuticle, is thought to be produced by the sub-epidermal oenocytes and to be discharged during the life of the cockroach, perhaps through the pore canals, by the epidermal cells.

The oenocytes of the honey-bee are much larger during the height of wax secretion than they are in the foraging bee.

The view that the oenocytes are concerned in wax metabolism is compatible with the view that they synthesize the lipoprotein (or wax protein) components of the cuticle and egg-shell.
A Study of the Male Germ-cells of the Rat and the Mouse by Phase-contrast Microscopy
Authors: Gresson R. A. R.
Published: April 2021

1. The cytoplasmic components of the male germ-cells of the rat and the mouse were examined by phase-contrast microscopy. Most of the structures seen in fixed and stained preparations were identified.

2. The localized Golgi material of spermatocytes and spermatids consists of rods and filaments. The mitochondria are granular.

3. The archoplasmic vacuole, proacrosome, developing acrosome, proximal and distal centrioles, and the axial filament were visible. A structure which may be an accessory body was observed in spermatocytes and spermatids. The manchette was visible in late spermatids of the rat but not in those of the mouse.

4. Examination of spermatozoa revealed the acrosome, the post-nuclear cap, the mitochondrial sheath, the ring centriole, and the protoplasmic bead. A granule was sometimes visible in the neck region.
Cytochemical Studies on the Embryonic Development of Drosophila melanogaster: II. Alkaline and Acid Phosphatases
Authors: Yao T.
Published: April 2021

1. Drosophila ovary and testis are very rich in acid phosphatase, but contain no histochemical trace of alkaline phosphatase. Thus the mature oocyte shows a strong acid phosphatase reaction both in the nucleus and cytoplasm. Sperm heads are equally reactive.

2. Acid phosphatase is demonstrable in Drosophila embryos from early cleavage up to the hatched larva. No striking change in enzyme activity has been observed during this period.

3. Alkaline phosphatase is not detectable in the first half of embryonic life. It suddenly appears in the ventral ectoderm near the future thorax during or shortly after the contraction of the germ band. The enzyme activity then spreads to the other parts of the embryo following definite patterns, until finally the whole embryo becomes active. The possible mechanism of the spreading of enzyme activity is discussed.

4. Alkaline phosphatase disappears in most tissues before hatching, but is retained in the gut epithelia, salivary glands, and Malpighian tubes. The relationship of this enzyme to histo-differentiaton is suggested.

5. The centte of origin of alkaline phosphatase activity is considered as the ‘differentiation centre’ of the Drosophila embryo.

6. The high cytoplasmic acid phosphatase activity of the oocyte and nurse cells and a similar activity of the yolk in the developing embryos indicate that the enzyme plays some role both in the synthesis and in the degradation of yolk.
Studies of the Egg of Bacillus libanicus (Orthoptera, Phasmidae) : I. The Egg Envelopes
Authors: Moscona A.
Published: April 2021

1. The structure of the eggs of Bacillus libanicus (Uvarov) is described and measurements given. Both structure and size were found to vary considerably

2. The axial orientation of the eggs is not in accord with ‘Hallez’s law’, as the dorsal and ventral sides of the egg and of the early embryo are diametrically opposite to those of the mother.

3. The microscopic structure of the egg envelopes is described. The egg is covered by three main envelopes: a hard, brittle exochorion built of seven distinct layers, two of which consist almost solely of calcium salts; a double-layered, membranous endochorion·, a thin vitelline membrane. Layers of the chorion may be summarized as follows:

(i) exochorion—tubercular layer, dark layer, lamellar membrane, calcium oxalate layer, intermediate lamella, calcium carbonate layer, shell membrane.

(ii) endochorion—outer and inner membrane.

4. In developing eggs the calcium carbonate layer of the exochorion becomes reduced owing to loss of material from its inner surface. Consequently the shell membrane, initially attached to this layer, becomes almost completely detached. The calcium carbonate layer in shells of eggs which do not develop remains unchanged.
On the Cytochemical Demonstration of Aldehydes
Authors: Danielli J. F.
Published: April 2021

Techniques are discussed for the cytochemical demonstration of (a) free aldehydes, (b) aldehyde acetals, and (c) aldehydes formed by oxidation.
Metachromasy of Nucleic Acids
Authors: Lison L. , Mutsaars W.
Published: April 2021

If nucleic acids and a metachromatic dye are mixed in amounts giving a low nucleic acid : dye ratio a ‘positive’ metachromatic effect occurs similar to that observed with truly chromotropic substances: for instance, thionine or toluidine blue become red or reddish-violet. This may be observed in test-tubes with pure solutions of the substances. In microscopical preparations this occurs when the staining, is strong.

If the amount of N.A. is such that the ratio N.A. : dye is high, a ‘negative’ metachromasy occurs, that is, shades of colour are produced that are greener than those obtained in pure water solutions. In microscopical preparations this occurs when the staining of nuclei is very light.

Both ‘positive’ and ‘negative’ metachromasy have the characteristics of truly metachromatic phenomena—specific absorption curves and suppression by heat.
An Investigation of the Histochemical Technique for the Localization of Acid Phosphomonoesterase
Authors: Macdonald Frances
Published: April 2021

A method is described for assessing the depth of ‘staining’ obtained with the acid phosphatase technique and a detailed scheme is given of the standard technique used. It is concluded that the technique specifically demonstrates the activity of acid phosphatase, since ‘staining’ is abolished in the absence of substrate, in heated sections, and in the presence of fluoride. An investigation has been carried out to determine the extent to which the reaction is affected by altering various stages in the technique. The effect of formalin fixation on the reaction has been investigated. It has been shown that sites in the rabbit medulla having an affinity for the reagents used in the technique differ from the sites at which a precipitate is deposited as a result of enzyme activity. Evidence is presented suggesting that the technique may not demonstrate the true physiological localization of the enzyme. It is suggested that the technique may be of value as a neurohistological method.
A Review of the Methods available for the Determination of the Types of Forces Stabilizing Structural Proteins in Animals
Authors: Brown C. H.
Published: April 2021

The types of linkages holding protein chains together are discussed, and methods described for determining the types of linkage in animal structural proteins. A short account is given of the results of such tests applied to a variety of invertebrate and vertebrate structures.
On the Use of Wide Illuminating Cones in the Microscope
Authors: Oettlé A. G.
Published: April 2021

In bright-ground illumination, glare is noticeable when the condenser aperture is equivalent to that of the objective. It can still be detected, though to a greatly reduced extent, after most causes of glare have been avoided. It is suggested that this residual glare is inevitable, and represents the loss of contrast resulting from a relative excess of direct rays, which occurs when the direct light falls in the marginal zone of the objective, since half of the diffracted rays then falls outside the lens.
The Mesoglea and Muscle-fibres of Chlorohydra viridissima
Authors: Holmes William
Published: April 2021

The structure and relations of the mesoglea, muscle-fibres, arid cell layers were examined by several histological techniques.

Evidence is given that the muscle-fibres represent specializations of the mesogleal substance, and they are therefore referred to as mesogleal fibres.

The longitudinal fibrous system is regularly demonstrable in the body of the animal and the circular system in its tentacles. The circular system in the body cannot regularly be shown and is variable in its appearance.

The evidence from the study of the fibres, and of the mesoglea of the pedal disk, leads to the suggestion that some at least of the fibres are labile structures, ‘crystallizing’ from the mesoglea according to the shape and movements of the animal.
The Water Relations and Cuticle of Paradesmus gracilis (Diplopoda, Strongylosomidae)
Authors: Cloudsley-Thompson J. L.
Published: April 2021

Water-loss in Paradesmus gracilis depends upon temperature and humidity, and is directly related to saturation deficiency. There is no evidence of any ‘critical point’ to indicate an epicuticular wax layer. Water is readily lost and taken up through the cuticle, the effect of the spiracles and of excretion being negligible. Despite great sensitivity to desiccation, there is nevertheless some degree of impermeability.

The cuticle is in many ways similar to that of an insect: it is composed of a ‘cuticulin’ epicuticle, a ‘tanned’ chitinous exocuticle, and a laminated endocuticle of two optically distinguishable layers. The outer endocuticle is strongly calcified. The cuticle is penetrated by pore canals and the ducts of dermal glands. The latter are concerned with the production of exo- and endocuticle, and the secretion of the polyphenols which tan the protein of the exocuticle. The double hardening is probably a specialized condition of millipedes.

Transpiration is almost quadrupled by extraction with hot, but not cold chloroform, as the exocuticle is impregnated with lipoids which reduce permeability. These are secreted by epidermal and dermal gland cells, and pass up the pore canals and gland ducts.
Aggregata leandri n.sp
Authors: Goodrich Helen Pixell
Published: April 2021

The schizogony of a newly discovered Aggregata from the prawn, Leanaer squilla L., is described, but its sporogony, expected in Octopus vulgaris, could not be found in the one specimen examined.
Sporozoa of Sipunculus
Authors: Goodrich Helen Pixell
Published: April 2021

The gregarines of Sipunculus, so often recorded during the last hundred years, prove to belong to two or more species of the genera Urospora and Lithocystis, and further information especially about the gametes and zygotes is much needed.

The structure of the spores, the most diagnostic feature of gregarines, forces one to recognize three species, viz. Urospora légeri, U. hardyi, and Lithocystis lankesteri, as distinct from the original U. sipunculi Köll.
Alcian Blue 8GS: A New Stain for Mucin
Authors: Steedman H. F.
Published: April 2021

A new method of staining mucin is described. The stain used is alcian blue 8GS The method is rapid and easy in application. The results are clear and permanent.
The Ecology and Digestive System of the Struthiolariidae (Gastropoda)
Authors: Morton J. E.
Published: April 2021

The two neozelanic species Struthiolaria papulosa and Pelicaria vermis have been studied as regards ecology, feeding mechanism, and structure and function of the digestive system. They are dwellers on sand or sand-mud-flat, with a feeding position just below the surface, where they construct paired siphonal tubes with the rostrum. A ciliary mode of feeding has been acquired by the modification of the gill filaments and the pallial rejection system. The alimentary canal is adapted for deposit feeding and has developed a crystalline style. Food particles are conducted to the stomach by a functionally reduced mucus-secreting oesophagus, where they are subjected to the action of the rotating style, and a complex system of ciliary currents. Digestible particles are passed into paired diverticula, where absorption and intracellular digestion. takes place, while faecal material is surrounded with mucus and formed into firm pellets by the ciliary and muscular action of the intestine. The relationships of the Struthiolariidae are discussed, and their origin from the Aporrhaidae is postulated.
Sensory Cells and Pigment Distribution in the Tail of the Ammocoete
Authors: Steven D. M.
Published: April 2021

The ammocoete of Lampetra planeri (Bloch) contains a single carotenoid, lutein, partly esterified and partly in the free state. The pigment is distributed in lipophores in the sub-dermal tissues, and plays no part in the colour changes of the animal.

The epidermis of the tail contains numerous sensory cells of a type previously undescribed, which satisfy the requirements predicted for the photoreceptors responsible for the light reaction of the animal.

Evidence is presented that these sensory cells are innervated by branches of the lateral line nerves.

Similarities are indicated between the sensory cells of the ammocoete and simple photoreceptor systems of certain invertebrates.
The Stolonic Vessels of the Didemnidae
Authors: Millar R. H.
Published: April 2021

Stolonic test vessels are described in four members of the ascidian family Didemnidae. The epidermal cells of the terminal swellings of the vessels appear to produce test substance. The stolonic vessels, area of budding and muscular appendix are probably all derived from the posterior end of the ancestral zooid.
The Blood-system in the Serpulimorpha (Annelida, Polychaeta): III. Histology
Authors: Hanson Jean
Published: April 2021

The histology of the blood-system of Pomatoceros triqueter has been studied in detail. Comparative observations have been made on the following serpulids and sabellids: Serpula vermicularis, Hydroides norvegica, Vermiliopsis infundibulum, Sal- macina incrustans, Protula intestinum, Apomatus ampulliferus, Spirorbis militaris, S. cor- rugatus, Sabella spaUanzanii, Potamilla sp., and Dasychone lucullana. Living coelomic capillaries of Sabella have been investigated. All vessels possess a three-layered wall consisting of an endothelium, a skeletal coat, and a peritoneum containing muscle-fibres which lie transversely to the long axis of the vessel. The outer wall of the gut sinus had the same three layers. On its inner side the sinus is bounded by an endothelium lying on a skeletal coat which in most species is the basement membrane of the gut epithelium. In Sabella and Branchiomma a muscle coat, with fibres lying transversely to the long axis of the gut, is situated inside the inner skeletal coat and rests on the basement membrane of the gut epithelium. The function of these muscles is not known. Longitudinal muscles are found in the same position in Myxicola. The endothelium of the coelomic capillaries of Sabella, and probably of all serpulids and sabellids, is a syncytial reticulum of cell bodies connected by cytoplasmic strands. The endothelium of Sabella and Branchiomma, but not of the other species investigated, contains chloragosome-like globules. In Sabella it also contains iron in some organic compound. Blood-cells are absent from all serpulids and sabellids investigated. The skeletal coat is linked by fibres with the rest of the internal skeleton of the body. It is a homogeneous sheet of a substance giving the staining reactions of collagen. Reticular and elastic fibres are absent from it. When the vessel contracts the skeletal coat does not change in thickness but is thrown into longitudinal folds. The coelomic capillaries of Sabella have a peritoneum which is apparently syncytial, and in which are muscle-fibres arranged in a wide-meshed reticulum. The reticulum and the nuclei of the peritoneum can be vitally stained with methylene blue. The nuclei are sparsely scattered over the surface of the vessel without any special relation to the fibres of the reticulum. On the larger vessels and on the gut sinus separate muscle-fibres, each with one nucleus, are present. The peritoneum constitutes a muscle-epithelium. The nucleus lies in a small membrane of cytoplasm extending along the outer surface of the fibre. The muscle-fibres of the gut sinus are composed of unstriped fibrils. The fibres of the smaller vessels sometimes show alternating stained and unstained bands of equal length. On the larger vessels each muscle-fibre apparently contains both striped and unstriped fibrils. The fibre seems to be covered by a thin sheath of striped fibrils covering a central core of unstriped fibrils which are arranged so that the core shows a double-oblique striation. The muscles of the rest of the body are unstriped.
The Tegumental Glands in the Land Isopoda: B. The Lobed Glands: Structure and Distribution
Authors: Gorvett H.
Published: April 2021

The structure and distribution of the lobed glands in Porcellio scaber Latr. are described. The glands have a remarkable structure, each being deeply divided into many lobes, and provided with four nuclei which do not appear to be separated by cell membranes. They open externally at intervals along the margins of the body, on the lateral plates and uropods, always by separate pores, and always in exposed positions. The lateral plate and uropod glands resemble each other in many respects, but differ in size, staining reactions, and type of secretion. The glands do not differ in the two sexes, and are present in young animals newly liberated from the brood pouch. The glands of Porcellio scaber Latr. are compared with those of one species of each of the following genera: Asellus, Limnoria, Idotea, Ligia, Ligidium, Trichoniscus, Haplophthalmus, Oniscus, Platyarthrus, Hemilepistus, and Armadillidium. Lobed glands are peculiar to the terrestrial Isopoda (Oniscoidea), and appear to be present in all genera of this group, but no related structures are known in other Crustacea. They vary little in essential structure or distribution in the various genera. They vary considerably in size and number, but this variation is independent of sex, moulting condition, evolutionary position, respiratory mechanism, or humidity requirement. The lobed glands appear to have been evolved in adaptation to terrestrial life, but their function does not seem to be connected in any way with the problems of reproduction, moulting, respiration in air, or adaptation to dry surroundings.
A Twin-knife Microtome Attachment
Authors: Sloane J. F. , Harris J. E.
Published: April 2021

A microtome knife carrier, holding two knives, has been designed to produce alternate sections as two separate ribbons. The position of the knives can be altered to give sections of the same or of different thickness in the two ribbons. The application of this device in various histochemical and counting techniques is-briefly indicated.
The Effect of Cortisone on Uterine Growth in Ovariectomized Rats receiving Estradiol
Authors: Fawcett Don W. , Deane Helen Wendler
Published: April 2021

The growth of the uterus in ovariectomized rats treated with estradiol was compared with that of similar animals given both cortisone and estradiol.

Examination of histological sections of the uteri of rats treated in these two ways revealed no significant differences in general histological topography or cytology.

The results of one of the two experiments performed suggested that cortisone may antagonize the increase in interstitial fluid of the uterine wall but does not interfere with the growth of the uterus which results from administration of an estrogen.

These results are compared with those on skin and other organs in which cortisone has been found to inhibit the growth and repair of mesenchymal tissues.
The Role of Iron in Histological Staining
Authors: Wigglesworth V. B.
Published: April 2021

Rapid methods for staining sections with iron sulphide are described which give results comparable with iron haematoxylin.

Nucleic acids and proteins are mainly responsible for the uptake of iron. The staining capacity of different proteins runs parallel with the number of free carboxyl groups they contain. It is concluded that the iron forms non-ionizing complexes with carboxyl and phosphoric acid groups.

The intensity of staining is a measure of the relative abundance of such groups in the proteins and nucleic acids present, and of the concentration density of these substances.

In the staining of nuclei and chromosomes with iron the proteins are at least as important as the nucleic acids.

The iron taken up is mostly in the ferric state but it is partially converted to ferrous iron by reducing substances (chiefly sulphydryl groups) present in many fixed tissues. Iron in the form of iron sulphide or undifferentiated iron haematoxylin therefore acts as a metachromatic stain : a blue colour indicates ferrous iron, a brown colour ferric iron.
Studies of the Histology of the Mid-gut of the Chelonethi or Pseudoscorpiones
Authors: Gilbert Owen
Published: April 2021

The histology of the mid-gut of Dactylochelifer latreilli (Leach) is described. The mid-gut is divided into two regions : an anterior diverticular region consisting of digestive cells, excretory cells, and small basal cells of unknown function, and a narrow, posterior post-diverticular region possessing a syncytial epithelium. The whole mid-gut is invested in a layer of peritoneal cells. The changes in the staining reaction of protein globules undergoing intracellular digestion are followed. The development of excretory cells is described. The function of the post-diverticular mid-gut in the excretory process is outlined. Storage of fatty material and glycogen occurs in the digestive cells and in the peritoneal epithelium. The structure and functions of the false scorpion mid-gut are compared with those of other Arachnids.
Studies upon the Gram Reaction of the Basiphil Cells of the Anterior Pituitary: Part I. Some Preliminary Observations upon the Basiphil Cell of the Human Pituitary
Authors: Foster C. L. , Wilson R. R.
Published: April 2021

The basiphil cell granules of the human anterior pituitary react positively with Gram’s stain, but no specific differentiation of these granules occurs when the iodine treatment is omitted. The granules of the acidophil cells are Gram-negative.

Various workers have suggested a connexion between the Gram reaction of various micro-organisms and the presence of ribonucleoprotein, and the pituitary cells were investigated from this point of view.

Pyronin methyl green staining demonstrates what is probably ribonucleoprotein material in the cytoplasm of both chromophobes and chromophils, but not in the granules of either kind of chromophil. As with micro-organisms, the Gram reaction is destroyed by treating the sections with hot oxygenated bile salt, which has a detergent action upon the ribonucleic acids, but, unlike micro-organisms, the reaction remains unaffected by digestion with a buffered solution of crystalline ribonuclease, although this treatment destroys the nucleic acid, as demonstrated by the loss of pyronin basiphilia in the cytoplasm.

Bile salt also diminishes the strong positive reaction of the basiphil cell granules to the periodic acid Schiff (P.A.S.) test—a reaction which probably indicates the presence of intragranular mucoprotein.

It seems unlikely that the Gram-positive reaction of the basiphil cell granules of the human anterior pituitary is due simply to the presence of ribonucleoprotein.

We have employed the term ribonucleic acid, bearing in mind that this is a generic term and not the name of a single molecular species (cf. Davidson, 1950).
The Cell-theory: A Restatement, History, and Critique: Part III. The Cell as a Morphological Unit
Authors: Baker John R.
Published: April 2021

A long time elapsed after the discovery of cells before they came to be generally regarded as morphological units. As a first step it was necessary to show that the cell-walls of plants were double and that cells could therefore be separated. The earliest advances in this direction were made by Treviranus (1805) and Link (1807).

The idea of a cell was very imperfect, however, so long as attention was concentrated on its wall. The first person who stated clearly that the cell-wall is not a necessary constituent was Leydig (1857). Subsequently the cell came to be regarded as a naked mass of protoplasm with a nucleus, and to this unit the name of protoplast was given. The true nature of the limiting membrane of the protoplast was discovered by Overton (1895).

The plasmodesmata or connective strands that sometimes connect cells were probably first seen by Hartig, in sieve-plates (1837). They are best regarded from the point of view of their functions in particular cases. They do not provide evidence for the view that the whole of a multicellular organism is basically a protoplasmic unit.

Two or more nuclei in a continuous mass of protoplasm appear to have been seen for the first time in 1802, by Bauer. That an organism may consist wholly of a syncytium was discovered in i860, in the Mycetozoa. The syncytial nature of the Siphonales was not revealed until 1879. The existence of syncytia constitutes an exception to the cell-theory. No wholly syncytial plant or animal reaches a high degree of organization.

Natural polyploidy was discovered by Boveri (1887), who was also the first to produce it experimentally (1903). Although many organisms contain some polyploid constituents and others are polyploid throughout their somatic tissues, yet diploid and haploid protoplasts (haplocytes and diplocytes) are the primary components of plants and animals and are still retained as such by most organisms. The haplocyte is more evidently unitary than the diplocyte.

Haplocytes and diplocytes are not composed of lesser homologous units, and with the necessary reservations required by the existence of syncytial and polyploid masses of protoplasm, they may therefore be said to be the fundamental morphological units of organisms.
Some Effects of Abnormal Tonicity on Dividing Cells in Chick Tissue Cultures
Authors: Hughes Arthur
Published: April 2021

Chick tissue cultures were treated with hypo-and hypertonic saline for periods up to i hour. Dividing cells are more sensitive than resting cells to abnormal tonicity. The effects of this treatment on dividing cells closely resembles that of various mitotic inhibitors. Cells are arrested either in pre-prophase or in metaphase, in which the chromatid pairs are scattered throughout the cell. With hypotony, anaphase may be disturbed, and cleavage may be prevented. There is partial recovery when cultures are returned to normal saline after this treatment. Cells re-enter mitosis. After hypotonic saline, inhibited metaphases may either regenerate a spindle, or their scattered chromosomes may reconstruct as irregular nuclei or as separate chromosomal vesicles. These results may have some bearing both on the course of normal mitosis and on the action of mitotic inhibitors.
Further Observations upon the Oxyntic Cells with Special Reference to Acid Phosphatase
Authors: Menzies Gordon
Published: April 2021

In continuation of work already reported (Menzies, 1949) further data are presented on the structure and cyto-chemistry of the granules in the oxyntic cells of the rat’s stomach. After multiple doses of pilocarpine or histamine, and after feeding, the phos-pholipine (as shown by acid haematein) is shed from some or all of the granules. The lipine first leaves the granules in cells situated in the basal part of the tubules, and finally those in the neck of the tubules, but a non-lipine lipoid remains in all the granules (as shown by sudan black). The granules enlarge after prolonged starvation as they do after a single injection of pilocarpine ; but after extraction of lipoids by hot pyridine and subsequent straining with iron haematoxylin, enlargement (i.e. of the non-lipoid moiety) is shown only after prolonged starvation. A light, uncoloured central area is found in some of the largest granules after feeding and colouring with acid haematein. An acid phosphatase appears in the oxyntic cells whose granules are about to lose their lipine component, and it disappears when they have done so. It is suggested that the acid phosphatase may cause hydrolysis of the phospholipine. Only after prolonged starvation is there any apparent change in granule numbers, when they are decreased.
Interstitial Cells in the Regeneration of Cordylophora lacustris
Authors: Moore Janet
Published: April 2021

An experimental investigation of the induction of regeneration in the 21. hydroid Cordylophora lacustris has been described in an earlier paper (Moore, 1952). The results of the experimental work may be summarized as follows. First, Cordylophora reconstitution masses, made by chopping up unspecialized tissue and piling the fragments into heaps, may regenerate hydranths ‘spontaneously’. An oral cone grafted into a mass induces the development from the tissue of the mass of hydranth regions basal to the oral cone. Regeneration of the mass at points other than the graft site is inhibited.
The Innervation of the Skin of Teleost Fishes
Authors: Whitear Mary
Published: April 2021

A detailed study of the innervation of the skin of teleosts by fibres of the general cutaneous system has demonstrated anatomical differences which may be correlated with the various senses known to be mediated by these nerves. The anatomy of the plexus which these nerves form in the skin is very similar to that of other vertebrates which have been studied. There exist in the epidermis certain elongated cells, which may be isolated sensory cells taking part in the perception of ‘common chemical’ stimuli. It is possible to trace single fibres throughout a considerable part of their course in the skin; a study has been made of the distribution at the surface of the branches of certain fibres of a type which is almost certainly tactile.