NOTES AND MEMORANDA.*

Diatoms in Coloured Liquids. - Dr. Hamilton L. Smith (U.S.) writes to the Belgian Microscopical Society :-"The communication which exists between the internal protoplasmic substance and the exterior does not take place along the sutures of the connectives, but in Navicula (properly so called) it exists along the raphé or median line of the valves, and in Surirella and Nitzschia along the edges of the wings or of the carinæ.

"I possess some drawings showing the injection of indigo along the median line and its penetration into the interior of the diatom, especially in Stauroneis which had lain some days in water saturated with indigo. Apart from this demonstration, I have been able to obtain, by employing this pigment, an idea of the mode of progression of some large species of Pinnularia.

"On observing a living Pinnularia under the microscope, when the field has been made blue with indigo, and the object is looked at on the valvate side (that is to say, with the median line turned towards the eye), small particles of indigo are seen to run all along this median line and to accumulate near the centre in the form of a small ball or sphere. Looked at from the side of the connective (front view), a ball is seen to form in the centre of each valve; and what is remarkale, each of these small spheres turns on its axis with a tourbillon motion, just as would be the case if a small jet of water issued beneath it from a small orifice situated at the central point of the median line.

"When the balls have attained a certain volume they suddenly burst, and the particles of indigo then proceed with a retrograde motion along the frustule. Immediately after the rupture of the ball, a new one begins to form in the same place. The particles take a given direction, whilst the diatom itself follows the contrary direction. If the motion of the diatom is reversed, the particles of indigo follow an opposite course to that indicated. I have observed this curious phenomenon for hours together, and it was a glorious spectacle. I had in the field of the microscope some magnificent specimens of large Pinnularia, and the phenomenon showed itself specially distinct, when in consequence of a grain of sand or other obstacle the free motion of the frustule was arrested. The colour I used was the ordinary blue indigo water-colour paint, applied in a pretty concentrated form.

"Another observation which I made at that time proved to me the existence of a gelatinous external hyaline envelope to the frustule, which prevented the direct contact of the particles of indigo with the siliceous

*It is intended that each number of the Journal shall in future contain notes of the articles in foreign journals which relate to the microscope or the various subjects of microscopical research. Also notes of new books or new editions and of the contents of the English and foreign microscopical and other journals which can be referred to in the Society's library. The Journal will thus contain a record of the progress of microscopy both in England and abroad, and the Fellows will be able to ascertain from time to time what has been published of interest to them in the various periodicals.

part. When the diatom moved it pushed before it a cordon of particles of indigo, which kept always at the same distance from the anterior portion of the frustule, and which were repelled during the movement of the diatom. A very slight application of red aniline (Fuchsine) demonstrated conclusively the existence of the gelatinous envelope ordinarily invisible; for it colours it distinctly even before the tint has made its appearance in the field of the microscope. Aniline always instantly stops the motion of diatoms with which it comes in contact."

Abnormal Appearances of Hydra viridis.—Mr. Sydney J. Hickson, while examining specimens of this polyp in Professor Lankester's class, University College, noticed one which exhibited twelve or fourteen sperm sacs, although it was budding at the same time. The young budded hydra had one tentacle, with a short oval outgrowth at the tip, giving it a forked appearance, and below the normal row of tentacles was a second row. The parent polyp exhibited a constriction a little way below the tentacular row, and from the constricted part sprang three tentacles, forming an incomplete second row. These three tentacles were more sluggish in motion than the others. In the course of a week the bifid tentacle disappeared, one half having probably dropt off; the sperm sacs increased in size and some burst, and a definite constriction appeared towards the basal end, as if fission were commencing. An unfortunate accident prevented further observations. Mr. Hickson observes that Johnston cites the following passage from 'Baker on the Microscope':--" Instead of buds of little protuberances, the body sometimes pushes forth single tentacula scattered irregularly over it, and these can be metamorphosed into perfect polypes, the base swelling out to become the body, which again shoots out additional tentacles to the requisite number."

Rhizopods in an Apple-tree.-Professor Leidy mentions that while waiting at Swarthmore for the train to return home, his attention was attracted to a large apple-tree which shortly before had been prostrated by a storm. In the fork of the trunk there was a bunch of moss which he collected and took home. On washing the moss and examining the water, he was not a little surprised to find in it many rhizopods. Of these, one was Difflugia cassis, and was abundant. Another was Difflugia globularis, few in number. The others were Trinema acinus, Euglypha alveolata, and Euglypha brunnea. position of these animals, in the moss on the tree, was about eight feet from the ground.*

The

On an Ostracode Crustacean of a new Genus (Acanthopus), met with in the deep Waters of the Lake of Geneva. By M. H. Vernet. This entomostracan cannot be referred to any type hitherto observed in fresh water; it belongs to the marine family Cytherida. Like the representatives of that family, it possesses only a single pair of maxillæ, and, on the other hand, three pairs of feet armed with strong hooks at their basal articulation (the other fresh-water Ostracodes having two pairs of maxillæ and two pairs of legs). The rudimen

* 'Proceedings of the Academy of Natural Sciences of Philadelphia,' Dec. 18, 1877.

tary post-abdomen is reduced to two rounded lobes, each bearing two hairs. The antennæ also much more resemble the type of the Cytheridæ than that of Cypridæ.

The reproductive apparatus does not present anything peculiar; it resembles that of the Ostracodes in general. Besides the sexual tube there is a receptaculum seminis in the female, and a very complicated chitinous copulatory apparatus in the male. The vulvæ are placed below the two post-abdominal lobes.

With regard to its mode of life, this crustacean is unable to leave the bottom. It does not swim at all; it sometimes creeps, but usually buries itself, and thus travels in the mud and organic débris by the aid of its feet and antennæ. The hairs and segments of the feet are driven into the mud, which serves as a support. The strong hooks of the basal articulation are especially useful, but give a somewhat awkward appearance to the mode of progression. The mechanism of this locomotion may be compared to that of a man who endeavours to advance upon his knees, aiding himself with his toes.

The two pairs of antennæ act in opposite directions; their action may be compared to that of the two anterior paws of a mole. These are the members which enable our crustacean to bury itself in the mud.

With reference to the origin of this organism two suppositions may be formed it may be descended from a marine species introduced by some means into our lakes; or it may have for its ancestor a freshwater crustacean; the genus Candona would be that which it most resembles, though nevertheless very dissimilar. The field of hypotheses remains open upon this point.

A Microscopic Trap for a Rover.-Mr. F. A. Bedwell describes in the Midland Naturalist' a very useful contrivance to keep rotifers and other lively things within the field of view. A friend had sent him some specimens of Hydatina senta which he was anxious to examine with a high power. He says:-"I first tried my usual cell, a ring of microscopic glass, the very thinnest I can get (and answering to the No. 6 on the adjustment collar of the ), with a piece of glass as thin as itself over it. This prevented the whirligig performance, but rest was out of the question, and following even Hydatina's charms under a 4, gets monotonous when you are always only just catching her up. So I tried an old idea in a new form. I took a flat glass slide and dropped two Hydatinas on it, with a small drop of water about half an inch in diameter. Upon this drop I laid some cotton wool, frayed out so as to be much diffused in space. I then put the thin sheet of glass on that, gave the sheet a touch with a needle to set the capillary attraction up, and Hydatina's gambols were over. I used an to examine her easily."

High-angled Objectives for Histological Work.-In his address to the Dunkirk (U.S.) Microscopical Society, Professor J. Edwards Smith strongly advocates for histological investigations objectives of very 'Bibl. Univ.,' Oct. 15, 1877. Arch. des Sci.,' p. 334. Ann. Nat. History,' Feb. 1878.

wide ("plus 180°") angle of aperture, and in support of his view refers to an experience in which a friend with an English low-angled glass (50° to 70°) showed "Nasmyth's membrane" in a section of human tooth, which the glass of higher aperture proved to be an optical illusion only. "We often hear the remark," says the Professor, "that wide-angled glasses are just the thing for the display of lined objects, surface markings, diatoms, &c., but that, owing to their short focal length and limited working distance, the trouble attending the adjustment of collar, and in general the difficulties pertaining to their use, they are unsuited to the purposes of the histologist; while, on the contrary, low-angled glasses of greater working distance, requiring no skill in management, are the tools with which the real work of the microscope has been and will continue to be done; and such are fondly termed good, honest, and reliable working glasses.' I can never listen to this line of argument without entertaining the suspicion that sloth and inactivity lie at the bottom. We never hear astronomers complain of the care they are compelled to use in instrumentation; on the contrary, they pride themselves on the accomplishment of being able to work instruments requiring a great amount of skill and precision in manipulation. The objectives of short working distance originated years ago, when German pathologists were in the habit of using common windowglass to cover their mounts, and at that time the extremely thin glass now so easily procurable was unknown.

"A vast amount of work has been done with these 'honest and reliable working glasses,' and will have to be done over again; and this revising work is now in progress."

The Professor also refers to a case in which a sample of urine, from a child supposed to be suffering from a disease of the kidneys, appeared, when examined with a low power (, of 70° aperture), to be in every respect healthy, "but on further examination with a wideangled glass, and with an amplification of nearly 4000 diameters, it was found to be literally swarming with vibriones."

New Process of Colouring Microscopic Preparations with a Picroaniline Solution.*-Whilst engaged on the normal structure of the general lymphatic system, I had occasion to communicate to my colleagues of the Société medico-physique of Florence the good results which I had obtained in my investigations (better than by any other colouring matter) by a solution of aniline blue and of picric acid. I was unable at that time to enter much into details concerning this new and most simple method of staining, having only experimented upon a single tissue, that of the lymphatic system. Now, however, after having, together with Dr. Brigidi, made a large number of observations upon almost all the different tissues, I can speak about the method with more detail, and recommend it to those who are occupied with histological studies.

The two substances which I recommend for producing a very beautiful green colour have been already employed for some time in

* Dr. A. Tafani, in the Journal de Micrographie.'

histology to colour tissues, both normal and pathological. Yet I do not find that anyone, until we did so, made use of these two reagents simultaneously, so as to obtain a composite colour different from that which each produced separately. Everyone knows, indeed, how soluble aniline blue is used as a matter of preference, and to save time, to colour elements and tissues which have been previously submitted to the hardening action of alcohol and chromic acid, although more time is required for those which have been submitted to the action of the latter reagent.

It is also known that certain tissues, such as those of the spleen and the lymphatics, and the cerebral and spinal nervous tissues, retain their colour better and with more elegance when aniline blue is used; that the preparations thus coloured do not lose the tint which they have acquired by the addition of the acids, whilst alkaline solutions and even glycerine affect them in time. A colouring matter possessed of such advantages is, however, but little employed compared with others, such as carmine, hematoxyline, &c.; and I believe the reason to be that preparations coloured by means of aniline blue, although very elegant, do not show all their details so well differentiated and so plainly as can be done with other processes, for example, with picro-carminate. Blue staining, in general, but particularly that produced by aniline blue, will not allow histological forms to be defined in all their details. I might almost say that the contours fail to be recognized, which prevents our distinguishing in a tissue rich in cellules the limits of the various elements.

It is besides well known that picric acid (in a saturated solution) colours the morphological elements and not the amorphous substances (Robin). It follows from this that the tissues which have been submitted to its action take a beautiful yellow sulphur tint, and do not in any way lose the distinctness of their outlines. This is owing to the fact that picric acid is a reagent which does not precipitate in a granular form the substances forming the tissues or elements on which it is made to act, whilst the contours of the nuclei, the nucleoli, the granulation, and the cell-walls do not disappear. Moreover, the action of picric acid is not like that of chromic acid, which enters into combination with the substances upon which it reacts (Ranvier); and it also constantly happens that coloured preparations, after being hardened by the latter acid, are completely deprived of their colour by repeated washings with water. The action of picric acid on tissues is therefore much less detrimental than that of chromic acid.

Whilst then the colouring properties of aniline and picric acid, when they act separately, are sufficiently well known, no one has until now (at least so far as I know) employed these two substances at the same time and on the same tissue, so as to obtain a different tint by their reciprocally modified action, and giving rise to some important peculiarities, especially in certain special tissues.

The idea of using picric acid in combination with another substance to obtain a third, unlike it, and whilst partly possessing the properties of the component substances, also some other new properties resulting from the mixture, is certainly not new, if we refer