perfectly discoloured, and finally dissolved. During this process it happens that in some instances another delicate double contour is observed inside of that representing the membraneous layer (Fig. 33). This phenomenon may be explained by supposing the surface of the contracted protoplasm to have been rendered more dense by the action of the hydrate of chloral than the rest of the mass, in consequence of which it may resist longer the continued and subsequent solvent action of the reagent, and manifests itself like the membraneous layer of the blood-corpuscle in the form of a double contour. But it also disappears finally by the continued action of the reagent, and nothing but the original double contour representing the membraneous layer is left.

Exposing the blood-corpuscles of the Amphiuma to the action of nitric acid vapour for about two minutes, the following changes are observed to take place. At first, while retaining their colour, they are rendered very distinctly granular. Gradually becoming paler, they are finally entirely discoloured, retaining a delicate finely-granular appearance with a distinct double contour of a greenish tint (Fig. 34). They retain their natural size, and most of them also their oval form. None of them are observed with folds; and as blood-corpuscles with some folds or wrinkles are met with in most specimens of fresh blood, it may be supposed that this reagent renders them smooth again. The nucleus is coarsely granular, almost natural, though more distinct.

In applying the nitric acid liquid to a specimen of fresh blood, the changes taking place in the structure of the blood-corpuscles are very striking. The granules in the interior of the nucleus become dissolved, causing this body to swell and appear cloudy, while its wall is rendered very distinct. The protoplasm appears in the form of a network, with larger and smaller round, oval, or angular meshes, which in some cases are arranged in a radiating form; the largest at the inner surface of the membraneous layer, the smaller ones near the nucleus (Fig. 35). The double contour, representing the membraneous layer, remains distinct from the coagulated protoplasm, and in many corpuscles an interspace occupied as it seems by some fatty material exists between these two parts, or between the protoplasm and the nucleus. The form of the greater part of the blood-corpuscles has become irregular,

and their size reduced.

Nitric acid diluted with equal parts of water produces almost the same changes in the blood-corpuscles as when applied pure. The granules within the nucleus are not always found dissolved, nor are the interspaces between the protoplasm and the membraneous layer or the nucleus met with so frequently (Figs. 36 and 37).

Ether causes the colouring matter of the blood-corpuscles to

escape into the liquor sanguinis until they become perfectly pale, while the nucleus is rendered more distinct. The double contour of the corpuscle appears faint, though distinct. In many instances the contour appears wavy, indicating a contraction of the membraneous layer (Fig. 38). The colouring matter escaped into the liquor sanguinis also disappears finally, while the latter is rendered granular by the action of the ether.

(To be continued.)

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.

66

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. The position of these animals, in the moss on the tree, was about eight feet from the ground.*

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 Cytheride than that of Cypride.

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, 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.