Its iodo-sulphate is deep olive-green in its reflected tint, orangeyellow by transmitted light, and possessing in an eminent degree optically doubly absorbent powers, thin laminæ being quite black, but still thinner ones give a bistre-brown "body-colour" when polarized perpendicular to axis.

This alkaloid was also furnished me by the kindness of Mr. Howard, but has not yet been sufficiently purified, or in the quantity necessary to give certain results.

It possesses one very peculiar property. When dissolved in chloroform and evaporated spontaneously on glass, the gummy and uncrystalline residue, mounted in Canada balsam, at once shows a deep blue-green, epipolic, or fluorescent appearance.

Pure cinchonidin does not possess epipolic dispersion and does not become green by chlorine-water and ammonia; and when it is dissolved in acetic acid or chloroform and the fluid is exposed on glass plates to spontaneous evaporation, beautiful crystals in circular spots or drusæ develope themselves, which under polarized light exhibit black crosses and white or coloured sectors.

These appearances are not exhibited by pure quinine or true quinidin (3-quinine), both of which give a gummy, uncrystalline, and perfectly transparent residue.

Pure cinchonidin, thus optically and chemically distinguishable from either quinine or quinidin, is still further remarkable for producing with sulphuric acid and iodine an optical doubly absorbent compound of intense power, even equal to the sulphate of iodoquinine compound; these crystals are very similar in form to my artificial tourmalines, and have long been mistaken by me for them; even at present I can only distinguish them by the tints in reflected light and the complementary body-colour, viz. whilst sulphate of iodo-quinine gives a cantharidin-green reflected tint, and a pink, ruby-red, reddish-brown or black body-colour when polarized perpendicular to the axis, according to the thickness of the plate examined, the sulphate of iodo-cinchonidin is golden-green by reflected light, and gives a sky or indigo-blue or black "body-colour" when polarized perpendicular to the axis. I have not yet made sufficient chemical analyses of this substance to enable me to decide on its formula, but I have obtained 39-307 per cent. iodine and 8.864 per cent. sulphuric acid, which sufficiently indicate a chemical difference in constitution

from the sulphate of iodo-quinine, which, it may be remembered, contains 32.609 per cent. iodine and 10.61 per cent. sulphuric acid. I hope soon to present these results in more detail when sufficient leisure is afforded me for the

purpose.-W. B. H.

January 29, 1857.

Major-General SABINE, Treas. and V.P., in the Chair.

The following communications were read :

I. "On the Nervous System of Lumbricus terrestris." By J. LOCKHART CLARKE, Esq., F.R.S. Received Dec. 18, 1856.

(Abstract.)

In the summer of 1855, with the view of throwing some light on other researches in human anatomy, in which he was already engaged, the author undertook some anatomical inquiries on the nervous system of Invertebrata; but finding them occupy more time than he could spare, he was compelled to relinquish the pursuit after having made many interesting but desultory observations on various animals. As he had proceeded, however, to a considerable extent with the nervous system of Lumbricus terrestris, and discovered in it much that is important and was hitherto unknown, he has thought it expedient to resume and complete this portion of the subject without further delay.

Before treating of the nervous system it was necessary,—in order to show the proper functions of many of its parts,-to give some account of the organs of prehension, deglutition and digestion; and as these are insufficiently explained elsewhere, the author has described them entirely from his own dissections and observation.

The first anterior segment is a conical or nipple-shaped projection inserted behind into the upper fifth of the second segment, or first ring. Its dorsal surface is covered, except in the centre, by concentric laminæ and irregular masses of pigment-granules, which are interspersed with large, peculiar and nearly pellucid cells. Its under part forms

a soft and delicate pad, or upper lip, and is continuous at the sides with the inferior half of the second segment, or under lip, to complete the oral orifice from which the mucous membrane of the mouth is reflected inwards. The mouth is a wide tube surrounded by a delicate muscular coat, and attached to the outer tube, or rings, by fine muscular bands. Behind, it dilates into a capacious heart-shaped sac, of which the roof or upper wall is covered by a thick oval muscular mass. The outer portion of this mass is divided into distinct, radiating, digital muscles which connect it on all sides and are continuous with the longitudinal muscles of the rings. Its inner surface projects anteriorly into the cavity of the pharynx, in the form of a thick circular disc or sucker, surrounded by loose folds of mucous membrane. Opening into the sides of the mouth and pharynx are two or three sets of salivary glands, which consist of convoluted tubules, resembling those of Lepidopterous insects: these glands have not been hitherto detected in Lumbricus terrestris. The pharynx contracts into a comparatively narrow œsophagus, which in its turn dilates into a capacious crop; and this immediately opens into a cylindrical gizzard composed of a ring of cartilage, with an external muscular coat, and a lining of mucous membrane. A long straight and narrow intestine extends through the rest of the body, and is covered throughout with yellow, follicular, hepatic glands in circles corresponding to the segments.

Nervous System.--The central organs of the nervous system consist chiefly of a bilobed cephalic ganglion, and a double chain of subventral ganglia extending through the whole length of the body. The lateral lobes of the cephalic ganglion are pyriform, and united by their broader ends in the mesial line. The small end of each divides into two nerve-trunks, of which one forms the root of its cephalic nerves, and the other, the pharyngeal crus, which curves round the side of the pharynx to join the first subventral ganglion. Each crus gives off eight or nine branches. The first four or five arise from the under part of its anterior half, and immediately enter the upper surface of a minute and delicate cord-like chain of ganglia, the enlargements of which correspond to them in number and size. This highly interesting structure lies on the side of the pharynx, concealed beneath the crus. The breadth of its first ganglionic enlargement in a good-sized worm, was the 6th of an inch; that of the

last theth; the pharyngeal crus, where their roots come off, was th of an inch in diameter. Each border of the chain gives off several trunks of considerable size, which immediately communicate to form a continuous plexus. The part of the plexus on the inner side is much the larger, and supplies anteriorly, the muscular and mucous coats of the mouth as far as the lips; and posteriorly, the pharynx and suctorial disc; uniting in both directions with its fellow of the opposite side. The outer part supplies the muscular bands From the pharynx, the plexus descends along the side of the œsophagus, lying on the abdominal vessels, and communicates with minute filaments from the nerves of the subventral ganglia.

and salivary tubules.

The whole of this little chain with a large portion of its plexus and the wall of the pharynx on which it lies, was removed and examined under a 4th-inch object-glass, when a beautiful and unexpected appearance was observed. The under surface of the entire chain-cords as well as ganglia-was covered with a lamina of round, oval, and pyriform cells; and on its upper surface a row of cells of the same kind was found along each border. At every point of communication between the branches which form the plexus, a minute ganglionic enlargement was observed, from which new branches proceeded to form other enlargements of the same kind. Every branch communicated by loops with those adjacent, and by transverse fibres with those of the opposite side, giving to the ganglionic points a kind of stellate appearance. In these microscopic ganglia, the nerve-cells, similar to those of the chain, were accumulated chiefly about the angles, along the borders, and extended some distance into the principal trunks; but very few could be seen in connexion with nervefibres, which ran around and between them, however, in an intricate manner. As the plexus extended from the chain, the ganglionic points diminished in size, while the smaller branches given off from the trunks increased in number, and communicated like a capillary network. At the same time the ultimate fibres became paler, flatter, more parallel, and acquired nuclei like those of cells. This was particularly observed in those distributed to the mucous membrane. The above observations were repeated on nearly forty different specimens.

On considering the parts which it supplies, this little chain appears to combine the office of a sympathetic with certain other functions

which in many Invertebrata are entrusted to separate and special centres ;-such as the labial, pharyngeal, and visceral ganglia in Cephalopodous and Gasteropodous Mollusca, and the separate parts of the stomato-gastric system of insects, which, although derived from different sources, are in intimate communication with each other. The lateral ganglia in insects have the same position as the little chain of Lumbricus, on the side of the pharynx, which, according to Mr. Newport, is supplied entirely by them; they arise, however, wholly from the cephalic ganglion, while the chain in Lumbricus has just been seen to take its origin both from this and the pharyngeal collar; but then, in orthopterous insects, the gangliated recurrent nerve, which is always in intimate connexion with the lateral ganglia, arises entirely from the pharyngeal crus; and the fact has been observed by Burmeister, Brandt and Müller, that in some other orders these two parts, in regard to size, are in the inverse ratio of each other. In Crustacea also, the whole of the pharyngeal, gastric and visceral nerves take their origin from the crura, as was first shown by Audouin and Milne-Edwards.

The second set of nerves from the pharyngeal collar come off from its posterior half, and communicate with each other by loops before they leave it. The first and largest sends some filaments to the muscular bands of the mouth, upon which they communicate by evident but slight dilatations with the plexus of the pharyngeal chain; and after supplying the muscles of the anterior segments, are lost in the integument of the lower lip. The rest take nearly the same course. But what is extremely interesting, the roots of this set-at least of the first and second branches-are continuous across the crus with those of the former set which belong to the pharyngeal chain; and many of their fibres may be traced not only into its ganglia, but through the trunks which proceed from their opposite sides to form the pharyngeal ganglionic plexus; so that the nerves distributed to the labial muscles and integument of the outer tube, and those which supply the inflected oral and pharyngeal tube, are in direct continuity, not only at their peripheral extremity, but at their roots also, through the common centre which presides over the whole of the digestive apparatus. A similar connexion will be seen to exist with regard to the cephalic nerves.

The subventral chain is a double cord gangliated at short intervals