changes of the textures in fevers and inflammations, but may be able to remove the products of insufficient chemical action even in those diseases which affect the non-vascular textures, as, for example, in cataract and in gout? It remains that I should in a very few words tell you what was already known regarding this fluorescent substance, and on the rate of passage of alkaloids into and out of the body, before we begin our work. In 1845, Professor Brücke stated that the lens absorbed the blue rays of light to a very great extent, and that the cornea and aqueous humour did so to a less extent. In 1855, Professor Helmholtz examined for fluorescence the retina of the eye of a man who had been dead for eighteen hours. The first experiment showed that it was very feebly fluorescent. The colour of the light dispersed through the retina he found greenish-white. In 1858, M. Jules Regnauld, using sun light, found in man and the mammifera that the cornea fluoresced in a very slight degree. In the sheep, dog, cat, and rabbit the crystalline lens possessed in the highest degree fluorescent properties. In these animals, and also in many birds, the central part of the lens, preserved by dessication at a low temperature, retained this property. The central portion of the crystalline of many aquatic vertebrata and mollusca he found almost entirely without fluorescence. The vitreous humour possesses only a very feeble fluorescence, due to the hyaline membrane. The retina possessed a certain fluorescence which was not at all comparable in intensity to that of the crystalline lens. In 1859, I. Setschenow, of Moscow, a pupil of Helmholtz, at his request, experimented on the eyes of men and rabbits. The fresh retina showed the same phenomenon as the dead human retina. It diffused a greenish-white light, which, examined by a prism, gives a spectrum in which the red is wanting. The vitreous humour in a thin glass vessel showed only traces of fluorescence. The lens, on the contrary, fluoresced very strongly, the colour of the dispersed light being whiteblue, exactly like quinine, only the quinine was a little stronger. Examined by a prism, the dispersed light gave a spectrum in which the red was wanting, and in which the blue-tone predominated. The fluorescence begins as in quinine solutions between G and H, and is strongest at the outer edge of the violet rays, and extends into the ultra violet to the same distance in the case of the lens as in the case of the quinine solution. When the cornea was cut out, it fluoresced much feebler than the lens; the aqueous humour did not fluoresce at all. The appearances in the three last media, he says, can be shown with the greatest ease, even in the eye of the living man. When the eye is brought into the focus of the ultra violet rays immediately the cornea and the lens begin to glimmer with a white blue light. The cornea in the living eye is much more fluorescent than when dissected out, probably from the loss of transparency, consequent on contraction of the texture, and from evaporation. Vol. IV. (No. 43.) 2 T Professor Donders has carefully investigated the time in which atropine and Calabar bean act on the iris in man. A solution of atropine dropped on the cornea in 15 minutes begins to act, and attains its maximum in from 20 to 25 minutes. In 42 hours the pupil is rather smaller, and even after 13 days the pupil was not quite its natural size. The fluid extracted from the aqueous humour, injected into another eye, caused dilatation of the pupil. A solution of Calabar bean began to act in from 5 to 10 minutes; attained its maximum in from 30 to 40 minutes. At the end of three hours it began to diminish, and disappeared entirely in from two to four days. [H. B. J.] GENERAL MONTHLY MEETING, Monday, April 2, 1866. SIR HENRY HOLLAND, Bart. M.D. D.C.L. F.R.S. President, John Curwen Christian Boyd, Esq. Charles Browne Cornish-Browne, Esq. Walter Thomas Fawcett, Esq. Mrs. Bridget Margaret Sortain. were elected Members of the Royal Institution. The Special Thanks of the Members were returned to EDWARD OWEN TUDOR, Esq., for his Contribution of 217. to "the Donation Fund for the Promotion of Experimental Researches" (see page 151). The PRESENTS received since the last Meeting were laid on the table, and the thanks of the Members returned for the same, viz. :— British Museum Trustees-Catalogue of Seals and Whales. 8vo. 1866. 1866. British Architects' Institute, Royal-Sessional Papers, 1865–6. Part II. No. 4. 4to. Chemical Society-Journal for Feb. 1866. 8vo. Dublin Society, Royal-Journal, No. XXXIV. 8vo. 1865. Geological Society-Quarterly Journal, No. 85. 8vo. 1866. Geological Survey (through Sir R. I. Murchison, Bart.)-Memoirs, 8 Parts. 8vo. British Organic Remains. Decade 10, 11, and Monograph 2. 4to and 8vo. Mineral Statistics. 1859, 1862, and 1864. 8vo. Seven Catalogues. 8vo. Horticultural Society, Royal-Proceedings, 1866. No. 3. 8vo. Journal, Vol. I. No. 2. 1866. 8vo. Literary and Philosophical Society of Liverpool-Proceedings, No. XIX. FiftyFourth Session, 1864-5. 8vo. Mechanical Engineers' Institution, Birmingham-Proceedings, Aug. 1865. Part 2. Svo. Photographic Society-Journal, No. 167. 8vo. 1866. Pritchard, Rev. C. M.A. F.R.S. (the Author)-Eloges of Sir W. R. Hamilton and 1865. Royal Institution of Great Britain. 1866. WEEKLY EVENING MEETING, Sir HENRY HOLLAND, Bart. M.D. D.C.L. F.R.S. President, EMIL DU BOIS-REYMOND, Professor of Physiology in the University of Berlin. On the Time required for the Transmission of Volition and Sensation through the Nerves. Introduction. The speaker first pointed out a certain similarity of action between the nerves and telegraph-wires. Just as little as telegraph-wires, do the nerves betray by any external symptom that any or what news is speeding along them; and, like those wires, in order to be fit for service, they must be entire. But, unlike those wires, they do not, once cut, recover their conducting power when their ends are caused to meet again; in fact, every injury by which the organic structure of the nerve is impaired, such as bruising it between the blades of a forceps or by a ligature, or burning it, or corroding it by some chemical substance, will stop the transmission of either the influence of the will upon its central, or of the impressions of external objects upon its peripheric end. This was illustrated by placing the sciatic nerve of a frog, still attached to the gastrocnemius muscle, on three electrodes, A, B, C— A being the remotest from, and C the nearest to, the muscle. A being connected with one end of a self-acting induction apparatus, and either B or C with the other end, a strong tetanus of the muscle ensued, and was rendered visible by the raising of a little mica flag;* but after a ligature had been tightened around the nerve between Band C, which was simply done by pressing down a lever,† the tetanus was See the description and drawing of the apparatus in Beschreibung einiger Vorrichtungen und Versuchsweisen zu elektrophysiologischen Zwecken.' Von E. du Bois-Reymond. Abhandlungen der K. Akademie der Wissenschaften zu Berlin, 1862, S. 141 ff. The apparatus used is described and figured in Untersuchungen über thierische Elektricität.' Von E. du Bois-Reymond. Bd. ii. Abth. i. Berlin, 1849, S. 341; Taf. iii. Fig. 109, 110. 2 U VOL. IV. (No. 44.) |