Lansdell, Rev. Henry, D.D. Lockwood, Charles Barrett, F.R.C.S. Smith, Rev. Frederick John, M.A. Love, Augustus Edward Hough, Stewart, Professor Charles, M.A. Lydekker, Richard, B.A. McConnell, James Frederick Parry, Minchin, Professor George M., M.A. Ord, William Miller, M.D. Reade, Thomas Mellard, F.G.S. M.R.C.S. Stirling, William, M.D. Stuart, Professor T. P. Anderson, M.D. Sutton, J. Bland. Swan, Joseph Wilson. Thomson, Professor John Millar, Truman, Edwin Thomas, M.R.C.S. Veley, Victor Hubert, M.A. Whymper, Edward, F.R.G.S. Windle, Bertram Coghill Allen, Woodward, Horace Bolingbroke, Wynne, William Palmer, D.Sc. The following Papers were read :— I. "Preliminary Note on Bilateral Degeneration in the Spinal Cord of Monkeys (Macacus sinicus) following Unilateral Lesion of the Cortex Cerebri." By E. L. MELLUS, M.D. Communicated by Professor V. HORSLEY, F.R.S. Received December 22, 1893. (From the Pathological Laboratory of University College, London.) Having for some time been engaged in an investigation of the question as to how far the fibres of each pyramid descend both halves of the spinal cord, I am in a position to state that in the bonnet monkey (Macacus sinicus) the following arrangement prevails. Method of Investigation.-The animal being etherised, and the left hemisphere of the brain exposed by a single trephine hole (sometimes enlarged afterwards), a small portion of the excitable area of the motor cortex was selected as detailed below, the selection being confirmed in each case by electrical stimulation. A small piece of the cortex, about 04 cm. square, constituting the focus of the movement observed, was removed, care being taken to remove also a little of the underlying corona radiata to be sure that no cortex was left. The wounds healed, without exception, within 24 hours by first intention. Beyond slight paresis, which generally disappeared in 24 hours, no symptoms were observed to result from the excision. Professor Horsley kindly did the operations for me. After three weeks the animals were killed, the brain and cord hardened in Müller's solution, and stained in osmic acid after the method of Marchi. Results of Investigations. Three foci of representation were selected for excision, the left hemisphere being chosen in every case (vide Method of Investigation). I. Focus for the movements of the thumb. II. Focus for the movements of the hallux. The course taken by the descending degenerated fibres was as follows: : 1. Hallux Focus removed.-In this case the lesion consisted of the removal of about 16 sq. mm. of cortex between the superior precentral sulcus and the fissure of Rolando, and bounded below by the level of the superior frontal sulcus. Degenerated fibres were found in both lateral columns of the cord, the large majority being on the right side. The degenerated fibres were scattered throughout the entire area of the crossed or lateral pyramidal tract, not being restricted to any special part of it, though it might be said they were a little more dense posteriorly. Throughout the cervical, dorsal, and lumbar regions the total number of degenerated fibres was not diminished, though, of course, relatively increased in the lower cord. In the pons and medulla the degeneration was entirely confined to the left pyramidal tract (the side of the lesion). At the decussation in the upper cervical region the degenerated tract divided; about one-third going to the lateral column of the same side, the remaining two-thirds crossing to the lateral tract on the opposite side. In the upper cervical region there were a very few degenerated fibres remaining in the direct tract (anterior column), and below the middle of the cervical enlargement none could be seen. II. Thumb Focus removed. In this case the lesion consisted of a similar removal of cortex at a point just above the lower end of the intra-parietal sulcus, and between it and the fissure of Rolando, and, consequently, just behind the inferior genu of the fissure of Rolando (Beevor and Horsley). As in the case of the hallux focus, degeneration was also confined to the pyramidal tracts of the same side (left) as the lesion, throughout the pons and medulla. At the decussation of the pyramids there was also a slight division of the degenerated fibres, but in this case a few fibres only (less than one in ten) went to the lateral column of the same (left) side of the cord. There may have been two or three degenerated fibres left in the direct tract after the decussation, but this could not be positively stated. In the cervical and upper dorsal regions the degenerated fibres gradually decreased in number. At the level of the second dorsal there were a very few degenerated fibres still left in each lateral column. At the third dorsal they had entirely disappeared. It seems probable, from these observations, that a second decussation lower down in the cord-recrossing-does not occur, and that the bi-lateral degeneration observed by Pitres, Sherrington, Langley, Muratoff, and others is a genuine bi-lateral descent of fibres from one hemisphere. II. "On the Relations of the Secular Variation of the Magnetic Declination and Inclination at London, Cape of Good Hope, St. Helena and Ascension Island, as exhibited on the Magnetarium." By HENRY WILDE, F.R.S. Received February 19, 1894. In a paper which was read before the Royal Society in June, 1890, I showed that the principal phenomena of terrestrial magnetism and Cape of Good Hope and St. Helena. The object of the present communication is, firstly, to make a more direct comparison of the declination periods at London and at the Cape of Good Hope than was set forth in my former paper; and, secondly, to show a further agreement between the indications of the magnetarium and the results of recent observations of the dip and declination at the Island of Ascension. The rate of backward rotation of the internal electro-dynamic sphere, as I have said, is 22.5 minutes 0.375° annually. Now, the period of the westerly march of the declination needle at London from zero in the year 1657 to its maximum of 24° 30′' in the year 1817 is 160 years; therefore, 0.375° x 160 = 60° of differential rotation of the internal sphere. Again, the westerly march of the needle at the Cape of Good Hope from the year 1609 to its maximum of 30° in the year 1881 is 272 years. Therefore, 0.375° × 272 = 102° of differential rotation of the internal sphere. Hence, 60°: 160 years: 102° : 272 years; the outward westerly declination periods at London and the Cape of Good Hope respectively, as shown by observation and on the magnetarium. Subjoined are tables of the declination and inclination at London, the Cape of Good Hope, and on the magnetarium for the same epochs. Table I.-Secular Changes of the Declination and Inclination |