It is hardly without a smile that we resuscitate the old question of the 'vis insita' of the muscular fibre, so famous in the discussions of Haller and his contemporaries. Speaking generally, I think we may say that Haller's doctrine is the one now commonly received; namely, that the muscles contract in virtue of their own inherent endowments. It is true that Kolliker says no perfectly decisive fact has been brought forward to prove that the striated muscles contract without having been acted on by nerves. Yet Mr. Bowman's observations on the contraction of isolated fibres appear decisive enough (unless we consider them invalidated by Dr. Lionel Beale's recent researches), tending to show that each elementary fibre is supplied with nerves; and as to the smooth muscular fibres, we have Virchow's statement respecting the contractility of those of the umbilical cord, where there is not a trace of any nerves. In the investigation of the nervous system, anatomy and physiology have gone hand in hand. It is very singular that so important, and seemingly simple, a fact as the connection of the nerve-tubes, at their origin or in their course, with the nerve-cells, should have so long remained open to doubt, as you may see that it did by referring to the very complete work of Sharpey and Quain (edition of 1849), the histological portion of which is cordially approved by Kolliker himself. Several most interesting points of the minute anatomy of the nervous centres have been laboriously and skilfully worked out by a recent graduate of this Medical School, in a monograph worthy to stand in line with those of Lockhart Clarke, Stilling, and Schroder van der Kolk. I have had the privilege of examining and of showing some of you a number of Dr. Dean's skilful preparations. I have no space to give even an abstract of his conclusions. I can only refer to his proof of the fact, that a single cell may send its processes into several different bundles of nerve-roots, and to his demonstration of the curved ascending and descending fibres from the posterior nerveroots, to reach what he has called the longitudinal columns of the cornea. I must also mention Dr. Dean's exquisite microscopic photographs from sections of the medulla oblongata, which appear to me to promise a new development, if not a new epoch, in anatomical art.