We shall see, by and by, that Mr. Abernethy made this and other cases the instruments of much future good; but as we shall not be able to digress from that Summary of our obligations, which we shall then be employed in taking, we will add a few words here in aid of removing that difficulty which some people have in understanding how such dreadful pain can result from any organ in the interior of the body, where no pain is felt at all. In order to do this, it is only necessary to have a clear general notion of the nervous system. If you could take away everything but the nerves, you would have the brain, spinal marrow, and certain knot-like pieces of nervous substance (ganglions, as we term them) from which myriads of cords proceeded, varying in size from the smallest imaginable filaments up to moderate sized cords; the ends of the delicate filaments terminating in the various organs and on the surface of the body; millions of messengers of the most extreme sensibility, by which impressions are telegraphed with the swiftness of lightning between all parts of the body. There is, however, a habit or rule which is ordinarily observed, and that is one of the most curious things in the whole range of physiology—namely, that the immediate cause of our recognition of sensation is never in the part itself, but the action is constantly transferred to the extremity of the nerve. When you strike the ulnar nerve at the elbow (popularly termed, sometimes, the funny-bone), you feel it in the fingers to which its branches are distributed. If you place your finger in cold or warm water, the action that makes you feel it is in the brain; and we infer this, because if we divide the communication between the brain and the finger, you no longer feel the sensation. Now, bearing this in mind, you easily understand how anything disturbing the nerves of any internal organ may produce pain in some distant branch; and that this is really so, many cases of tic doloreux have furnished conclusive and triumphant proofs. Now, as to _why_ it should be seated in this or that particular site, is a question of extreme difficulty; as also in what organ the primary disturbance is seated, supposing it to have been in any of them. The former, I believe, is a question we have yet been unable to solve; the _latter_ may usually be accomplished, _if sufficient pains be taken_. Abernethy, in his lectures on this subject, when observing on the inefficiency of this division of the nerve—which was ministering to effects only—was accustomed to remark, with that peculiar archness of expression which his pupils must so well remember: "I wonder that it never entered into the head of some wise booby or other to divide the nerve going to a gouty man's toe." This was a very characteristic mode of terminating a discussion of any point which he wished to impress on the memory of the pupil. SECTION. OF HIS PAPER ON OCCASIONAL CONSEQUENCES OF BLEEDING.