The legs of these frogs, examined by the metals both before and after their separation from the body, were found in a state very different from those before spoken of. The contractions were scarcely perceptible. The incisions made through the skin, in order to get at their nerves, had closed completely in less than a week after they had been made. The appearance of the muscles in the legs, whose nerves had been divided, was found to be precisely the same as in those where nothing had been done; but, notwithstanding this circumstance, even strong electrical sparks excited but very feeble contractions. On examining the nerves, the ends of that which had been longest divided were found connected by a substance not at all resembling nerve, but similar to that found in the former experiment, and evidently proceeding from the upper division. In the nerve which had not been so long divided, this circumstance was still more apparent, as the substance had not extended quite to the lower division. The cellular membrane surrounding these upper divisions had the appearance of innumerable vessels finely injected, and some red streaks were seen projecting, as if from the nerve itself, into the gelatinous production. In the sound nerves, the obliquely transverse lines of alternate opacity and transparency, or, as Fontana has called them, the white spiral bands of nerves, were seen distinctly at the first glance of the eye, and without the assistance of a glass; but no appearance of these could be found in the parts of the divided nerves below the division; these were uniformly opaque. Their bulk, however, was not in the least diminished. The organization of nerves long divided, therefore, undergoes a very evident alteration, although it is by no means so clear that the same change happens in the muscles, to which these nerves are distributed. Yet their susceptibility to the action of electricity, as well as to that of this new influence, was nearly lost. Some may consider this as an additional argument, that stimuli act upon muscles only through the medium of nerves. I have before observed that muscles of frogs, from whom the skin has been stripped, become in a short time hard when exposed to the action of water. Wishing, therefore, to see if there would be any difference between these legs, whose nerves had been divided, and others, in this respect, I laid them in water, and examined them every ten minutes, but both became hard nearly at the same time. Mr Allen, a gentleman well versed in physiological pursuits, was with me when I examined the alteration which had taken place in one of these nerves, in consequence of its having remained long divided, and I had afterwards an opportunity of shewing it to Dr Rutherford. In all the frogs, whose nerves I have divided, I have observed that the divided extremities, though placed in most exact contact from each other, had after a time receded at least 1/12 of an inch from each other.