“Thus,” he continues, “a decapitated frog” (here then we have it that the frog’s head was actually cut off) “after the first violent convulsive moments occasioned by the operation have passed away, remains at rest until it is touched; and then the leg, or its whole body may be thrown into sudden action, which suddenly subsides again.” (How does this quiescence when it no longer feels anything show that the “leg or whole body” had not perceived something which made it feel when it was not quiescent?)—“Again we find that such movements may be performed not only when the brain has been removed, the spinal cord remaining entire, but also when the spinal cord has been itself cut across, so as to be divided into two or more portions, each of them completely isolated from each other, and from other parts of the nervous centres. Thus, if the head of a frog be cut off, and its spinal cord be divided in the middle of the back, so that its fore legs remain connected with the upper part, and its hind legs with the lower, each pair of members may be excited to movements by stimulants applied to itself; but the two pairs will not exhibit any consentaneous motions, as they will do when the spinal cord is undivided.” This may be put perhaps more plainly thus. If you take a frog and cut it into three pieces—say, the head for one piece, the fore legs and shoulder for another, and the hind legs for a third—and then irritate any one of these pieces, you will find it move much as it would have moved under like irritation if the animal had remained undivided, but you will no longer find any concert between the movements of the three pieces; that is to say, if you irritate the head, the other two pieces will remain quiet, and if you irritate the hind legs, you will excite no action in the fore legs or head. Dr. Carpenter continues: “Or if the spinal cord be cut across without the removal of the brain, the lower limbs may be _excited_ to movement by an appropriate stimulant, though the animal has clearly no power over them, whilst the upper part remains under its control as completely as before.”