Removal of the cerebrum has been repeatedly practised also upon the rabbit and the guinea-pig. The mutilated rabbit sits motionless whilst undisturbed, starves in the midst of plenty, cries out with its peculiar pathetic scream when pinched, draws back when ammonia is put to its nostrils; in a word sees, hears, feels in the same sense as does the pigeon, and, like the pigeon, undisturbed remains passive until death. Tread, however, upon the rabbit's foot, and perhaps with a little scream it darts forward in a furious race. Once started, it, like the brained fish, does not stop until exhausted or until it has dashed its head against some obstruction, for, unlike the mutilated fish, it does not have the power of avoiding obstacles.
Such are the phenomena which in the various species of animals follow the removal of the true brain. Many of the acts are seemingly so purposive, and certainly so complicated, as to suggest that they must be conscious. It has, however, been shown that the fact that an act is apparently purposive and complicated does not prove that it originates in consciousness, and certainly in the brainless animal the past, present and future have been blotted out. There is absolutely no conscious memory, else the needed food would be taken when offered and spontaneous movements would occur. It is hard to conceive of consciousness without memory, and it is certain that no purposive act can be directed by consciousness when memory does not exist in any degree or form. If all memory be lost, though consciousness be preserved, that consciousness would not have the knowledge which should enable an animal to perform a complicated purposive act; nor could it acquire knowledge by experience, because each movement would be forgotten as fast as produced. The phenomena exhibited by the brainless animals must therefore rest upon some other basis than consciousness. The first point to be observed in looking for this basis is that movements never occur so long as there is no external irritation. The frog, the pigeon, the rabbit, all maintain the same absolute repose unless the impulse comes from without. The fish is a seeming, but not a real, exception to this rule. The frog, the pigeon, the rabbit, all are quiet on the land, because their surface is not irritated: the fish in the water rushes forward, because the play of the liquid is all the time irritating the exterior of the body. Throw the frog into the water, and it is seized with the madness of the fish; toss the pigeon in the air, and it dashes forward; set the rabbit once in motion, and its course also is a headlong fury. Placed under parallel conditions, these various animals exhibit parallel phenomena, and remain quiet unless disturbed by surface-irritations. The facts show that for action in the animal whose upper brain has been removed some external irritation must generate the impulse, which travels upward to a nerve-centre, and then brings into activity certain masses of nervous tissue (ganglia), which, thus aroused, send impulses out to the various muscles without the intervention of consciousness. Movements generated in this way are _reflex_ or _automatic_. In brainless[2] animals the reflex actions are not different in their essence, but only in their degree, from those performed in the frog with a cut spine; or, in other words, the acts originating in the lower brain are reflex and similar to those arising in the spinal cord, only more complicated and more apparently purposive.