i86 
Animal Automatism. 
[April 
his “ Then I awoke, and behold, it was a dream.” In the 
one essay, he traces the progress of an excitation from the 
peripheral end of the afferent nerve to its termination in 
the “ sensifacient ” sensorium ; and in the other, shows how 
the stimulus is reflected through the grey matter of the 
brain or spinal cord to the efferent nerve. These processes 
he describes throughout “ in terms of matter and motion,” 
leaving no room for the intervention of any spiritual Archseus. 
Yet at last we are left in doubt whether this creative cere- 
brum may not after all be a mere phantom, evoked by the 
Archseus itself. 
The whole discussion of Descartes’s theory of “ Animal 
Automatism ” tends to prove that the human organism is a 
self-aCting machine, differing from the lowest forms of life 
only in its greater complexity. It is simply a watch, sup- 
plied with a mechanical contrivance by which it can wind 
itself up and manufacture other watches. We are told 
that “ modern physiology, aided by pathology, . . . proves, 
direCtly, that those states of consciousness which we call 
sensations are the immediate consequents of a change in the 
brain excited by the sensory nerves, and, on the well-known 
effects of injuries, of stimulants, and of narcotics, it bases 
the conclusion that thought and emotion are, in like man- 
ner, the consequents of physical antecedents.” Undoubted 
examples of complicated and seemingly rational reflex aCtion, 
in man and other animals, are dwelt upon at some length ; 
and in order to examine the train of reasoning which runs 
through the greater part of this essay, it will here be neces- 
sary briefly to recapitulate certain well-worn physiological 
faCts. 
If the spinal cord of a human being be divided at any 
point, those parts of the body supplied with sensory nerves 
having their origin below the division are absolutely deprived 
of sensation, but remain capable of apparently purposive 
motions in response to stimuli. The same holds good of a 
frog similarly mutilated, but in this case we are able to carry 
the experiment a step farther. If, without injuring the 
spinal cord, we remove “ the foremost two-thirds of the 
brain,” the animal will jump or walk when irritated, and 
swim if thrown into the water, but is absolutely devoid of 
any spontaneity.” The inference is “ that the impression 
made upon the sensory nerves of the skin of the frog by the 
contact with the water into which it is thrown, causes the 
transmission to the central nervous apparatus of an impulse, 
which sets going a certain machinery by which all the 
muscles of swimming are brought into play in due co- 
