218 ANIMAL AUTOMATISM. [LECT. 



system which lies beyond the injury is cut off from 

 consciousness. It must indeed be admitted, that, if 

 any one think fit to maintain that the spinal cord 

 below the injury is conscious, but that it is cut off 

 from any means of making its consciousness known 

 to the other consciousness in the brain, there is no 

 means of driving him from his position by logic. 

 But assuredly there is no way of proving it, and in 

 the matter of consciousness, if in anything, we may 

 hold by the rule, " De non apparentibus et de non 

 existentibus eadem esfc ratio." However near the 

 brain the spinal cord is injured, consciousness remains 

 intact, except that the irritation of parts below the 

 injury is no longer represented by sensation. On the 

 other hand, pressure upon the anterior division of the 

 brain, or extensive injuries to it, abolish conscious- 

 ness. Hence, it is a highly probable conclusion, that 

 consciousness in man depends upon the integrity of 

 the anterior division of the brain, while the middle 

 and hinder divisions of the brain, and the rest of the 

 nervous centres, have nothing to do with it. And it 

 is further highly probable, that what is true for man 

 is true for other vertebrated animals. 



We may assume, then, that in a living vertebrated 

 animal, any segment of the cerebro-spinal axis (or 

 spinal cord and brain) separated from that anterior 

 division of the brain which is the organ of conscious- 

 ness, is as completely incapable of giving rise to 

 consciousness, as we know it to be incapable of carry- 

 ing out volitions. Nevertheless, this separated seg- 

 ment of the spinal cord is not passive and inert. On 



