POISONS OF THE INTELLIGENCE. 739 



mind excites, through the spinal cord, the various muscles, produc- 

 ing movement ; but this condition is not absolutely necessary, since 

 in decapitated animals, for instance, the nervous system of the spinal 

 cord can of itself produce motion of the muscles. Here we have 

 motor activity, but no sensibility. Sensibility exists only where the 

 mind is intact and capable of perceiving, so that a creature which has 

 no mind is void of sensibility. This fact is confirmed by pathologi- 

 cal observation ; for, whenever the mind is affected, there appear at 

 the same time symptoms of disordered sensibility, and vice versa. 

 And when we find a patient exhibiting notable disorder of the sensi- 

 bility, then, if the nerves are intact, we can safely conclude that the 

 central nervous system is affected, and to that degree that the mind 

 has not escaped. 



Anatomy and physiology here are in accord with pathology. Some 

 animals possess little or no sensibility : they belong to the lower 

 grades of animals ; their intelligence is obscure, and their sensibility 

 is as obtuse as their intelligence. On the other hand, if we consider 

 animals of higher intelligence, we find their sensibility becoming more 

 and more keen, till we come to man, at once the most intelligent and 

 the most sensitive of animals. And even in man himself we find race- 

 differences, those races being most sensitive which possess the highest 

 decree of intelligence. The anatomical structure of the nervous cen- 

 tres is in harmony with this coincidence, for it is in man that the pos- 

 terior columns of the spinal cord are most voluminous, as compared 

 with the anterior. Now, the anterior columns transmit the motor 

 excitations to the nerves, while the posterior columns transmit the 

 sensory excitations. Again, the posterior lobes of the brain in man, 

 as compared with animals, are more developed than the anterior. 

 But it is in the posterior lobes that perception of sensitive excitations 

 appears to reside. 



Nor is it surprising that there should exist so intimate a relation 

 between mind and sensibility. Indeed, whatever may be the influence 

 of the spontaneous development of the mind itself, resulting from the 

 constitution of the brain, which is its organ, it still holds true that all 

 our knowledge comes from our sensations, and from the brain-work 

 thence resulting. Mind is, so to speak, the product of these two fac- 

 tors ; and our notions of the world around us, elaborated and fecun- 

 dated by the mind's spontaneous action, constitute individual person- 

 ality. Hence, inasmuch as anatomy, physiology, and pathology, show 

 intimate relation between sensibility and intelligence, we can justly 

 say that psychology confirms the positive data furnished by these 

 three sciences. 



Accordingly, poisons which affect the intelligence are ipso facto 

 poisons of the sensibility. In this respect alcohol does not differ from 

 chloroform. When alcoholic intoxication is only beginning, we find 

 already a notable degree of insensibility ; but at the comatose stage 



