28 BIOLOGY AND SOCIAL PROBLEMS 



cortex quickly subsides, and with this sub- 

 sidence consciousness gives place to uncon- 

 sciousness. Thus, even a mind stored with rec- 

 ollections lapses into unconsciousness when, 

 under appropriate conditions, the flow of new 

 material from without is largely reduced. Not 

 only does the inflow of sensory impulses thus 

 condition the activity of the normal mind, but 

 it has also been found to be of like importance 

 in certain abnormal cases. Striimpell's boy 

 was a defective who was insensitive to touch, 

 had no muscular sense, no taste, or smell, or 

 sense of pain, and was deaf in the right ear 

 and blind in the left eye. His sensory impulses 

 were received therefore, chiefly if not exclu- 

 sively, through the left ear and the right eye. 

 If the left ear was stopped and the right eye 

 bandaged, so that the sensory inflow practi- 

 cally ceased, he passed in a few minutes into 

 what seemed to be a state of sleep, thus dem- 

 onstrating the significance of the current from 

 the sense organs for his mental life. The ab' 

 normal, as well as the normal, thus gives evi- 

 dence of the general conclusion that, though 

 the mode of operation of the mind may be 

 determined by the inborn structure of the 

 brain, the content of the mind is supplied 



