178 CHEMICAL CORRELATION 



cerned, goes back of the characters themselves to the 

 glands in which the hormones are manufactured. To 

 illustrate, the straight black hair and reddish skin of 

 the American Indian, as contrasted with the yellow hair 

 and fair skin of the Northern European races, are due, 

 according to this view, to differences in hormones, but 

 the differences in hormone production are themselves 

 inherited. 



Summary. — Through the combined action of nervous 

 and chemical correlation, animals develop symmetrically 

 and their bodily processes perform their functions har- 

 moniously; they make the necessary adjustments to the 

 environment, both in time of quiet and in time of stress, 

 and carry on the activities essential to racial reproduction. 

 A failure in adjustment means, to th*e individual, impaired 

 efficiency, bodily injury, disease, or death; to the race, 

 failure in perpetuation, which to some extent, no matter 

 how slight, diminishes the breadth of the front which the 

 next or succeeding generations must present to their en- 

 vironment if the race as a whole is to survive. 



