A Still Progressive Tissue. 141 



The same is true, or true in large part, of every other 

 tissue of the body, save the encephalon. The brain is still 

 forced to develop and grow larger in response to con- 

 stantly changing conditions incident to the world's growth 

 in knowledge. Certain tribes, races and peoples, it is 

 true, adhere to habits and modes of life largely unpro- 

 gressive, and, as a result, show little brain change from 

 generation to generation. It is not so, however, with the 

 westward-moving peoples of the dominant races, — the 

 nations who think and invent. Science is the agent of 

 brain growth. To think, in the true sense of the word, 

 signifies brain development. New inventions stand for 

 cerebral evolution. The changed sensory experiences, 

 too, which result from new inventions, tend to alter the 

 protoplasmic arrangement of the brain, and add to its 

 capacity for growth. In America, to-day, we see heads of 

 varying sizes and shapes, not only the types emigrant 

 from Europe, Asia, and Africa, but types and sizes un- 

 known before in any country. There is actual brain 

 growth among us. A new variety of intellect is being 

 developed. 



A comparison of the earliest human skulls, found in an- 

 cient caves, tombs, and mounds, with those of individuals 

 of the present age, shows that on the whole there has been 

 growth of brain as well as a perceptible alteration in shape 

 in favor of greater intellectuality. Brain has grown greatly 

 in size and improved in form during the last eight or ten 



