The Developing Period 65 



the association fibres are developed late in the 

 child ; they are likewise the latest acquirements 

 of the race. The lower and more fundamental 

 animal traits are transmitted by inheritance in 

 greater degree than the higher ones. 



In the human being, the brain assumes over- 

 mastering importance in the scheme of evolu- 

 tion, hence its proper growth and development 

 are relatively of much more importance than 

 that of other parts of the body. The extremely 

 rapid evolution of the brain during infancy, 

 and the fact that the future efficiency and well- 

 being of the child depend largely upon its nor- 

 mal and healthy gro^vth renders the study of 

 the infantile head of great interest. As the 

 skull is fairly representative of the brain dur- 

 ing the years of its first development, measure- 

 ments taken during infancy are more instruc- 

 tive as to brain size and evolution than those 

 taken in later years. The skull changes con- 

 siderably in its proportions during the first 

 years of life, and then more slowly up to the 

 end of the seventh year when it has very nearly 

 attained its full size. At birth, the circumfer- 



