STRUCTURAL CULMINATION 991 



infant, quite as helpless to care for itself and most imperfectly developed 

 even in its simple motor activities. Here, apparently, in one of the higher 

 anthropoids, was demonstrated that tendency to retard functional differen- 

 tiation, in order to obtain the advantages of a long period for maturing. 

 That this great anthropoid shows a period of latency in development almost 

 as long as the human infant is most significant. The phylogenesis of the pineal 

 gland lends weight to the theor\- that it may and does become specialized as 

 a glandular structure, contributing its secretion to the blood stream. That 

 it acts in the capacity of holding in abeyance the de\elopment of statural 

 and sexual differentiation is still somewhat in the conjectural stage. This 

 theory- is advanced with all the hesitation that should naturally attach to a 

 h^-pothesis still but imperfectly substantiated and not having as yet 

 attained universal acceptance. 



SL-MMARY 



A survey of all these facts concerning the primates amply justifies the 

 presumption that this group of animals presents a constancy in brain 

 development b}- which they may be distinguished from all others. E\en more 

 significant are the progressive modifications affecting the fundamental 

 design of the primate brain. Nor can there be any doubt that throughout the 

 entire process of this increasing complexity, the structural pattern of the 

 brain has shown its progressive modifications in harmony with progressive 

 adaptations in the behavior of the primates. Many long periods of structural 

 design, many protracted eras of behavioral trials preceded the final produc- 

 tion of a brain capable of all the powers which distinguish man. 



