PRIMATES 481 



which suggests that his first home was in a warm chmate, but 

 for which it is difficult to conceive a function. There are, however, 

 some signs of a tendency to lose hair in various monkeys, where 

 use is made of bare coloured areas for sexual display. The chief 

 peculiarity in man's soft parts is the size of his brain, and 

 especially the great development and convolution of the cerebral 

 hemispheres. With this goes his great mental development, 

 in which he differs so much from all other animals as to give some 

 justification for the opinion of his own uniqueness which he has 

 long held. Young chimpanzees are at least the mental equals of 



Fig. 371. — A dorsal view of the pancreas and duodenum of man, with the 

 pancreatic duct exposed, showing its junction with the bile duct, and the 

 accessory pancreatic duct. — From Cunningham. 



I, Pancreatic duct ; 2. superior (anterior) mesenteric artery ; 3, superior mesenteric vein (branch of portal 

 vein) ; 4, ' head ' of pancreas ; 6, bile duct ; 7, accessory pancreatic duct or duct of Santorini, com- 

 municating both with duodenum and with main pancreatic duct ; 8, first (superior) part of duodenum. 



children for the first year or two, but they soon cease developing 

 and never progress beyond, at the most, the level of an average 

 child of two or three. In language they are greatly inferior even 

 to such a child. Much is sometimes made of the ability of man to 

 think in terms of words and abstract concepts, but although 

 this is common in the writers of books, it is by no means universal ; 

 even many books are, hke abstract painting and the song of 

 birds, expressions rather of an emotional state than of precise 

 thought. The abihty to reason, that is to foretell the probable 

 consequences of actions which have not been carried out before, 

 is presumably found in all normal men, but it is not always 

 used. Anatomical differences are : in man the pancreatic 

 duct joins the bile duct near the entry of the latter into the 

 duodenum (Fig. 371) ; the vermiform appendix is a good deal 



