48 



When Retzius made his observations there is no reason to 

 doubt that he was right in the main, but there is sufficient 

 evidence in these tracings to show that the exceptions are 

 so numerous as to render a classification founded on suclj 

 principles valueless. 



One other point is of interest. Progressive development 

 always means greater integration and greater differentiation. 

 The brain of the primates becomes constantly more un- 

 symmetrical as it becomes larger. In the bosjesman, as 

 in the chimpanzee, the convolutions are comparatively 

 simple and symmetrical. It is, to say the least of it, not 

 improbable, that the increasing cerebral asymmetry will 

 produce some effect upon the bony cranium, and hence it 

 is not fanciful to look upon this bilateral asymmetry as 

 evidence of a higher type than would be afforded by a per- 

 fectly symmetrical skull. 



