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 such 
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. 
