236 PHYSICAL BASIS OF CIVILIZATION 



of movements, require greater varieties and greater 

 numbers of cortical centres to initiate movements, 

 and a greater number of white nerves to transmit 

 the impulses; therefore, larger masses of brains. 



With reference to the third kind of exceptions, 

 when certain types display greater energy, then 

 the brain tissues have more to attend to and must, 

 therefore, be more massive, or there must be more 

 of them. Such creatures must, therefore, center is 

 paribus, have larger brains. 



Since exceptions to the rule are thus traceable 

 to these three causes, therefore do they confirm and 

 corroborate the rule. 



Professor John Marshall has, however, reported 

 that post-mortem examinations on the brain 

 weights of distinguished scientists, statesmen, his- 

 torians, authors, etc., show variations from 45.4 to 

 64.7 ounces. The last weight is about \ above, 

 the first about T V below, the reported average brain 

 weight of adult civilized Europeans. Professor Karl 

 Pier son and Dr. Raymond Pearl have reported the 

 result of post mortem examinations on the brains 

 of 2100 men and 1034 women, taken from different 

 European nationalities, and from these the conclus- 

 ion is drawn, that ''there is no evidence that brain 

 weight is sensibly correlated with intellectual abil- 

 ity. " Although these observations were not made 

 on either primitive man, nor on the creatures below 

 him — although the phrase "intellectual ability" 

 seems inapplicable to either of these, yet since some 



