BASIS OF INVESTIGATION. 65 



no descendants at all, and of those who did very many had sons who 

 fell far below their fathers in the functional capacity of their brains. 



DEDUCTION FROM WEISMANN^S THEORY. 



From the standpoint that all variations arise fortuitously in the 

 germ plasm, we have the deduction that if this be so, then variations 

 occur according to the law of probabilities, and a class which is 

 inferior in mental capacity will remain inferior, while a class which 

 is superior will remain superior. With this we have the fact that 

 what we know as the inferior class is, and has for a long time been, 

 reproducing itself more rapidly than the superior class. From these 

 two elements there is but one deduction, and that is that the race 

 has been deteriorating for several centuries, and that the mental 

 capacity of the men living today is less than that of the men who 

 lived one, two, or three centuries ago. 



THE RECORD OF HISTORY. 



But this deduction is directly and flatly contradicted by history. 

 The record of the nineteenth century shows that the mental achieve- 

 ments of its men were greater than those of all other centuries com- 

 bined. The record of the eighteenth century shows that its men 

 were greater than those of its predecessors and only second to those 

 of the nineteenth century. "Professor Broca found that skulls from 

 graves in Paris of the nineteenth century were larger than those 

 from the vaults of the twelfth century, in the proportion of 1,484 to 

 i,426.' 51 This is an increase in brain size of more than four per 

 cent and indicates a very much larger increase in mental power. 



From a premise containing two elements, we have a deduction 

 which is proved to be false, hence at least one of these elements 



(i) Descent of Man, p. 140. 



