i.] ANTECEDENTS. 37 



the second. It is a matter of great interest to 

 compare with these figures the number of the 

 children of the scientific men themselves. It is 

 easy to do so with fairness, because the time 

 of marriage proves to be nearly the same in 

 both cases ; if anything, the scientific men marry 

 earlier than their parents. It remains to eliminate 

 all cases of absolutely sterile marriages on the 

 part of the scientific men, and those in which 

 there might yet be other children born. Having 

 attended to these precautions, I find the number of 

 their living children (say, of ages between 5 and 30) 

 to be 4*7. This implies a diminution of fertility 

 as compared with that of their own parents, and 

 confirms the common belief in the tendency to an 

 extinction of the families of men who work hard 

 with the brain. On the other hand, I shall show 

 that the health and energy of the scientific men 

 are remarkably high ; it therefore seems strange 

 that there should be a falling off in their offspring. 

 I have tried in many ways to find characteristics 

 common to those scientific men whose families 

 were the smallest, but have only lighted upon 

 one general result, which I give provisionally, 



