152 The Third and Fourth Generation 



It is one of nature's potent methods for the 

 improvement of all living things, the elimina- 

 tion of the unfit, the reproduction of the fit. 



Any farmer would promptly predict the 

 fate of a herd of cattle in which the scrub stock 

 was allowed to breed faster than the pedigreed 

 stock. Yet there is no doubt that in civilized 

 y countries large families are the rule among the 

 undesirable elements and the exception in the 

 best stock. Pierson carefully prepared a tabu- 

 lation showing the relative fertility of various 

 stocks. The mentally defective, criminal, deaf, 

 mute, and degenerate stocks head the list with 

 average families of from five to seven children, 

 while the families of the college-bred pro- 

 fessional men average less than two. Cattell 

 gathered data for 917 American men conspicu- 

 ous in scientific achievement and found they 

 averaged 2.22 children per family, while the 

 average number of children in the families of 

 the parents of these men was 4 . 66, a decline in 

 the birth-rate in this evidently superior stock 

 of more than one-half in one generation.' 



' Scientific Monthly, IV (1917), 252. 



