Social Environment and Eugenics 93 



that appears will become evident in spite of 

 chance errors of inclusion or exclusion and 

 never because of them; just as any marked 

 contrast between the two lots of selected grain 

 will never be the result of random handfuls 

 that may have been thrown in. The principle 

 is of the greatest importance in estimating the 

 value of such work as that of correlation, 

 which in fact rests on the mathematical regu- 

 larity of the operation of chance. 



It has therefore been concluded that for the 

 purpose at hand the well-known Who's Who in 

 America^ furnishes suitable material. At the 

 ©utset some investigation of the method em- 

 ployed in compiling this work was made, but 

 a discussion of the subject is rendered unneces- 

 sary by the use of collateral sources which, 

 though less comprehensive, are more authori- 

 tative. After the problem was worked out on 

 the basis of the volume just mentioned, re- 

 course was next had to Who's Who in Science,^ 

 a standard work likely to meet acceptance, since 

 the task of picking out leaders from a specific 

 field is easier than from a general field. Lastly, 



1 Who's Who in America, Vol. vii, 1912-1913. A. N. 

 Marquis & Co., Chicago, 1912. 



2 Who's Who in Science. The Macmillan Co., New 

 York, 1912. 



