No. 583] ON SUBSTRATUM HOMOGENEITY 451 



For grain, r HP2 = .472 + .035, 



For nitrogen, r PlP , = .096 + .045, 



as compared with the following values for a 2 X 2-fold 

 grouping 



For grain, r PlP2 = .603 ± .029, 



For nitrogen, r PlP2 = .115 ± .044. 



Finally consider the constam 

 yields published by lloltermark ; 



For a 2 X 2-fold grouping, 

 For a 2 X 4-fold grouping, 

 For a 2 X 8-fold grouping, 



nluced from the bay 

 ^arsen. 



= .609 + .027, 

 = .471 ± .034, 

 = .278 + .040. 



Thus for every species of plant and every character con- 

 sidered the correlation between associated ultimate plots 

 decreases as the number of plots grouped increases. 20 



285.2 



