No. 683] ON SUBSTRATUM HOMOGENEITY 437 



The wheat field of Mercer and Hall is divided into 

 25 x20 = 500 plots, Map B. Combining the plots by 

 fives from east to west and by fours from north to south, 

 I have condensed this into 5x5 = 25 C P plots, each of 

 20 ultimate plots as shown in Table II. 



Summing the actual yields and the squares of yields 

 for the ultimate plots and the squares for the combination 

 plots, I find the following values : 

 For wheat grain 



S(p) =1974.32, S(p 2 )= 7900.6790, tf = 500, 

 p = 3.949, <r p 2 = .209600, 

 S(C P *) = 156419.3106, m[n(n - 1)] = 25 X 20 X 19 

 = 9,500, 



[S(C P 2 ) =15.633540, 

 which leads to 



15.633540 -(3.949)' 



.209600 -• 186 ±.029. 



For wheat straw 



8(p)=z 3257.40, S(p 2 ) = 21623.9802, N = 500, 

 p= 6.515, a p 2 = . 805341, 

 S(C P * = 427479.9920, w[n(n- 1)] =9500, 

 [S(C P 2 ) - W]/»[n(n-l)] =42.721685, 



