EVOLUTION 



395 



found on the same plant with capsules of 9 bands in the 

 I 1,026 capsules included in the table. At the bottom of 

 each column is given the mean number of bands for that 

 column, and the mean of the whole series is 10.04. Thus 

 the mean of the 9 column is not 9 but 9.51 ; in other 

 words, the capsules associated on the same plant with 

 a 9 capsule have not a mean of 9, nor the general 

 population mean of 10.04, t)ut regress from 9 towards 

 the general mean. The row of means shows that this 

 rule is universal ; the mean of the associated capsules tends 

 to the general mean. The following diagram illustrates 

 this result graphically. Along the horizontal line we have 

 scaled the number of stigmatic bands on the selected 

 capsule, along the vertical lines are plotted lengths 5«, 6/;, 



Number of Stigmatic Bands on Selected Capsule. 



5 6 7 8 9 W 71 iZ J3 /^ /5 J6 



6 



U 



s 



3 



JO 



// 



5 I'i 



JS 



J5 



m 



Regression Line for Poppy Capsules. 



Fig. 28. 



7r, 8(^, etc., equal to the successive means 6r:,i, /.ir, 

 8.22, 9.06, etc., of the associated group of capsules. The 



