BIOMETRICS 151 



(the dark rays on top of the seed-capsule) in three groups 

 of poppies in Nos. I. and II. for two wild poppies, in 

 No. III. for a greater number of poppies forming a local 

 race. The numbers of stigmatic bands are indicated on 

 the base line. We have the following modes and means of 

 the three curves respectively : 



Mode. Mean. 



No. 1 8 .. 8-50 



II ii 1075 



III 10 . . 9-84 



We see that the race has a mode different from either of 

 the individual poppies, and also a different mean. 



In a symmetrical curve and we shall in the following 

 deal only with symmetrical curves the mode and mean 

 fall together : in curve III. this is nearly so, there being a 

 very slight difference between the mode and the mean. 



Q Q 



F IGt 69. CURVES OF PROBABILITY. (After Lotsy.) 



But all this is not yet sufficient. What we want is to be 

 able to compare the variability of one set of varying 

 characters with another set. In other words, we have to 



