OBSERVATIONS AND DEDUCTIONS 25 



X X X X 



Y y Y y 



9:3:3:1 



and so on. 



(9) Each character in which the parents differ is carried 

 by half the groups in their hybrids' progeny precisely. 

 For instance, two of the four groups in the last section 

 carry X, two carry Y, two carry x, and two carry y. 



(10) If more than half the groups in a set of hybrids' 

 progeny carry any character, then that character is 

 carried by all the other groups in the set, for, if it were 

 not, then the groups would differ from each other in 

 more characters than is consistent with the size of the 

 set. If, for instance, the third group in the following 

 two-pair set did not carry Z, it would differ from the 

 first and last groups in more than one pair and from 

 the other middle group in more than two : 



(11) If one or more groups in a set carry a character 

 outside those concerned in the production of the set, 

 then that character is common to all the groups in the 

 set. If, for instance, the first group in the following 

 two-pair set carried Z, then, unless they also carried Z, 

 the middle groups would differ from the first in more 

 than one pair of characters, thus : 



9 XYZ 



3 Xy 



3 xY 



1 xy 



