24 A MANUAL OF MENDELISM 



(5) When pure parents are mated the hybrids carry 

 all the dominants borne by the parents. This holds 

 whether the dominants are all carried by one parent or 

 distributed between the two. For instance XY mated 

 with xy gives the same kind of hybrid as Xy mated 

 with xY. 



(6) In a set of hybrids' progeny, the numerically 

 largest group carries all the dominants, the next sized 

 groups carry each one less, the next sized again two less, 

 and so on down to the smallest group, which carries all 

 the recessives. This will be seen by examining the 

 following two-pair and three-pair sets : 



and 



27 : 9 : 9 : 3 : 9 : 3 : 3 : 1 



(7) In a two-pair set of four groups, the first differs 

 from the next two groups each in one pair of characters 

 and from the last in two pairs, while the middle groups 

 differ from each other in two pairs and from the last in 

 one pair. Similar relations exist among the groups in 

 larger sets. 



(8) If the pairs in which the parents differ are clearly 

 defined at the hybrid generation as regards dominance 

 and recessiveness, the hybrids' progeny can be predicted 

 in number and kind, for the dominants and recessives 

 are distributed according to the scheme 



