98 GENETICS 



crossed with each other, they will produce a mixefl 

 progeny, 25 per cent of which will be like the dominanB 

 grandparent, 25 per cent like the other grandparenl 

 and 50 per cent like the parents resembling the doi 

 nant grandparent. 



An illustration will serve to make plain the manm 

 in which this law works out. 



Mendel found that when peas of a tall varietj 

 were artificially crossed with those of a dwarf variety 

 all the resulting offspring were tall like the first parenj 

 It made no difference which parent was selected as tl 

 tall one. The result was the same in either cas 

 showing that the character of tallness is independei 

 of the character of sex. 



When these tall cross-bred offspring were subsj 

 quently crossed with each other, or allowed to p 

 duce offspring by self-fertilization which amounts 

 the same thing, 787 plants of the tall variety and 277? 

 of the dwarf kind were obtained, making approximated 

 the proportion of 3 to 1. 



On further breeding the dwarf peas thus derivdH 

 proved to be pure, producing only dwarf peas, whih* 

 the tall ones were of two kinds, one third of thai 

 "pure," breeding true like their tall grandparent, and 

 two thirds of them "hybrid," giving in turn the PWJ 

 portion of three tall to one dwarf like their pareiM 



These crosses may be expressed as follows : 



Tall, T, X dwarf, t, = tall, T(t). 



That is, tallness crossed with dwarfness equals tallness 

 with the dwarf character present but latent. 



