;ii MENDEL'S WORK 19 



exclusive so far as the gamete was concerned. It 

 nust be pure for one or the other of such a pair, 

 md this conception of the purity of the .gametes is 

 the most essential part of Mendel's theory. 



We may now proceed with the help of the 

 iccompanying scheme (Fig. i) to deduce the re- 

 sults that should 

 flow from Mendel's 

 conception of the gameteS( 

 nature of the gam- 

 etes, and to see 

 how far they are 

 in accordance with 

 the facts. Since 

 the original tall 



plant belonged to "*" -D < " 

 a strain which bred & Q ^ (^ ^ & 



true, all the gam- 



^~\ f \ "* 



etes produced by it O *- (^J <-- 



must bear the tall F 2 



generation 



character. Simi- 



11 11 ^1 FIG. i. 



larly all the gram- 



Scheme of inheritance in the cross of tall with dwarf 



eteS Of the Original P ea - Gametes represented by small and zygotes 



by larger circles. 



dwarf plant must 



bear the dwarf character. A cross between these 

 two means the union of a gamete containing 

 tallness with one bearing dwarfness. Owing 

 to the completely dominant nature of the tall 

 character, such a plant is in appearance indis- 

 tinguishable from the pure tall, but it differs 

 markedly from it in the nature of the gametes to 

 which it gives rise. When the formation of the 

 gametes occurs, the elements representing dwarfness 



