MENDELISM 



99 



Mendel termed the character, which became apparent 

 in such a hybrid, in this case tallness, the dominant, 

 and the latent character which receded from view, in 

 this instance dwarfness, the recessive. 



The members of such a Mendelian pair are termed 

 allelomorphs. 



When now the hybrids, T(t), were crossed together, 

 the result algebraically expressed was as follows: 



T + t (all possible egg characters) 

 T -j- t (all possible sperm characters) 



TT + Tt 



Tt + tt 



TT + 2T(t) + tt 



That is, one of the four possible cases was dwarf, 1 1, 

 in character and the other three were apparently tall, 

 although only one out of 

 the three was pure tall, 

 TT, while the remaining 

 two were tall with the 

 dwarf character latent, 

 T(t). 



The same thing may be 

 expressed more graph- 

 ically by the checkerboard 

 plan, which Punnett sug- 

 gested (Fig. 16). Each 



FIG. 16. Diagram to illustrate 

 theoretically the formation of 

 the four possible zygotes in 

 the second filial generation of 

 a monohybrid. 



square of the checker- 

 board represents a zygote 



which, having received a gamete from each of the two 

 parents, may develop into a possible offspring. The 

 character of the gametes of the parents is shown out- 



