SEGREGATION AND DOMINANCE 131 



any way disturbing the identity of the separate 

 blossoms. 



The general formula of segregation that covers 

 all cases of organisms cross-bred with respect to a 

 single character, that is, monohybrids, is given in 

 Figure 43. 



DD 2 D(R) RR 



2 D(R) 



DD DD DD *D(R) RR RR RR 



FIG. 43. General Mendelian formula for a monohybrid. 

 7. HOMOZYGOTES AND HETEROZYGOTES 



A character which is present in the offspring iij 

 double quantity because it was present in both parents 

 is said by Bateson to be homozygous, while an or- 

 ganism which is homozygous with respect to any 

 character is called a homozygote so far as that particu- 

 lar character is concerned. 



In contrast to the homozygous condition, an organ- 

 ism is said to be heterozygous when it derives the 

 determiner of a character from one parent only. 

 Such an organism is described as a heterozygote with 

 respect to the character in question. A homozygous 

 and a heterozygous dominant may appear alike, 



