701 



. THE AMERICAN NATURALIST 



[Vol. XLVI 



When L t is absent, however, and L 2 is present the zygote 

 exhibits the same general degree of fecundity (under 30) 

 which it would if L 1 were present alone. These two inde- 

 pendent factors L 1 and L 2 must be present together to 

 cause high fecundity, either of them alone, whether 

 present in one or two " doses," causing the same degree 

 of low fecundity. 



5. The second physiological factor L 2 behaves as a 

 sex-limited (sex-correlated or sex-linked) character, in 

 gametogenesis, according to the following rule: The 

 factor L 2 is never borne in any gamete which also carries 

 F. That is to say, all females which bear L 2 are hetero- 

 zygous with reference to it. Any female may be either 

 homozygous or heterozygous with respect to L x . Any 

 male may be either homozygous or heterozygous with 

 reference to either L,. L 2 or both. 



FLxh 



) reason that gametes of t 



