R. K. Nabours 



155 



(3) The interbreeding of heterozijgotes. 



Experiment III. All the crosses of heterozygous individuals with 

 homozj'gous ones and the inbreeding of heterozygous ones had given 

 results that could hardly be interpreted in any other way than by 

 assuming that the heterozygous, or hybrid, individuals gave gametes 

 alternatively, one representing the male j)arent and the other the 

 female parent. Not a single exception to this rule had been noted. 

 A few crosses had been made between different heterozygotes from 

 nature whose constitutions were not ascertained till their Fi and F.^ 

 progeny gave the clue (Exp. I, Table I, and Exp. II (a), (6), (c), 

 Table II (a), (6), (c)). At this time it seemed that some crosses 

 ought to be made between ditfereut hybrids of known constitutions ; 

 so the following crosses were made simultaneously : 



((f) A leucothorax-luteolineatus {CE) male from Exp. II (c), F^ 

 (Table II (c), -fj) and a leuconotus-leucothorax {BC) female from 

 Exp. Ill (c), Fi (Table IV (e), F^) were crossed, and they gave in the 

 F^ generation {F„ Table III («)): 



/', 



(c) 



(e) 



B = leticonotus. C = leucothorax. E=luteolii>,e<-itug. 



F = rii/ruluieiittis. I = iiigronoOxtus. 



