R K. Nabours 149 



cages cannot be ascertained by the appearance of their F^ offspring, 

 because 2 males x 2 females were used in each instance. However, 

 no unexpected types appeared, and we do know that the parents 

 were of the two compositions, C and AC, and no other than these. 

 The results from the inbreeding of these F., impure leucothorax are 

 shown as a group in Table I, F,, and in more detail in diagram 

 1, F,. 



A group culture of 2 males x 2 females was made from the Fo 

 texanus which had come from the ^i impure leuconotus and they 

 gave only texanus in F^ when the culture was terminated. Similarly, 

 a group culture was made of the F„ texanus which had come from the 

 Fi impure leucothorax and they bred true in F^ when they were also 

 destroyed. 



Fi results from the separate inbreeding of the F^ forms of this 

 series. Several of the F-^ leuconotus-leucothorax {BC) were inbi-ed, 

 but on account of poor attention, the mortality of the F^ progeny 

 was very great. The record of those reaching maturity was 10 

 leuconotus : 17 leuconotus-leucothorax : 3 leucothorax (Table I, F^). 



From {d), of the texanus-leuconotus {AB) F^ group culture, two 

 pairs, a pair each in separate cages, of the appearance of leuconotus were 

 bred. After great mortality the F^ result in (o) was 8 leuconotus : 3 

 texanus, and the pair in (h), gave 13 all leuconotus. These results 

 added together are shown in Table I, F^, as a group culture, giving 

 a 21 : 3 ratio. It appears that the parents in cage (a) were texanus- 

 leuconotus (AB) heterozygotes, and that the cage (6) parents were both 

 either homozygous leuconotus {B), or that one of them was homozygous 

 and the other heterozygous texanus-leuconotus {AB). However, when 

 a pair from cage (6) were bred, they gave in F^, 8, all leuconotus in 

 appearance, and this closed the impure leuconotus part of the experi- 

 ment (Table I, F^ and F,). 



From the cage (a) i^s progeny, in the impure leucothorax series of 

 this experiment, two males and two females of the appearance of leuco- 

 thorax were mated as a group culture, and they gave in Fi, 9 leucothorax : 

 3 texanus. This result, though small in numbers, shows quite clearly 

 that the pair of the appearance of leucothorax taken from the (o) F^ 

 culture and bred to make (a) F^ 259 all leucothorax in ajipearance, 

 were not both of them homozygous leucothorax {G), nor were they both 

 heterozygous texanus-leucothorax {AC), but that one of them was a 

 homozygous leucothorax (0), and the other a heterozygous texanus- 

 leucothorax {AC), a matter to which attention is given above. The 



