148 Inheritance and Evohition in Ortlioptera I 



though the numbers are small, the 10:3 ratio suggests that the 

 parents were texanus-leuconotus {^AB) heterozygotes, since this is a 

 close approximation to the expectation of 9*75 J5 and AB.Z'I^ A. In 

 cage (6) one of the parents could have been of the constitution AB and 

 the other pure B, or both could have been pure B, because at that time, 

 as has already been noted, in making records no distinction was made 

 between the heterozygous texanus-leuconotus (^J5) and the homo- 

 zygous leuconotus (5). The specimens have been kept preserved in 

 alcohol and although the general outlines of the patterns are still 

 distinct they are not clear enough to permit the fine distinction which 

 would be necessary for selecting the homozygous leuconotus {B) from 

 the heterozygous texanus-leuconotus {^AB), as can be done now with 

 the live specimens. 



It is obvious that nothing further than that they are AB and B can 

 be ascertained concerning the composition of the parents in cages (c) 

 and {d), though the ratio of 194 : 47 in cage (c) is suggestive of the 

 expectation of 180'75 : 60'25, if all four of the individuals had been 

 texanus-leuconotus {AB) heterozygotes. Although the matings were 

 made in such a way as to make the numerical ratios of no value, yet 

 it is to be noted that no unexpected individuals appeared — all were 

 texanus (J.), texanus-leuconotus {AB), or leuconotus {B). 



The i^2 impure forms of the appearance of leucothorax were inbred 

 in the same way as were the F^ impure leuconotus, i.e., essentially as 

 a group culture. As in the case of the homozygous leuconotus and the 

 heterozygous texanus-leuconotus, I was not able to distinguish between 

 the homozygous leucothorax and the heterozygous texanus-leucothorax. 

 Four group matings were made as follows : (a) 1 male x 1 female ; 

 (6) 2 males x 2 females ; (c) 2 males x 2 females, and {d) 2 males x 

 2 females. The F^ results from these matings were as follows : from 

 (a) 259 leucothorax; (6) 65 leucothorax : 11 texanus; (c) 103 leuco- 

 thorax : 15 texanus; and {d) 27 leucothorax : 3 texanus. If none of the 

 leucothorax F^ individuals from (a) had been bred further, it would not 

 be known whether the Fc, parents were both homozygous leucothorax (0), 

 or one of them homozygous (0) and the other heterozygous texanus- 

 leucothorax (-4C), but 2 males X 2 females were bred and gave in F^, 

 after great mortality due to drought in the cage, 9 leucothorax : 2 

 texanus; thus showing one of the parents in cage (a), F^, to have 

 been undoubtedly heterozygous texanus-leucothorax {AG), The in- 

 dividuals from the other cages were not bred further. It is here 

 again obvious that the composition of each of the parents in these 



