GENETICS OF HETEROMORPHIC CHROMOSOMES 



465 



Circotettix verruculatus, then, does not constitute an excep- 

 tion, so far as number of chromosomes is concerned (when the 

 total number of chromatids in the complex is taken into con- 

 sideration), to the typical conditions in the Acrididae. And 

 since the complex is essentially similar in the several species of 

 Circotettix, so far studied, it seems safe to extend this conclusion 

 to the genus. 



d. Differential frequency of the atelomitic condition of the three 

 critical pairs. In order to determine whether the offspring of a 

 particular mating were giving the range of chromosomal varia- 

 tion of the species, or that to be expected from a union of the 

 gametes of their parents, it was necessary to find approximately 

 the normal frequency of any given condition for each member 

 of the three pairs numbered 1, 7, and 8. 



A study of forty wild males showed that tetrad number 1 

 was telomitic in thirty-two individuals, atelomitic in two, and 

 heteromorphic in six — a ratio of 70 telomitic to 10 atelomitic 

 homologues. Tetrad number 8 paralleled this condition closely, 

 since in thirty-three animals it was telomitic, in one atelomitic, 

 and in six heteromorphic, giving the ratio 72 telomitic to 8 

 atelomitic dyads. Tetrad number 7, on the other hand, prac- 

 tically reversed conditions, since in thirty-one animals it was 

 atelomitic, in one telomitic, and in eight hetermorphic — a ratio 

 of 70 atelomitic to 10 telomitic dyads. The situation is sum- 

 marized in table below. 



Comparision of the ratio of the sum of the telomitic to the atelo- 

 mitic dyads of the three pairs which is roughly two to one with 

 that of the individual pairs shows clearly the necessity of dealing 

 with each pair separately. 



