THE PARASITIC WASP, HADROBRACON BREVICORXIS. 47 



orange males and in later generations have shown apparently 

 the same range of variability. The numerical deficiency of 

 females as compared with their brothers is in this case probably 

 due to the age of the mutant when mating occurred and a con- 

 sequent scarcity of spermatozoa. 



The mutant was set with four of his orange granddaughters, 

 but only a single female was obtained. The record of offspring 

 is as follows: 



The single orange female from mating 312 was crossed to one 

 of her brothers and produced 35 orange males and 47 orange 

 females. Twenty-five of these orange females, isolated as virgin, 

 produced 2,549 orange males. By back-crossing some of these 

 males to their virgin mothers, orange females were produced 

 and a stock obtained which has since bred true. 



Further crosses involving orange may now be summarized. 



Twenty-nine black females from various homozygous black 

 stocks crossed with various orange males, produced all black, 

 1,369 males and 665 females. 



Two pairs of heterozygous females by black males produced 

 28 black males, 26 orange males, and 39 black females. 



Twenty-six heterozygous females derived from various crosses 

 of black by orange produced only males, 967 black and 996 orange. 



Seven other heterozygous females crossed with orange males 

 produced 170 black males, 151 orange males, 82 black females 

 and 99 orange females. 



Thirty virgin orange females derived from various sources 

 produced 2,996 orange males, no females. 



Twenty-eight orange females set with males produced 3,365 

 orange males, no females. 



Forty-seven orange females, from various sources mated with 

 orange males likewise from various sources, but not from the 

 cross of orange female by black male, produced only orange, 

 2,333 males and 1,002 females. 



