190 KATHARINE FOOT AND E. C. STROBELL. 



of Hemiptera, but in this preliminary note we shall confine 

 ourselves to discussing the cross between Euschistus variolarius 

 female and Euschistus servus male. From this cross we were 

 able to raise to maturity n males and 16 females of the FI 

 generation and these fortunately mated readily and proved to 

 be very fertile. Seven of these pairs were isolated and the off- 

 spring of each pair raised in separate cages in many cases even 

 the bugs from a single batch of eggs being isolated during the 

 entire period of their development. From these seven pairs of 

 the FI hybrids we raised 249 females and 204 males. These bugs 

 were kept in the laboratory until several days after they had 

 reached the winged stage, when the females were preserved as 

 pinned specimens and 191 of the males were preserved in glycerine, 

 as shown in photos 2 1 to 6. 



An analysis of the maturation divisions would seem to support 

 Castle's suggestion that the Y chromosome may be the bearer of 

 exclusively male characters, for this chromosome is the only 

 one that can be in both the so-called male-producing spermatozoa 

 of each quartette of spermatids resulting from the two maturation 

 divisions, assuming that these divisions occur as illustrated in the 

 text-figure. 



It would seem quite logical to conclude that if a character 

 associated exclusively with the male sex can be inherited from 

 the father, the factors which produce it should be in the so-called 

 male-producing spermatozoon and if they are to be located in a 

 given chromosome it must be the one and only chromosome that 

 ex hypothese can be present in all the so-called male producing 

 spermatozoa, otherwise the character would not be a constant 

 feature. 



If Castle's suggestion is correct, then all characters exclusively 

 male can be inherited only through the father, as the Y chromo- 

 some is never in the female. If then Euschistus variolarius is 

 fertilized by Euschistus servus a form which lacks the spot- 

 none of the offspring should have it, neither the FI nor the Fa 



1 We have photographs of all the male hybrids, but they must be reproduced by 

 the bromide print method in order to secure an accurate reproduction of the shades 

 of difference in the size and intensity of the spot. We hope to be able to reproduce 

 all these photographs when we publish the detailed account of the crossing of the 

 three species, Euschistus variolarius, Euschistus servus and Euschistus ictericus. 



