482 E. ELEANOR CAROTHERS 



be morphologically the same for all individuals. Vomov shows 

 (p. 448, fig. 1, see my text fig. 4) spermatogonial complexes from 

 four individuals. A and B are from the same individual and 

 agree in having eight or nine atelomitic chromosomes. D, from 

 another individual, seems to be of the same type, while C and F 

 from two other individuals, have eleven or twelve. This varia- 

 tion is made conspicuous by the arrangement in his text-figure 

 2 which shows strikingly the difference of the complex of individ- 

 ual C from that of B. However, Voinov states (p. 450) that the 

 form and size are constant for the species. To quote: "Dans 

 les dessins ou les chromosomes des quatre premieres plaques 

 sont groupes suivant leur resemblance (fig. 2), on voit que la 

 forme et la grandeur sont constantes pour l'espece." On the 

 contrary, should one judge by these figures, (see my text-fig. 5) 

 one would conclude that even the number was not constant 

 since D lacks chromosome number 7. Also numbers 7 A and 

 7B which purport to be homologous chromosomes, — drawn 

 even from the same individual, — certainly bear no resemblance 

 in size. This may better be attributed to the fault of the ob- 

 server than to the material, as chromosome 7B would seem from 

 the drawing to be much more homologous with 6A, and one mem- 

 ber of 6B with 7A. 



This evidence, together with the fact that none of his second 

 spermatocyte figures show any indication of the presence of a 

 tetrad [His chromosome 'b' (p. 488 C, see my text fig. 3, 4) looks 

 like any ordinary dyad and not a tetrad], has convinced me that 

 his 'hexad' is a J-shaped tetrad. This would simplify matters, 

 as on Voi'nov's interpretation there are two sex-determining 

 mechanisms present: — an accessory which forms part of the 

 'hexad' and in addition an unequal pair which he believes to 

 be an XY. This leads him to remark (p» 496): "C'est un cas 

 tres rare, comme celui de Banasa calva parmi les Hemipteres, 

 ou de meme, grace a la coexistence de deux chromosomes 

 sexuels, naissent quatre categories de spermatides, distinctes 

 materiellement. ' ' 



In 1905 Wilson reported the presence of an accessory and an 

 idiochromosome pair in Banasa calva, but in 1907 he published 



