10 ROBERT H. BOWEN 
which I have described in Brochymena, and already outlined in 
part by Shaffer (17) in Passalus, and Holmgren (’02) in Silpha. 
The chromophilic substance (Bowen, ’22b) seems to form a 
plate-work very like that in the Hemiptera, and I can find no 
trace whatever of a ‘spireme’ such as Gatenby (718) claims to 
have demonstrated in Tenebrio. At all events, in the later 
stages of condensation, the chromophilic substance is arranged 
exactly as in the pentatomids, and cross-sections of the neben- 
kern (figs. 32 and 33A and B) could hardly be distinguished 
from similar sections of Brochymena. (Compare Bowen, ’22 b, 
figs. 21A and B, also fig. 13.) In one respect, however, there is 
a fundamental difference in the behavior of the nebenkern. In 
the Hemiptera the chromophilic substance disappears completely 
and the nebenkern is-divided into two parts during the initial 
stage in its drawing out; while in the Coleoptera the drawing out 
of the nebenkern has progressed much farther before these same 
results are attained. Thus, in figure 34, a stage in the final con- 
densation of the chromophilic substance is shown, which is quite 
comparable to my figure 16 (Bowen, ’22b) of Brochymena; 
while in an adjacent spermatid (fig. 35) the chromophilic sub- 
stance has completely (?) disappeared. 
In the paper already referred to, I attempted to show that the 
division of the nebenkern always waits on the final disappearance 
of the chromophilic substance. The observations of Holmgren 
on Silpha indicated that this was the case in the beetles, but 
Shaffer’s account of Passalus left the point somewhat in doubt. 
I have, therefore, reexamined this point more carefully in Lixus, 
and I find the facts exactly as described by me in the Hemiptera. 
Cross-sections of the nebenkern through the chromophilic sub- 
stance and also above and below it demonstrate conclusively 
that the nebenkern is divided only in the region from which the 
chromophilic substance has been withdrawn (figs. 833A and 
B, cross-sections of the nebenkern at a stage approximately like 
fig. 34. Compare these cross-sections with figs. 214 and B from 
Brochymena, Bowen, ’22b). 
The halves of the nebenkern ultimately spin out to form the 
tail sheaths so characteristic of insect sperms, and I can find no 
