DEGENERATE (APYKENE) SPERM-FORMATION OF MOTHS. 481 
authors have already pointed out that it has not satisfactorily 
been shown that the “ apyrene ” is able to enter the egg. 
The view taken in this paper is that the atypic sperm, in 
moths at least, has no special significance beyond the fact 
that it originates from a state of degeneration. I have shown 
in the figures in this article that almost every conceivable 
stage in degeneration from spermatocyte- onwards can be 
found in lepidopterous spermatogenesis, and even if there 
appears to be a special, true “ apyrene ” sperm, which I 
doubt, this is because it is at one special stage that degenera- 
tion is most prone to appear. I have already pointed out (4) 
that degeneration cannot be due to a starved condition of the 
larval or pupal moth or butterfly, but exactly why degenera- 
tion should appear at all I cannot say. Nevertheless I 
consider it certain that the appearance of “ apyrene and 
oligopyrene ” spermatozoa is directly traceable to the same 
forces which cause a whole nest of primary or secondary 
spermatogonia to undergo degeneration. Even if subsequent 
research should show that fertilisation by an atypic sperm is 
possible, this cannot show that the latter has a special sig- 
nificance from the sex point of view, though it would intro- 
duce an element of very strong probability. I have already 
remarked, in the section dealing with the nucleus, that a 
sperm might be overtaken by degeneration after it had 
entered the egg. This matter will easily be settled by a 
cytological examination of enough fertilisation stages, together 
with a comparison between the expected and the true sex 
ratios in breeding experiments. 
The “Apyrene” Spermatozoon of the Moths and 
of the Molluscs. 
Among later workers on the atypical spermatogenesis of 
Mollusca there is a clear consensus of opinion that the 
“apyrene” sperm could not fertilise the egg, and this seems 
completely substantiated by Reinke's (1) inability to find any- 
thing but eupyrenes in the receptaculum seminis of Strombus. 
Goldschmidt (7) advances the view that the “ apyrene ” 
