DEGEN Eli AT K (APYRENE) SPERM -FORMAT I ON OF MOTHS. 475 
The nucleus lacked the requisite force to place itself at the 
head of the sperm, but retained its relationship to the acro- 
blasts, which fused, secreted the acrosome, and gave rise to a 
normal structure. But that missing power, whatever it may 
be, still was wanting in the nucleus, and evinced itself by 
causing a lagging in the proper formation of the elongate 
sperm nucleus. This lagging, be it marked, did not affect 
the acrosome, which became normally formed, and so the 
condition in PI. 26, fig. 9, was reached. In PL 26, fig. 13, 
each of the four nuclei is attended by a small round granule 
( (jr . ) , which is probably an acrosome, but in the cell normal 
acroblasts (A.) were still present. In PI. 26, fig. 12, the 
nucleus had a granule applied upon its surface ( G .). It is 
probable that if this body arises from an acroblast it is 
abnormal, for I have not found like stages in normal nests ; 
in normal stages such a granule would be surrounded by semi- 
lunar acroblastic ring (see figures in previous paper). The 
question of the attachment of rhe acrosome upon the nucleus 
may now be dealt with ; in the snail I find that the acrosome 
is embedded in the nucleus in a wedge-like manner. In some 
other forms, as, for instance, in the rat (after Duesberg (5)), 
the acrosome is plastered upon one side of the nucleus. In 
some other Mammalia the acrosome seems to be fixed straight 
across the square head of the nucleus. In fact, almost every 
conceivable manner of joining between these two elements 
can be found. 
My study of Lepidopterous spermatozoa, leads me to 
believe that the acrosome is sensitive to some influence 
which orientates it. PI. 26, fig. 9, shows that each 
acrosome, though it has no normal nucleus to fix upon, is 
sensibly orientated towards the sertoli-cell or upper end of 
the sperm-nest. It is quite probable that the front end 
of this acrosome in Pi. 26, fig. 9, represents what would be 
the front end of the acrosome in the normal sperm. Now 
the acrosomes in Pi. 26, fig. 9, are not all resting upon the 
nucleus, and the same applies to PI. 26, fig. 15, in which 
the arrow denotes the head or front end of the nest. In 
