J. BttoNTti GATENBY. 
472 
has not yet been carrier! out far enough to allow me to attack 
with any complete surety the view that the acrosome is derived 
either partly or wholly from the sphere or archoplasm, but I 
confess that 1 consider this suggestion improbable; not only 
because I cannot allow that the observers who espouse this 
view have shown clearly that such is the case, but also because 
the fixatives most favourable, or at least favourable enough to 
demonstrate archoplasm, at the same time uniformly unfavour- 
able to acroblastic material. One result of this study of the 
atypical spermatozoon has been the confirmation of a sugges- 
tion advanced by me in a previous paper ( 4 ), that the acroblasts 
in later stages are influenced by the nuclear matter alone. 
Figures have already been given to show that in the 
maturation divisions the acroblasts of Lepidoptera are 
orientated in a remarkable and special manner in relation 
to the chromatin, and it has been shown that this relation- 
ship is rarely departed from ; a review of some of the best 
work on the plasmatic structures in other orders leads me to 
conclude that, just as in moths and butterflies, the acrosomic 
material is definitely and undoubtedly subservient to the 
nucleus at almost all stages. The acroblast (or acroblasts) is 
almost always found to lie in the cytoplasm in the neighbour- 
hood of the nucleus, and sooner or later takes up its position 
upon the surface of the latter. Now, a very important ques- 
tion to solve was whether this special orientation of the acro- 
blast upon the surface of the nucleus could be brought about 
by the instrumentality of any body other than the latter. 
Meves, in his work on the “ apyrene ” spermatozoa of moths, 
completely overlooked the acroblasts, and my own work on 
the same species as he used leads me to believe that Pygasra 
bucephala 1 is not good material for this study. Pierids and 
Smerinthids are very favourable. It is known that in the so- 
called “ apyrene” or atypic spermatozoon the nuclear matter 
fails to act normally and gradually becomes carried down 
1 I have since ascertained that in P. bucephala the acroblasts are 
difficult to discover because they so closely resemble mitochondria in 
size and shape. 
