DEGENE KATE (APYRENE) SPERM-FORMATION OE MOTHS. 467 
Meves worked upon Pygaera bucephala, and has 
given a correct account of every stage, except that he has 
failed to note the behaviour of mitochondria in spireme 
formation, of the acrosome and of the centrosome. These 
important stages are considered in the present paper, and the 
material used has proved more favourable than Pygaera. 
In the Metazoa most of the latest work has shown that the 
spermatid about to become a spermatozoon contains the 
following bodies : Nucleus, centrosome (or centrosomes), 
mitochondria, acroblast, and one or two basophil or siderophil 
bodies besides. The latter, which might have some special 
significance, are not dealt with here. 
The special purpose of this paper is to attempt to analyse 
the inter-relationship of the first four bodies in the spermatid. 
We know that in spermiogenesis, and by this term I mean 
the stages from spermatid onwards, the nucleus, centrosome, 
acroblast, and mitochondria undergo a number of definite 
movements and changes which finally culminate in the pro- 
duction of that remarkable cell, the spermatozoon. In 
moths, and may be in many other forms, degenerate stages 
of spermatogenesis occur, and it has been by observing these 
stages in the former that I have attempted to come to 
some conclusion concerning the various functions and the 
various influences which together go to produce the sperm. 
If, in some cases, my conclusions be not clear, it is because I 
haye found great difficulty in identifying the special cell 
element which might be a centre of influence for another 
cell body, but it will be seen that the evidence provided 
permits one to make tentative statements. 
The technique employed was similar to that used in my 
previous paper (4). Smerinthus populi and Pieris 
brassicae were most satisfactory forms upon which to work; 
in addition Pygaera bucephala and Portliesia similis. 
were examined. The character of the apyrene or degenerate 
sperm-formation was . found to be somewhat different in 
different species. Thus in my Pierid material almost, if not 
invariably, degeneration, or the occurrences leading to the 
