338 ROBERT H. BOWEN. 



heavily impregnated layer being characteristically absent on the 

 side in contact with the nebenkern. In a short time the fusion 

 has progressed so far that only three or four separate elements 

 can be distinguished, and these too, continuing the process of 

 fusion, soon unite to form a single mass of rather regular shape 

 and dimensions (Fig. 21), which constitutes the "sphere" or 

 idiosome of many writers on spermatogenesis. In the final 

 stages of fusion the Golgi elements have tended to collect in the 

 groove between the nuclear membrane and the nebenkern (Fig. 

 20), so that when its formation is completed, the single, con- 

 densed mass is always similarly situated (Fig. 21). 



The dictyosomes distributed to the spermatids during the matu- 

 ration divisions thus fuse to form a real Golgi apparatus, from 

 which the acrosome is to be derived ; and I therefore propose to 

 call it the acroblast. 1 This term was first suggested by King 

 ('07) and was subsequently adopted by Gatenby ('17) for desig- 

 nating in cells of various stages certain bodies supposed to give 

 rise to the acrosome. The nature of these bodies in Miss King's 

 work is doubtful, but in the case of Gatenby the acroblasts are 

 certainly the Golgi bodies. It seems to me a procedure of little 

 practical use and of very doubtful theoretical value to extend the 

 term " acroblast " to structures present in the cell prior to the 

 actual formation of the spermatid. In the first place, as I shall 

 try to bring out later, it is highly probable that the Golgi ap- 

 paratus is always the source of the acrosome, and it is clearly 

 not desirable to use " acroblast " merely as a synonym for Golgi 

 body or Golgi apparatus. Furthermore, cytologists are in actual 

 want for some purely descriptive term which can be universally 

 applied to the anlage of the acrosome without necessarily involv- 

 ing any implications as to origin and homology such as have so 

 beclouded the terms " idiosome " and " sphere." I therefore 

 propose to restrict the term acroblast to that body or bodies 2 

 from which the acrosome is actually derived. 



1 My attention was first called to this very useful term by Professor Wilson. 



2 I use the word "bodies " because there are probably cases in which the 

 acrosome is originally multiple, the parts later fusing into a single body, as 

 for example in Lepidoptera, according to Gatenby ('17). In fact this occa- 

 sionally happens in the Hemiptera, indicating that the small aggregates which 

 finally fuse to form the definitive acroblast are each potentially acroblasts in 

 miniature. 



