352 ROBERT H. BOWEN. 



appears to take no further part in the formation of the sperm, 

 while the acrosome is applied to the anterior part of the sperm 

 head and may there undergo further changes the nature of which 

 is of no interest in this connection. 



To draw a general conclusion from the facts in the pentatomids 

 alone might well seem an unwarranted procedure ; but fortu- 

 nately more or less fragmentary accounts from several other 

 animal groups are now available, and they corroborate fully the 

 general outline which I have given. The best case is that of the 

 opossum where Duesberg ('20) has described the origin of a 

 vesicular acrosome with an enclosed granule from the Golgi ap- 

 paratus which he proved to be directly derived from the " iclio- 

 some " of the spermatocytes. Once the acrosome is formed, the 

 Golgi remnant is cast off. A similar though less complete ac- 

 count has been given by Sjoevall ('06) for the guinea pig. From 

 Terni's ('14) figures of Geotriton it seems certain that much 

 the same thing occurs in that amphibian. Further, the work of 

 Schitz ('16) and Gatenby ('190) clearly proves the same thing 

 in several molluscs, though in this case the acrosome is in the 

 form of a granule the exact homologies of which are as yet un- 

 certain. Gatenby ('17) has also described the origin of the acro- 

 some from Golgi bodies (his acroblasts) in the Lepidoptera, 

 though the case is in some respects contradictory and not yet en- 

 tirely clear. Lastly, Hirschler ('13) has described the partial 

 elimination of the Golgi apparatus from the sperm of Ascaris, 

 the remainder apparently forming a body which some writers 

 have compared with the acrosome of typical nematosperms. The 

 failure of many workers to trace the origin of the acroblast is 

 obviously due to the difficulty of demonstrating the Golgi ap- 

 paratus during cell division, and the fantastic descriptions espe- 

 cially among the insects are clearly the result of inadequate fixing 

 and staining methods. From a study of a wide variety of tech- 

 nical methods I can testify to the great differences which are 

 attributable to methods of preparation alone. 



Drawing together these many threads of evidence, both from 

 observation and inference, it seems to me that the following con- 

 clusion embodies a conception of the acrosome which is in ac- 

 cord with all the facts and which establishes its formation as an 



