35O ROBERT H. BOWEN. 



accessory chromosome, an acroblast, new formations in the cyto- 

 plasm, an idiosome of doubtful ancestry, and the Golgi apparatus. 

 In the vertebrates especially, where there is a very definite 

 " sphere " or idiosome in the spermatocytes, the similar formation 

 in the spermatid has been referred to the spermatocyte structures 

 generally without any adequate reasons. It is among the in- 

 sects, where a spermatocyte " idiosome " seems rarely to be well 

 developed, that the greatest confusion has prevailed. Indeed any 

 attempt to extract some fundamental conception from the maze 

 of description has thus far seemed hopeless. Viewing the prob- 

 lem as a whole, two facts alone stand out in seemingly universal 

 agreement, namely, (i) that there is always a body which comes 

 to lie at the anterior tip of the sperm and forms the acrosome of 

 authors, and (2) that in connection with this process there is 

 usually a remnant cast off and lost in the protoplasm of the tail 

 region. 



The second of these may require some notes in explanation. 

 From a general survey of spermatogenesis, I have found fairly 

 clear evidence of the elimination of some material formerly in 

 connection with the developing acrosome in many cases, of which 

 the following are a representative selection from widely separated 

 groups : 



Nematoda Ascaris (Hirschler, '13) 



Colecotera I Passatus ( Sch *fer, V) 

 | Cybister (Voinov, '03) 



Insecta 



Orthoptera 



I Gryllptalpa (Payne, '16) 

 [_ Locusta (Otte, '07) 



Pyrrhocoris (Henking, '91) 

 Hemiptera Anasa (p au i m i er , ' 99 ) 



[Euschistus (Montgomery, 'u) 

 Arachnida Lycosa (Boesenberg, '05) 



{Columbella (Schitz, '16) 

 Mollusca D , ,. /r > , 



\Paluaina (uatenby, 190) 



Amphibia Bufo (King, '07) 



Mus (Niessing, '97, v. Lenhossek, '98) 

 fBenda, '91, Niessing, '97, 



Mammalia 



Cavia\ v. Lenhossek, '98, 



[Sjoevall, '06, and others 

 Didelphys (Duesberg, '20) 



