vn] NEBENKERN 101 



GATENBY'S later papers (1919 , c} bring these and other 

 observations on the acrosome into a comprehensive scheme 

 by indicating that the acroblasts of Lepidoptera, and 

 possibly the acrosome generally, belongs to the Golgi 

 apparatus. The acroblasts are at first Golgi rods, of the 

 typical crescent shape, and with the typical relation to the 

 mitotic spindle. In the later stages they become vesicular, 

 and appear to 'unite to produce the acrosome as described. 

 In Molluscs (GATE N BY, 1917 , 1918 a) the Golgi rods of the 

 spermatocyte are at first very similar, but in the spermatid, 

 instead of becoming attached to the nucleus at the anterior 

 end of the developing spermatozoon, they arrange them- 

 selves around a dense " archoplasmic " mass behind the 

 nucleus, and with it constitute the so-called "Nebenkern." 

 As the spermatid elongates, this Nebenkern, consisting of 

 Golgi rods and archoplasm, passes gradually down the tail 

 and appears finally to be sloughed off. Meanwhile a small 

 acrosome, of unknown origin, appears at the anterior side 

 of the nucleus; by analogy with the Lepidoptera it seems 

 possible that further investigation may show that this is 

 derived from a portion of the Golgi apparatus separated off 

 from the rest. Like the mitochondria, therefore, the Golgi 

 bodies, while possibly deserving the name of cell-organs, 

 appear to be concerned with cell-differentiation, and can 

 hardly be considered as specific structures having an invari- 

 able function, since their fate differs so widely in sperma- 

 tozoa of different animals. 



The rather complicated processes which take place in the 

 later stages of spermatogenesis may be summarised as 

 follows. The greater part of the head consists of the nucleus 

 which develops directly from that of the spermatid by a 

 process of contraction and concentration. The acrosome is 

 described in some forms as arising from a mass of denser 



