110 



ZOOLOGY 



small granule termed the acrosomal granule (Fig. 56, B, C). The 

 gr^anular acrosome is found in Paludina (Gatenby), and Columbella 

 (Schizt). The exact character of the granule is not clear. It 

 may be either the limiting type of the vesicular acrosome or else 

 the acrosomal granule itself without any vesicle surrounding it. 

 The remains of the acroblast, known as the Golgi remnant, pass 

 down the tail and are sloughed off with the residual protoplasm, 



/433. 



Ai.gr 



CAs. 



Fig. 56. — Diagrams to illustrate the formation of the acrosome. 

 A, B and C, in Hemipteran spermatids. D, E and F, in mam- 

 malian spermatids (from Bowen (IOd) ) ; (A, B and C, after 

 Bowen ; D, after Lenhossek ; E, after Meves ; F, after Gatenby 

 and Woodger), Ah., acroblast ; As., acrosomal vesicle ; 

 Ass., acrosomal vesicles ; As.gr., acrosomal granule ; C.As., 

 compound acrosome ; G., golgi material ; G.r., golgi remnant ; 

 /,, idiosome ; A^, nucleus. 



while the acrosome comes to lie at the tip of the metamorphosing 

 spermatozoon (Fig. 56, C). Either the acrosome is deposited by 

 the acroblast on the nuclear membrane, whence it moves over the 

 surface until the required position is taken up (e.g., Hemiptera), 

 or else, as in the case of mammals, the acroblast accompanies it 

 to the tip, deposits it in situ, and then moves back down the tail. 

 In other forms, such as the grasshoppers, moths, etc. (3, 4, etc.), 

 although the essential character of the process is the same, 



