228 



MICROSCOPIC ANATOMY OF THE ORGANS. 



Behind the head is the connecting part, body, or middle 

 piece ( Vst.), which is a cylindrical structure of about the same 

 length as the head, and 1 ^ wide. By means of special stains 

 we may distinguish in it an axial part and a capsule surround- 

 ing it (Ti, Sph., and Jf u ). The axis has a fibrillar structure 

 (axial threads), and begins in a thickening, the so-called termi- 

 nal globule (Ekn.). According to Meves, there are in man two 

 such bulbs closely connected with the head. Both on account 

 of staining reactions, and from histogenetic reasons, this end 



FIG. 177. 



Head 



Middle 

 ' piece 



Main piece 



Head' 



Middle 

 piece 



r 



End piece 



of 

 the 

 tail 



Spermatozoa of man. 



(After Retains.) At the left a surface view is shown ; at the right, a 

 lateral view. X 1200. 



bulb is believed to represent the centrosome of the cell. In the 

 process of fertilization also it plays this role. The capsule is 

 applied directly to the axial threads, and is continued along the 

 axis (ffi) to nearly the end of the tail. In many animals this 

 capsule has a spiral form, and is connected behind with an an- 

 nular thickening (Ss.). The outer capsule (-fiTn) shows in one 

 place a swelling and throughout its whole length a spiral 

 thickening (Sph.). 



In the tail we may distinguish two parts : the main segment 



