164 



THE GERM-CELLS 



to degenerate without contributing directly to the sperm-formation 

 {Helix). The chromatoid Nebenkorper, finally, is a small rounded 

 body, staining with plasma-stains, which appear always to degenerate 

 without taking direct part in the formation of the spermatozoon. It 

 is possibly an extruded nucleolus ( Lenhossek ). but its origin and 

 meaning are not definitely known. 



(r) Traiisforniation of the Spermatid into tJie Spennatozobii. — In 

 the works of earlier authors it is often impossible to distinguish 



Pig, 3^. — Formation of the spermatozoon from the spermatid in the salamander. [HER- 

 MANN.] 



A. Young spermatid, showing the nucleus above, and below the colourless sphere, the ring, 

 and the chromatic sphere. D. Later stage, showing the chromatic sphere and ring at the base 

 of the nucleus. C. D. E. F. Later stages, showing the transformation of the chromatic sphere into 

 the middle-piece (?«). 



which of the various achromatic elements mentioned above have been 

 under observation. We may therefore confine ourselves mainly to 

 the latest works, in which these distinctions are clearly recognized. 

 Owing to their great size, the spermatozoa of Amphibia have been 

 the subject of most careful study; yet a clearer view of the subject 



