1 66 



THE GERM-CELLS 



consisting of three parts, lying side by side in the cytoplasm (Fig. 83). 

 These are {a) a colourless sphere, shown by Meves's later researches to 

 be probably an attraction-sphere ; (/>) a minute, intensely staining cor- 

 puscle, and (r) a small, deeply staining ring. The concurrent results 

 of Hermann ('89, '92, '97), Benda ('93), and Meves ('96, '97, 2) have 

 shown that the small corpuscle {c) is one of the centrosomes of the 

 spermatid, and all these observers agree that it passes into or gives 



/ y 



n w^ 



Fig. 84. — Formation of the spermatozoon in Amphibia. [A-E. Salaviandra, MEVES; 

 F-K. Amphuima, McGrec;or.] 



A. Spermatid with peripheral pair of centrosomes lying outside the sphere, and axial filament. 

 B. Centrosomes near the nucleus, outer one ring-shaped. C. Inner centrosome inside the 

 nucleus, enlarging to form middle-piecei D. Portion of much older spermatid, showing divergence 

 of two halves of the ring (;-). E. Portion of mature spermatozoon, showing upper half of ring at 

 r, and the axial filament proceeding from it. 



F. Spermatid of Amphiuma, showing sphere-bridges and ring-shaped mid-bodies. G. Later 

 stage ; outer centrosome ring-shaped, inner one double ; sphere (j) converted into the acrosome. 

 //. Migration of the centrosomes. /. Middle-piece at base of nucleus. % The inner centrosome 

 forms the end-knob within the middle-piece, which is now inside the nucleus. K. Enlargement of 

 middle-piece, end-knob within it ; elongation of the ring. 



