PLATE 3 



EXPLANATION OF FIGURES 



15 Spermatid exhibiting differentiation of the striated layer into two regions, 

 disintegration of vesicular bodies, deposition of oil droplets (o.d.) and the com- 

 pletion of the mitochondrial ring (m.r.). 



16 Section of the cell perpendicular to that of figure 15, showing the form of 

 the mitochondrial ring. 



17 and 18 Two stages preceding the invagination of the spermatid. The 

 vesicular bodies vanish, additional oil droplets appear and in the striated layer 

 the formation of cilia-like processes (c.p.) begins. 



19 and 20 Two stages in the development of the invagination cavity (i.e.). 



672 



