8 J. BRONTE GATENBY 



(«) 8 p c r m a t e 1 e o s i s . 



The spermateleosis stages comprising those leading to the 

 metamorphosis of spermatid into spermatozoon are very 

 pecuhar. The mitochondria, wliich in PL 2, tig. 9, He grouped 

 behind the nucleus, l)egin to run together as depicted in tig. 10. 

 Three main centres for this coalescence! exist, but here and 

 there a few separate centres exist ; these ultimately join up 

 with one of the larger centres, till one gets such a stage as 

 in PI. 2, fig. 11, where three balls of mitoclnmdrial substance 

 are produced (mm), while the remainder of the free mito- 

 chondria are gradually fusing up. 13y the stage of fig. 12 

 the mitochondria have all fused to form three solid spheres 

 generally somewhat untHjual in size, and as well, often in 

 staining aitinity. In PI. 2, fig. 14, the three spheres are viewed 

 from below, their unequal size being apparent. 



Leaving the mitochondria at this stage, the fate of the yolk- 

 si)herules and of the Golgi elements may be described ; at 

 such a stage as in fig. 10 of PL 2 the Golgi elements lie behind 

 the zone of the mitochondria ; as the mitochondria fuse up, 

 the Golgi elements keep behind the most distal mitochondria 

 as in PL 2, fig. 11, and, finally, when all the mitochondria have 

 fused to form the three spheres, the Golgi elements lie close up 

 behind as in PL 2, fig. 12. In the case of the yolk-spherules 

 a somewhat similar change in position has been noted : in 

 PL 2, fig. 10, the yolk-spherules are on the right of the cell, 

 but by stages in figs. 11 and 12 they have moved back behind 

 the mitochondrial spheres. 



In many, but not all, examples there can be observed 

 between the three mitochondrial spheres, a small, often round, 

 often angular grain, as in PL 2, fig. 14, at x. In figs. 9, 10, 11, 

 and 12 such bodies are also seen. 



These bodies, I believe, are derived from the grains marked 

 X in PL 1, fig. 2. They seem to form a part of the mitochondrial 

 sheath of the sperm-tail. 



The spermatid at such a stage as that of fig. 12 now begins 

 to lengthen. In PL 2, fig. 13, the three mitochondrial spheres 



