88 J. BRONTE GATBNBY 



4. In the spermatooyte there is another group of granules 

 to be found, especially in Kopsch (OsOJ preparations. These 

 are individually much larger than the four members of the 

 group of yolk-granules, and are about ten to sixteen in number ; 

 they go brownish in OSO4. These larger granules have been 

 traced into the spermatid, where about three or four are present, 

 and appear to form the sides of the mitochondrial part of the 

 sperm-tail (PI. 1, tig. 2, x, and PI. 2, figs. 11 and 12, x). 



5. During the spermatocyte division prophases, the group 

 of yolk-granules is found to take up a position near the equator 

 of the sphidle (PI. 1, tig. 4, y), and subsequently becomes 

 divided into two smaller groups in later stages of the division 

 (PI. 1, tig. 5). This process occurs in both maturation divisions, 

 so that each spermatid contains about one-quarter of the 

 yolk-granules of the spermatid. The mitochondria, as is 

 generally the case during cell-division, become altered in such 

 a way that they form a tangled mass of thread-like bodies, 

 which are subequally sorted out into two portions, one in 

 each daughter-cell (PI. 1, figs. 4 and 5). The larger group of 

 granules which were thought to form part of the tail-sheath 

 were not found during mitosis. 



6. The newly-formed spermatid contains the usual inclusions 

 plus the group of yolk-granules (v in PI. 2, fig. 8). At this 

 stage the sperm-sheath granules are occasionally found, and 

 occur much more often in later stages (PI. 2, fig. 9, x). 



7. The spermateleosis stages, or metamorphosis of spermatid 

 into spermatozoon, are remarkable for the mamier of formation 

 of the tail-sheath. The mitochondria become grouped behind 

 the nucleus and around the outgrowing axial filament, while the 

 Golgi elements and yolk-granules take up a position behind 

 the mitochondria (PI. 2, fig. 9). Tail-sheath granules are 

 usually found in the vicinity (x in PI. 2, fig. 9). 



8. The mitochondria, hitherto single and all approximately 

 equal in size, now begin to run together, hke rain-drops, forming 

 groups of larger and smaller granules (PI. 2, fig. 10, mm and m). 

 This process goes on till only three large subequal spheres are 

 left (figs. 11,12, and 14), and then these spheres begin to elongate 



