4OO EDMUND B. WILSON. 



again moved forward to its definitive position at the anterior pole 

 of the nucleus the chromatoid body is always in the tail (some- 

 times much earlier), often at a considerable distance from the 

 head. 



As the elongation of the tails proceeds, the chromatoid body 

 is carried still further away from the head, finally reaching a 

 position in the middle tail-region. When the nuclei have become 

 elongate, homogeneous and intensely staining, and the immature 

 spermatozoa are aggregated in parallel bundles, the chromatoid 

 bodies are still conspicuously seen (particularly well in the 

 safranin-green preparations) scattered irregularly within the 

 bundles of sperm-tails. They are at this time still enclosed 

 within the tails, lying in the protoplasm outside the chondrio- 

 some-envelope of the axial filament; but their elimination shortly 

 takes place. This process is preceded by a marked accumulation 

 of protoplasm that forms a swelling at one side of the tail within 

 which the chromatoid body lies (Figs. 44, 45) ; but similar swel- 

 lings are also seen in the spermatids that contain no chromatoid 

 bodies. That these protoplasmic masses are sloughed off in both 

 cases is certain from the ensuing and final stage, though in my 

 rather scanty material I have never been able to catch the process 

 in the very act. In the succeeding stages numerous protoplasmic 

 balls are found lying between the tails (usually more or less 

 definitely aggregated near the middle tail-region of the bundle) 

 and quite separate from them (Fig. 46). It may now be seen 

 with perfect clearness that the chromatoid bodies have been 

 cast off with the protoplasmic balls; for they are now never 

 within the tails but are still perfectly evident in many of the free 

 protoplasmic balls. Counts of the latter show that the chroma- 

 toid body is present in about one fourth of them. It still stains 

 as intensely as ever, and is often quite unchanged, but in many 

 cases has now assumed a crescentic shape, as if the central cavity 

 had broken through to the exterior at one side (Fig. 45). 



These facts seems to admit of no other interpretation than that 

 a considerable mass of protoplasm is sloughed off from each 

 spermatid, and that it carries with it the chromatoid body when 

 present. It is certain that the latter does not contribute in any 

 visible way to the formation of the spermatozoon. 1 



