378 SYNAPSIS; SPERMATIDIAN GRANULES 



a more or less orderly (e.g., more or less definitely oriented) extrusion 

 from the spermatids of structureless looking chromatoid substance, 

 (chrtd Fig. 2 and Fig. 14), barely possibly by a very "degenerate" 

 mitosis; these chromatoid masses are soon absorbed. 



"Normally," the four cells just described would develop into four 

 sperms, but here the spermatogenesis proceeds as follows: Moving 

 along the testis with soldier-like precision, the two caudad members 



.nd 



H200 

 Fig. 5 



Fig. 5. Nucleus of full grown spermatocyte seen in synapsis. The nuclear mem- 

 brane is still intact and the spherical nucleolus is still visible. The chromosomes are 

 in seven pairs. It was possible to resolve the chromosomes into numerous components, 

 suggesting a possible explanation of the difference in chromosome counts in certain 

 nemas, e.g., in Ascaris; i.e., differences between counts at this stage and counts in later 

 somatic divisions; for, should such loosely organized chromosomes later break apart, 

 the count would be much increased. 



Fig. 6. A single spermatidium of first generation with its nucleus and sixteen 

 granules. From life. In this case the cell wall is shown. 



Fig. 7. Above, camera lucida drawing of nuclei and granules in spermatidia of 

 S. parasitifera at the point grn (4), Fig. 2. Below a diagram of four spermatidia. The 

 diagram is derived from drawing above, and shows more clearly the numerical rela- 

 tionships of nuclei and granules. The boundaries of the spermatidia are almost in- 

 visible and are not shown. The granules are shown black, white or, when seen through 

 the nucleus, gray. The larger ellipsoidal objects are nuclei. In the drawing, at top 

 and on the hither side, a nucleus with its accompanying four granules, the nucleus 

 being this side of granules. In the drawing, on the farther side, again at top, a sperma- 

 tidium three of whose granules have already given rise to four smaller granules each. 

 In the drawing and below, a spermatidium none of whose four granules have divided, 

 one of them shown behind the nucleus, grn (16) shows a spermatidium with a nucleus 

 and 16 granules. The lower figure is only somewhat schematised. Very rarely are 

 spermatidian cells so systematically arranged as to disclose so clearly the relationships 

 of granules and nuclei. In this diagrammatic lower figure the far spermatidium is 

 shown in an intermediate state. Illustration derived from material stained with 

 methyl green. 



of the quartet form a tandem, followed by the other two, also in 

 tandem; i.e., the quartet falls into single file. These spermatids in 

 file grow, and one after another divide internally without evidence 

 of mitosis into 64 uninucleate elements which proceed to surround 

 themselves with walls and form a tissue of 64 cells. (See lowest part 

 of Fig. 2.) As this tissue leaves the testis and enters the duct it 



