626 NATHAN FASTEN 



shape and about half the size of those found in the polar view 

 of the reduction division. 



17. When type A divides, most generally both chromatoid 

 bodies migrate to one pole of the spindle. In rarer cases, each 

 of the chromatoid bodies may migrate to opposite poles of the 

 spindle. 



18. During the division of type B, the one chromatoid body 

 migrates to one pole, leaving the opposite pole without any. 



19. When type C divides, the spermatids produced do not con- 

 tain any chromatoid bodies. 



20. The resulting spermatids are thus of three types: type A', 

 with two chromatoid elements; type B', containing one chro- 

 matoid element; and type C, without any chromatoid elements. 

 Type C is the most common form, being about four times as 

 numerous as either of the other two types. 



21. All traces of these chromatoid bodies are lost when the 

 spermatid begins its transformation to form the spermatozoon. 



22. The nucleus of the spermatid becomes disc-shaped and 

 migrates to one pole of the cell. At the opposite pole a vacuole 

 appears which is filled with a glue-like fluid. The centrosome 

 migrates between these two structures. 



23. The vacuole forms the refractive vesicle of the sperm; 

 the nucleus forms the head-piece, while the centrosome sends out 

 fine ray-like fibers along which the radial arms of the spermatozoon 

 are developed from the rest of the cytoplasm. 



■ 24. The mature spermatozoon is a highly refractive spheroidal 

 body, with the radial arms closely packed around the nucleus 

 in the form of a cup which appears transparent and watery in 

 consistency. 



25. In Ringer's solution, in water, and in various Na and K 

 salts, the opening out of the spermatozoon can best be studied. 

 In Ringeu's solution the radial arms uncoil slowly and the vesicle 

 swells. In many cases, the vesicle undergoes a transformation 

 by means of which its involuted edges straighten out. In water 

 this was especially well seen. 



26. Osmotic phenomena of the sperm are, undoubtedly, 

 responsible for these transformations in the vesicle. 



