Evidence from Metazoan Germ-Cells 5 



mammalian spermatozoon (figure 36) of the Fur Seal. 



For the origin of the various parts we will make use of 

 the summary given by Ballowitz (figure 37). Concerning 



FIGURE 37. "YOUNG" SPEHMATID (AFTER BALLOWITZ). 



1, nucleus. 2, centrioles. 3, idiosome. 4, mitochondrial body. 5, 

 chromatoid body. 6, spindle remnant. 



the nucleus, ./, "it is certain that in all animals the chroma- 

 tin-containing part of the sperm proceeds from the 

 nucleus." 3 On this point there is agreement among observ- 

 ers ; so whatever may be the truth about the sperm-chromatin 



FIGURE 38. SPERMATID OF FUR SEAL (AFTER OLIVER). 



n., nucleus, c., centrioles. a.f., axial filament. 



as the physical basis of heredity for the adult animal, there 

 is no question about its being such for the head of the 

 spermatozoon itself. 



