Evidence from Metazoan Germ-Cells 27 



called by him yolk-niatrix and considered by Conklln to be 

 the same as wliat he calls sphere material, arises from the 

 nucleus, this belief rests not on direct evidence of the pass- 

 age of the substance from the nucleus into the cytoj)la.Mii, 

 but on the facts that when the substance is first seen in 

 the oocyte it is a small mass situated in the cell-bod v or 

 cytoplasm close in contact with the nuclear wall, and that it 

 reacts to stains and digestive fluids in the same wav that 

 certain granular contents of the nucleus react. But Cramp- 

 ton is very explicit in pointing out that this substance in the 

 nucleus is not chromatin, at least of the ordinary kind. 

 Upon treating the cells with digestive fluids it disappears 

 from both inside and outside the nucleus, the true chromatin 

 being then left in clear view as fine granules in the nuclear 

 reticulum. 



So far as concerns the endoplasm, then, even thougli it 

 be derived from s})here material and this in turn from the nu- 

 cleus, the most trustworthy evidence we possess is to the 

 effect that its primal nuclear source is not chromatin. In 

 view of such facts as these, made known by Crampton and 

 others, through what reasoning would Conklin, to whom the 

 facts are familiar, still hold that taken all-in-all they su}>- 

 port the chromatin dogma of heredity.^ Readers wliose 

 minds have become sensitized to the general type of reason- 

 ing which pervades nearly all elementalistic theorizing and 

 makes it to some extent fallacious, will readily anticipate 

 about how the argument will run in this case. But it will 

 be profitable to see it in actuality. After saying that ^'sonie 

 of the important cytoplasmic substances can be actually 

 seen to come from the nucleus" but that "this does not indi- 

 cate that these substances exist from the beginning in the 

 nucleus; on the contrary there is direct and visible evidence 

 that they arise epigenetically," Conklin continues : **Such 

 epigenesis, however, does not signify lack of primary organ- 

 ization ; on the other hand all the evidence favors the vlrw 



