nature: and cause: of variation. 305 



only 100,000 determinants — a number far below Weismann's supposition for 

 insects — we shall have on this basis 5 X 2 X 100,000, or 1,000,000 organic 

 molecules compressed into the space of 0.0000225 c. mrn. Now, it is obvious 

 that the initial five molecules can not be the simple CH groups, but are 

 extremely complex and large molecules, and each molecule can have but the 

 0.000,000,000,022,5 c. mm. of space, and this only upon the basis that the 

 chromatin is absolutely solid, with no space for molecular movement. We 

 know, however, that the chromatin as we can see it is not solid, but is more or 

 less an aggregation of particles ; and if we follow out the idea, each of the 

 necessary 1,000,000 molecules in the assumption has certainly far less than 

 the 0.000,000,000,022,5 c. mmi. in cubic contents. It is obvious from this data 

 that, giving the id-determinant-biophore hypothesis every chance and the ben- 

 efit of every doubt, there still remains the insurmountable difficulty that it 

 "can only" in a superficial way explain up to a certain point, but when pushed 

 beyond that point it fails utterly. As a general conception of development 

 and evolution the Weismannian id-determinant-biophore hypothesis does not 

 stand the test of examination and trial in the light of our present knowledge 

 of organic activity. 



How shall we conceive of the germ plasm? Most obviously, in order to 

 investigate variation and the method of evolution, we must form some con- 

 ception of the nature of the germ plasm. Whether the chromatin is the germ 

 plasm or not, we know it to be an extremely complicated series of complex 

 organic substances constantly in process of chemical change, and giving off 

 elaborated cell products for diverse purposes. As far as we have any real 

 knowledge, the chromatin is wholly concerned in metabolic processes, and 

 although it is the most complicated and most discussed material in the cell, 

 especially in cell reproduction, the fact is undeniable that the part taken by the 

 chromatin in the process of reproduction is much more passive than that 

 taken by the plasma. Cell division or cell reproduction is an activity in 

 which many of the important elements are non-chromatic, and are as constant 

 structures as the chromatin, even though not so strikingly present in cyto- 

 logical preparations. Sensation, motion, and the mechanism of reproduction 

 lie in the materials outside of the chromatin ; the trophic activities lie, as far 

 as our knowledge goes, within the chromatin. 



It is undeniably true that the plasma is nourished or even perhaps derived 

 from the nucleus — that is, there is growth of the plasma — but we never find 

 chromatin without plasma, nor plasma without chromatin. They are interde- 

 pendent. The plasma is the seat of response, motion, and the mechanism of 

 reproduction ; the chromxatin is the seat of m.etabolic activity, and they can not 

 be separated. We can no more say that since the plasma grows at the expense 

 of the activity of the chromatin, the chromatin is primary and the plasma 

 secondary, than we can argue that the metabolic mechanism of man is 



