42 The Unity of the Organism 



widely different from those of Loeb. According to my view, 

 the question is not one to be settled by discussion at all, 

 but by observation coupled with a measure of consistent 

 reasoning. Assuming that I am right, to "transfer" the 

 problem "from the field of histology" if this really means, 

 as it seems to, that the problem should be taken away from 

 histology, no matter whether to the field of chemistry or 

 any other, would be to remove it all the further from ob- 

 servation and plunge it so much the deeper into discussion. 

 I have not the slightest doubt that chemistry, especially 

 biochemistry pursued on the principles of physical chem- 

 istry, will have to be made large use of before the fullest 

 possible understanding of the mechanism of heredity is 

 reached. But this use will have to go hand in hand not 

 only with morphological studies on germ-cells, but as well 

 on hosts of cells during the whole ontogeny. Chemical in- 

 vestigation will have to supplement, it cannot supplant, it 

 cannot even lead, histogenic investigation. If there is one 

 thing made more positive than any other about heredity by 

 modern study of the subject, it is that heredity is some- 

 thing which pertains to the smaller taxonomic grades of 

 organisms, races, varieties, species and so forth. It would 

 seem, accordingly, that hardly any suggestion for the study 

 of heredity could be wider of the mark than one to trans- 

 fer it from the only field which makes any pretense of in- 

 vestigating the details of development, and taking it into 

 a field like that of physico-chemical activity, which is no- 

 toriously devoid of the very attributes without which there 

 would be no such thing as heredity. Having once ascer- 

 tained by observation as much as possible about how hered- 

 itary attributes are actually produced, it will then be in 

 order to learn as much as possible about the chemistry of 

 the processes. Chemistry can do its share in solving the 

 problems of heredity after and not before histogenesis has 

 done its share. 



