316 PHYSIOLOGICAL GENETICS 



models arc available for a proportional chemical action with 

 different degrees of methylation, etc. As a matter of fact, the 

 concept of the gene, which considers its primary property to be 

 its quantity, will be most easily incorporated into the new hypo- 

 thesis and will turn out to have been a better guess than most of 

 t he o1 her concepts (see page 293). This docs not mean, however, 

 that such physical considerations as those discussed above 

 (Timofeeff, Zimmer, and Delbrueck) are not valid. They actu- 

 al ly lead only to the conclusion that the elementary quantum 

 process produces secondary changes of atomic equilibrium. 

 One of these is also a dissociation of bonds, which, after all, 

 would also be needed for the breakage of a chain molecule. 

 There is, then, no obstacle from the side of physics to changing 

 the concept of the gene in the direction here espoused. As a 

 matter of fact, I had reached this conclusion years before the 

 physical analysis of the three authors was published (see 

 quotation, page 301). 



A second point concerns the problems of how evolutionary 

 changes occur and whether or not chemical changes in the residues 

 as opposed to steric changes in the chain molecule are of primary 

 importance. No facts based on experimentation are yet known 

 that permit conclusions on this point. But it would be a mistake 

 to reject necessary conclusions concerning the gene concept, 

 because they will not lead to an explanation of everything. 



Views regarding the gene as developed in this chapter have been 

 "in the air" for some time. Goldschmidt's remarks (1930a) 

 have been quoted, and it may be added that he has discussed the 

 contents of this chapter repeatedly in public during the past years. 

 The Drosophila workers, while discussing the position effect, 

 touched upon it; and Muller (1935) almost drew such conclusions 

 though shrinking, as it seems, from the last step, namely the 

 abolition of the gene concept. The chemical models used by 

 Koltzoff and the more modern one by Wrinch are also steps 

 toward the views developed here. It remains for the physico- 

 chemist to decide whether or not the new model could also take 

 care of the independent catalytic actions of what was considered 

 to be a gene. 



