330 The Theorv of Genetic Modes 



the entire point argued in the earlier pages of this work 

 untouched, i.e., that a real genetic series exhibits neiv 

 forms of organisatAon, new genetic modes, while not 

 violating the laws of the material which is organized. 



Consequently, it is quite on the right side to attempt to 

 carry further a theory of the actual method of the organi- 

 zation in the lines of physical explanation. Morgan does 

 this by the suggestion of a series of 'tensions,' made 

 in the last chapter of his book. To be sure, it amounts 

 to little more than suggesting a new term and with it a 

 certain way of looking at the phenomena of development, 

 serving the turn which the fine word ' polarity ' also served ; 

 yet the approach from the side of physics is justified, so 

 long as the problem of genetic mode — the interpreta- 

 tion of the longitudinal series — is not surreptitiously 

 brought in under that attempt, and smothered under the 

 new term. 



What the biologists need to do is to recognize the Hmi- 

 tations of one method, and the justification of the other in 

 its own province. In the life processes there seems to be 

 a real genetic series, an irreversible series. Each stage 

 exhibits a new form of organization. After it has hap- 

 pened, it is quite competent to show, by the formulas of 

 chemistry and physics, that the organization is possi- 

 ble and legitimate. Yet it is only by actual observation 

 and description of the facts in the development of the 

 organism, that the progress of the life principle can be 

 made out. The former is quantitative and analytic sci- 

 ence; the latter is genetic science.^ 



1 Morgan's somewhat biassed and decidedly inadequate discussion of the 

 natural selection theory of the origin of regeneration seems to show his fai'- 

 ure to recognize the need of naturalistic explanations. 



