66 FUNCTIONAL INERTIA 



impulses, a centripetal which tends to preserve and 

 transmit the specific form and which he identifies 

 with heredity, and a centrifugal which results from 

 the tendency of external conditions to modify the 

 organism and effect its adaptation to themselves. 

 The internal impulse is conservative and tends to 

 the preservation of specific or individual form, the 

 external impulse is metamorphic and tends to the 

 modification of specific individual form." Professor 

 Haeckel comes within a very little of speaking 

 of inertia and affectability in this passage un- 

 doubtedly what I mean by the former he designates 

 the u internal impulse " with its conservative 

 tendency tending to preserve, while the latter is, o^ 

 course, only another name for that which underlies 

 the modinabihty of the organism. Haeckel does, 

 as I do, identify the internal conservative tendency 

 with heredity. I may say that I first read the 

 above passage, four years after I had published my 

 first paper. Naturally I was confirmed in my 

 manner of viewing the properties of protoplasm 

 when I found that I had the unconscious support of 

 one of the greatest of living biologists. Haeckel 

 clearly recognises the antithesis between environ- 

 ment related to affectability on the one hand, and 

 the internal impulse to preserve the inherited status 

 quo on the other : on this latter the environment is 

 powerless. If one property, affectability, underlies 

 the tendency to correspond with environment, it 

 is impossible that the same property can simul- 

 taneously underlie an entirely opposite tendency, 



