LIFE AS MECHANISM 



that even the most elementary attention to form in 

 its relation to growth would have removed most of 

 Darwin's difficulties in regard to the particular phe- 

 nomena which he is here considering. For these phe- 

 nomena are phenomena of form, and therefore of 

 relative magnitude; and the magnitudes in question 

 are attained by growth, proceeding with certain spe- 

 cific velocities and lasting for certain long periods of 

 time. And it is accordingly obvious that in any two 

 related individuals (whether specifically identical or 

 not) the differences between them must manifest 

 themselves gradually, and be but little apparent in 

 the young. It is for the same simple reason that ani- 

 mals which are of very different sizes when adult, 

 differ less and less in size (as well as in form) as we 

 trace them backwards through the foetal stages.""^ 

 This statement would point to the uselessness of em- 

 bryological similarities as a proof of evolution, and 

 Thompson, himself, is very sceptical about all our 

 theories of its proof. But, as I pointed out previously, 

 there is no use in depending on biologists to advise us 

 to give up evolution as a scientific law and gospel, for 

 note Thompson's subsequent attitude. His reasoning 

 should be, if embryos must be more and more alike 

 the earlier the stage of their development, then their 

 first appearance, that of the ovum, should be quite in- 

 distinguishable amongst all the forms of living organ- 

 isms, which is an observed fact. Is there any escape 



21 On Growth and Form, 1917, p. 59. 



C 279 3 



