iv PREFATORY NOTE. 



Comparison of standpoints must benefit both sides. Cross- 

 fertilization works rejuvenation in theories as in organisms. 

 The biologist may pause to see how the individual vanishes in 

 the abyss of the universal, and how self-determination dissolves 

 in the presence of the physicist's fundamental postulate of 

 inertia. The physicist may find it agreeable from time to time 

 to turn from the Nirvana where self and not-self, rocked in 

 blissful reciprocity of vibration, annul each other, to the world 

 where self asserts itself in organic determinations issuing in 

 purposeful adaptations and conscious intelligent action. 



The inexperienced reader may need to be reminded that our 

 standpoints with reference to organic development are not 

 necessarily mechanical for the physicist, and vitalistic for the 

 biologist. Transcendental vitalism has just as little standing 

 on the biological as on the physical side. Indeed, if we were 

 to draw the line between mechanism and vitalism, it would be 

 found, unless I am much mistaken, that there are more physi- 

 cists than biologists on the side of vitalism. No less a 

 physicist than Lord Kelvin has recently declared that "the 

 influence of animal or vegetable life on matter is infinitely 

 beyond the range of any scientific inquiry hitherto entered on. 

 Its power of directing the motions of moving particles . . . 

 is infinitely different from any possible result of the fortuitous 

 concourse of atoms." l This may not be vitalism, but it does 

 not look like mechanism. 



It is on the biological side, strange as it may seem, that we 

 meet with extremes of mechanism, equalling, if not exceeding, 

 the discarded errors of vitalism. An epidemic of metaphysical 

 physics seems to be in progress a sort of neo-epigenesis. In 

 place of the vis essentialis of the old epigenesis, the new epi- 

 genesis sets up as its fetich the vis impressa. The new god is 

 preferred to the old because it works from the outside instead 

 of the inside. It represents the sum of external conditions 

 and influences at the present moment, and is proclaimed all- 

 sufficient for building up organisms out of isotropic corpuscles. 

 Previous conditions are not, indeed, quite ignored, for they have 

 resulted in special molecular constitutions called germs, and 



1 Fortnightly Review, 1892. 



