PREFATORY NOTE.- V 



these display peculiar molecular activities known as metab- 

 olism, growth, and division. The long past can bring forth 

 only a molecular basis ; a few hours of the present can supply 

 all, or nearly all, the determinations of the most complex 

 organism. Impotent past, prepotent present. We have no 

 longer any use for the " Ahnengallerie " of phylogeny. He- 

 redity does not explain itself or anything else, and it detracts 

 from the omnipotence and universality of molecular epigenetics. 

 We are no better off for knowing that we have eyes because 

 our ancestors had eyes. If our eyes resemble theirs it is not 

 on account of genealogical connection, but because the molecu- 

 lar germinal basis is developed under similar conditions. The 

 reason this basis becomes an eye rather than an ear or some 

 other organ is wholly due to its position and surroundings, not 

 to any inherent predeterminations. If the material for the eye 

 and the ear could be interchanged in the molecular germ, that 

 which in one place would become eye would in the other place 

 become ear, and vice versa. All this is credited to " develop- 

 mental mechanics," for which we have the highest respect so 

 long as it is really "developmental." But the "mechanics" 

 of "exovates" seems to be peculiarly innocent of any knowl- 

 edge of nature's experiments. 



While biology is certainly indebted to physics for some of 

 its metaphysics, it is to the credit of physics to have made it 

 clear that mechanism, indispensable as are its methods, affords 

 no fundamental explanation of anything. As Karl Pearson has 

 so well said, the mystery of life is " no less or no greater 

 because a dance of organic corpuscles is at bottom a dance of 

 inorganic atoms." ^ What dances and why it dances is not ex- 

 plained by reducing size to the lowest limit of divisibihty, and 

 just as little by the assumption of ultra-physical causes. This 

 is no criticism — no disparagement; it is only a confession of 

 ignorance. The ultimate mystery is beyond the reach of both 

 mechanism and vitalism ; let pretension be dropped, and 

 approximation to truth will be closer on both sides. 



When neo-epigenesis objects to anything previous, if it be 

 above a physical molecule, because what is done must be sub- 



1 Grammar of Science, p. 407. 



