THE PHYSICAL BASIS OF LIFE 85 



But it is not merely variations which present 

 difficulties. The almost indefinite variety of qualities 

 which are obviously stored up in the atom are just as 

 embarrassing. These, like the variations themselves, 

 can, as it seems, be accounted for in the same way. 

 Minute perturbation in the motion of these aggre- 

 gates might be sufficient to give rise to marked 

 qualities in the fully developed organism. A pug- 

 nose or red hair may be handed down from generation 

 to generation as some slight disturbance or perturba- 

 tion in the configuration of a particular third motion 

 in some comparatively stable and important group. 



We thus perceive the vast complexity of these 

 unintelligible germs. How very difi"erent must they 

 be from anything that we should now produce even 

 by the most complex of artificial means ! 



The incalculable conditions under which they, and, 

 still more so, their remotest ancestors, have had to 

 exist, leave a blank which no scientific facts can 

 unravel nor speculative thought can penetrate. The 

 most that can be hazarded is that, as to-day we can 

 see taking place under our eyes the development of 

 certain primitive or elementary germs, under certain 

 conditions purely artificial, in the laboratory, as the 

 hot-house produces a plant with which all Nature 

 cannot vie, so may we reason backwards in thought to 

 the time when some unknown conditions should have 

 given rise to something somewhat similar, but, as 

 we must admit, still difi"erent from those micro- 

 organisms that as by some wild guess we have 

 succeeded amidst many failures in producing to-day. 



