On the Mechanical Conception of Nature. 679 



Whether such a homogeneous root ever existed is 

 however doubtful ; it is much more probable that 

 numerous organisms first arose spontaneously, 15 

 and these cannot be presumed to have been abso- 

 lutely equal, since the conditions under which 

 they came into life cannot have been perfectly 

 identical. Let us, however, for the sake of sim- 

 plicity assume a single primordial organism ; the 

 first generation which took its rise from this by 

 reproduction could only have possessed such 

 individual differences as were produced by the 

 action of dissimilar external influences. But the 

 third generation, together with self-acquired, 

 would also have shown inherited, dissimilarities, 

 and in each succeeding generation the number of 

 tendencies to individual difference imparted to the 

 germ by heredity must have increased to a certain 

 degree, so that it may be said that all germs, 



18 [Although hardly necessary to the evolutionist, it may 

 perhaps be well to remind the general reader, that all ex- 

 periments upon spontaneous generation, or abiogenesis, have 

 hitherto yielded negative results ; no life is produced when the 

 proper precautions are taken for excluding atmospheric germs. 

 But although we have so far failed to reproduce in our 

 laboratories the peculiar combination of conditions necessary 

 to endow colloidal organic matter with the property of 

 " vitality," the consistent evolutionist is bound to believe, 

 from the analogy of the whole of the processes of nature, that 

 at some period of the earth's history the necessary physical and 

 chemical conditions obtained, and that some simple form or 

 forms of life arose " spontaneously," /". e. by the operation of 

 natural causes. R. M.] 





