On the Mechanical Conception of Nature. 643 



sition of new facts of the knowledge that the 

 same compounds which compose organic bodies 

 can be produced without the latter. This dis- 

 covery, due to Wohler and his followers, showed 

 that organic products could be prepared arti- 

 ficially. 4 In brief, the decline of the vital force 

 followed from the knowledge that at least one 

 portion of the processes of life was governed by 

 known forces. 



But in the domain of the development of the 

 organic world have we not quite analogous proofs 

 of the efficacy of known forces ? Is not the 

 variability of all types of forms a fact ? and 

 must not this under the action of natural selection 

 and heredity lead to permanent changes ? Has 

 not the problem of explaining the subserviency of 

 all organic form to law as a result without in- 

 voking its aid as a principle been thus success- 

 fully solved ? It is true that we have not directly 

 observed the process of natural selection from 

 beginning to end ; neither has anybody directly 



* [The discovery here referred Jo is the synthesis of urea 

 by Wohler in 1828 (Pogg. Ann. xii., 253; xv. 619), by the 

 molecular transformation of ammonium cyanate. Since that 

 period large numbers of organic syntheses have been effected 

 by chemists, and many of the compounds formerly supposed 

 to be essential products of life have been built up in the 

 laboratory from their inorganic elements. The division of 

 chemistry into " organic " and " inorganic " is thus purely arti- 

 ficial, and is merely retained as a matter of convenience, the 

 former division of the science being defined as the chemistry 

 of the carbon compounds. R. M.] 



