Ill SPONTANEOUS GENERATION 283 



constituents of the hay-infusion, through the agency in the 

 first instance of a single living Bacterium. The question 

 naturally arises, Why may not the formation of protoplasm 

 take place independently of this insignificant speck of living 

 matter ? 



It must not be thought that this question is in any way 

 a vain or absurd one. That living protoplasm has at some 

 period of the world's history originated from not-living 

 matter seems a necessary corollary of the doctrine of 

 evolution, and is obviously the very essence of the doctrine 

 of special creation (p. 221); and there is no d Jin'ori reason 

 why it should be impossible to imitate the unknown con- 

 ditions under which the process took place. But at present 

 we have absolutely no data towards the solution of this 

 fundamental problem. 



Experiments conducted with proper precautions, however, 

 all tell the same tale : they prove conclusively that in 

 putrescible infusions that have been properly sterilized, — i.e. 

 thoroughly boiled so as to kill any organisms they may 

 contain— and adequately protected from the entrance of 

 atmospheric germs, no micro-organisms ever make their 

 appearance. So that the last argument for abiogenesis has 

 been proved to be fallacious, and the doctrine of biogenesis 

 shown, as conclusively as observation and experiment can 

 show it, to be of universal application as far as existing 

 conditions known to us are concerned. It is also 

 necessary to add that the presence of microbes in consider- 

 able quantities in our atmosphere has been proved 

 experimentally. 



There is another question intimately connected with that 

 of Biogenesis, although strictly speaking quite independent 

 of it. It is a matter of common observation that, in both 

 animals and plants, like produces like : that a cutting from 



