98 BIOGENESIS AND HOMOGENESIS LESS. 



tain millions of Bacteria instead of one. This means, of 

 course, that a certain amount of fresh living protoplasm has 

 been formed out of the 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 ; and there is no a priori reason why it 

 should be impossible to imitate the unknown conditions 

 under which this took place. At present, however, we have 

 absolutely no data towards the solution of this fundamental 

 problem. 



But however insoluble may be the question as to how life 

 first dawned upon our planet, the origin of living things at 

 the present day is capable of investigation in the ordinary 

 way of observation and experiment. The problem may be 

 stated as follows : any putrescible infusion, i.e. any fluid 

 capable of putrefaction will be found after a longer or 

 shorter exposure to swarm with bacteria and monads : do 

 these organisms or the spores from which they first arise 

 reach the infusion from without, or are they generated within 

 it? And the general lines upon which an investigation 

 into the problem must be conducted are simple : given a 

 vessel of any putrescible infusion ; let this be subjected to 

 some process which, without rendering it incapable of sup- 

 porting life, shall kill any living things contained in it ; let 

 it then be placed under such circumstances that no living 

 particles, however small, can reach it from without. If, 



