THE BEGINNINGS OF LIFE 



and Dr. Bastian is right in reminding us that it 

 is reasoning in a circle to assume the presence 

 of germs that cannot be detected, merely be- 

 cause there is no other way of accounting for 

 the presence of monads and bacteria in accord- 

 ance with the doctrine of Redi. 



For in all discussions concerning spontane- 

 ous generation, it should be borne in mind that 

 the doctrine omne vivum ex vivo is itself on trial 

 for its life, and cannot be summoned to the wit- 

 ness box. The very point to be ascertained is 

 whether this doctrine, which is admitted to hold 

 good in the case of all save the lowest forms of 

 life, holds good also of these. The doctrine rests 

 entirely upon induction ; and while, in many 

 cases, it is legitimate to infer a universal propo- 

 sition from a limited induction of instances, it 

 is not legitimate to do so in the present case. 

 For the fact that innumerable highly specialized 

 types of animal and vegetal life are kept up 

 solely by generation ex vivo can in nowise prove 

 that other living things, which are nearly or 

 quite destitute of specialization, may not have 

 their ranks recruited by a fresh evolution from 

 not-living materials. Along with the absence of 

 specialized structure, it may turn out that there 

 is an absence of other characteristics once sup- 

 posed to be common to all living things. 



This will be more clearly understood as we 

 proceed to consider the change which the last 



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