DOMAIN OF EVOLUTIONARY HYPOTHESIS 105 



the acceptance of spontaneous generation for which 

 he himself can find no grounds at all a philosophical 

 need. 



With the reason for this Hackel should provide him ; 

 he says : ' We must regard this hypothesis as the 

 immediate consequence and the necessary completion 

 of the generally accepted theory of the earth's forma- 

 tion of Kant and Laplace ; and we find therein, in 

 the totality of natural phenomena, such a compelling 

 logical necessity that we must therefore regard this 

 deduction, which to many appears a very bold one, as 

 incontrovertible. ' 



The theory of the earth's formation, of Kant and 

 Laplace, has as ' immediate consequence ' that the 

 life on the earth once began and was not always there, 

 and that is all ; regarding spontaneous generation 

 the theory states nothing. 



Regarding the ' totality of the natural phenomena ' 

 which here comes into question, we can quote, also 

 according to Hertwig's own investigations, the following 

 sentence : ' In the " totality of the natural phenomena " 

 which here actually come into consideration, we find 

 such a compulsive logical necessity that we must regard 

 the denial of spontaneous generation as incontro- 

 vertible/ 



To these ' natural phenomena ' belongs in the first 

 place the experimentally determined fact, accepted 

 by all biologists (' axiom ' as it is often called), that 

 life now only arises from the living. 



To this belongs the ' impossibility ' of regarding 



