26 THE ORIGIN OF LIFE 



we are attempting to explain. After the fiery earth 

 had so far cooled that its outermost layer had hard- 

 ened to a firm crust, and after water had condensed 

 to a liquid form, there could at first only have been 

 inorganic substances in existence. In order to prove 

 spontaneous generation, therefore, it would be neces- 

 sary to try to find out from what mingling of in- 

 organic combinations organisms could arise ; to prove 

 that spontaneous generation could never have been 

 possible is out of the question. ... It would be im- 

 possible to prove by experiment that spontaneous 

 generation could never have taken place ; because each 

 negative experiment would only prove life does not 

 arise under the conditions of the experiment. But 

 this by no means excludes the possibility that it might 

 arise under other conditions. 



Haeckel is no less emphatic in his repudiation 

 of the too wide and positive nature of the con- 

 clusions drawn by Pasteur and others from the 

 results of their experiments with organic in- 

 fusions. In his work The Wonders of Life he 

 says : * 



These experiments prove nothing whatever beyond 

 the fact that new organisms are not formed in certain 

 infusions of organic matter under definite artificial 

 conditions. They do not even touch the important 



1 Translation, 1904, p. 367. 



