INTRODUCTION. 7 



Since, then, this is a logical impossibility, it is best 

 to admit the fact and confine our conception of 

 evolution to the realm where there is evidence for it. 

 Now, at the beginning of life there is a break in the 

 series. There is not yet the slightest evidence that 

 living matter could arise from non-living matter. 

 All of the most recent experiments have certified 

 this conclusion. Scientists, perceiving it a logical 

 necessity of these views to believe that life could 

 have arisen from inorganic matter, have had natu- 

 rally a great desire to prove this possibility. The 

 fact that spontaneous generation is universally given 

 up is therefore a testimony to the cogency of 

 the conclusion and the honesty of the investiga- 

 tors. But on the other hand, it is evident enough 

 that while the experiments of Tyndall and others 

 prove that life cannot arises: pontaneously in the 

 conditions under which they have performed their 

 experiments /. e., in closed flasks containing boiled 

 solutions, they by no means prove that spontaneous 

 generation could not have taken place under other 

 different circumstances. We can know nothing as 

 to what may have taken place under different con- 

 ditions. It is equally possible for one side to claim 

 that the experiments teach that life cannot arise 

 spontaneously, and for the other side to claim that 

 while it does not do so now, it might have been 

 possible under very different circumstances in times 

 past. In short, the question is not open to investi- 

 gation. It is impossible to prove that spontaneous 

 generation could never have occurred ; and it is 

 extremely improbable that the opposite view will 



