XIII 



SPONTANEOUS GENERATION ' 



WITHIN ten minutes' walk of a little cottage which 

 I have recently built in the Alps, there is a 

 small lake, fed by the melted snows of the up- 

 per mountains. During the early weeks of summer no 

 trace of life is to be discerned in this water; but invari- 

 ably toward the end of July, or the beginning of August, 

 swarms of tailed organisms are seen enjoying the sun's 

 warmth along the shallow margins of the lake, and rush 

 ing with audible patter into deeper water at the approach 

 of danger. The origin of this periodic crowd of living 

 things is by no means obvious. For years I had never 

 noticed in the lake either an adult frog, or the smallest 

 fragment of frog spawn; so that, were I not otherwise in- 

 formed, I should have found the conclusion of Mathiole 

 a natural one, namely, that tadpoles are generated in lake 

 mud by the vivifying action of the sun. 



The checks which experience alone can furnish being 

 absent, the spontaneous generation of creatures quite as 

 high as the frog in the scale of being was assumed for 

 ages to be a fact. Here, as elsewhere, the dominant mind 

 of Aristotle stamped its notions on the world at large. 

 For nearly twenty centuries after him men found no diffi- 

 culty in believing in cases of spontaneous generation which 



1 "The Nineteenth Century," January, 18T8. 



(306) 



