SPONTANEOUS GENERATION.' 



V. 



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 upper mountains. 

 During the early weeks of summer no trace of life 

 is to be discerned in this water ; but invariably to- 

 wards 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 

 rushing 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 informed, I should have found the conclu- 

 sion 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 difiBculty in believing in cases of 

 ' ' The Nineteenth Century,' January 1878. 



