562 FRAGMENTS OF SCIENCE. 



CHAPTER XXXV. 



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 upper mountains. During the 

 early weeks of summer no trace of life is to be discerned in 

 this water; but invariably 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 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 difficulty 

 in believing in cases of spontaneous generation which would 

 now be rejected as monstrous by the most fanatical sup- 

 porter of the doctrine. Shell fish of all kinds were con- 

 sidered to be without parental origin. Eels were supposed 

 to spring spontaneously from the fat ooze of the Nile. 

 Caterpillars were the spontaneous products of the leaves on 

 which they fed; while winged insects, serpents, rats, and 

 mice were all thought capable of being generated without 

 sexual intervention. 



The most copious source of this iife without an 

 ancestry was putrefying flesh; and, lacking the checks 

 imposed by fuller investigation, the conclusion that flesh 

 possesses and exerts this generative power is a natural one. 

 I well remember when a child of ten or twelve seeing a 

 joint of imperfectly salted beef cut into, and coils of mag- 

 gots laid bare within the mass. Without a moment's 



* The Nineteenth Century, January, 1878. 



