90 LOUIS PASTEUE. 



males and females. To reproduce the species it 

 suffices to pair them.' 



* Scoop out a hole,' said he again, ' in a brick, put 

 into it some sweet basil, crushed, lay a second brick 

 upon the first so that the hole may be perfectly 

 covered. Expose the two bricks to the sun, and at 

 the end of a few days the smell of the sweet basil, 

 acting as a ferment, will change the herb into real 

 scorpions. An Italian naturalist, Kedi, was the first 

 to subject this question of spontaneous generation 

 to a more attentive examination. He showed that 

 maggots in meat are not spontaneously generated, 

 but that they are the larvae of flies' eggs. To prevent 

 the production of maggots, Kedi showed that it was 

 only necessary to surround the meat with fine gauze 

 before exposing it to the air. As no flies could alight 

 upon meat thus protected, there were no eggs de- 

 posited, and consequently neither larvae nor maggots. 

 But at the moment when the doctrine of spontaneous 

 generation began to lose ground by the limitation of 

 its domain, the discovery of the microscope brought 

 to this doctrine new and formidable support. In pre- 

 sence of the world of animalculse, the partisans of 

 spontaneous generation raised a note of triumph. 

 ' We may have been mistaken,' they said, ' as to the 

 origin of 'mice and maggots, but is it possible to 

 believe that microscopic organisms are not the out- 

 come of spontaneous generation ? How can we other- 



