HISTORICAL. 25 



the bacteria are fungi which produce putrefac- 

 tion. 



In presence of these opinions, so diverse, as to 

 the nature of the bacteria and their classification, 

 we will finish by saying with Cohn : 



" So long as the makers of microscopes do not 

 place at our disposal much higher powers, and, as 

 far as possible, without immersion, we will find 

 ourselves, in the domain of the bacteria, in the 

 situation of a traveller who wanders in an un- 

 known country at the hour of twilight, at the 

 moment when the Mght of day no longer suffices 

 to enable him clearly to distinguish objects, and 

 when he is conscious that, notwithstanding all his 

 precautions, he is liable to lose his way." 



