THE BACTERIA. 



INTRODUCTION. 



" Corruptio unius est generatio alterius." 



LUCRETIUS, De Rerun, Datura. 



OF all the studies which have for their object 

 the inferior organisms, those which relate to the 

 bacteria offer, without contradiction, the greatest 

 interest, as they touch the most diverse problems, 

 which, it is true, are the most difficult and the 

 least known in biology. The history of these mi- 

 nute organisms is, in truth, related to that of 

 spontaneous generation, to that of the fermenta- 

 tions, to the pathogeny and therapeutics of a great 

 number of virulent and contagious affections, and, 

 in a more general manner, to all the .unknown 

 which, notwithstanding the efforts of modern sci- 

 ence, still surrounds the origin of life and its pres- 

 ervation. 



If the relation of these inferior organisms to 

 the origin of living beings is yet obscure, their 

 role in the preservation of life is better known. 

 It is known that organic matter, once produced 

 and become solid, so to speak, cannot again enter 

 into the general current until it has undergone 



