126 PHYSIOLOGY OF THE BACTERIA. 



cation being continued with the same conditions, 

 the bacteria issuing from a single germ would fill 

 the ocean in five days." 



Reproduction by Spores. — The multiplication 

 by fission, known to the earliest microscopists, has 

 been until recently the only mode of propagation 

 admitted by the authors. Thus M. de Lanessan, 

 in the excellent article which he has devoted to 

 the bacteria, says that the marvellous resources of 

 modern science have not yet permitted us to rec- 

 ognize any other mode of propagation for these 

 organisms. 



However, M. Ch. Robin had already, in 1853, 

 indicated the presence in Leptothrix buccalis of 

 little round bodies, " which are perhaps spores." 

 Pasteur has since, in 1865, recognized that " the 

 vibrios of putrefaction and of butyric fermentation 

 present a sort of ovule, or ovoid corpuscle, which 

 refracts light strongly, either in the extremity 

 or in the body of the articles." Later, the same 

 savant, more explicitly, says clearly that these or- 

 ganisms have two modes of reproduction, — by 

 fission and by interior spores (" noyaux "). 



Towards the same epoch, Hoffmann also pointed 

 out a reproduction by free cellular formation in 

 some bacteria. But we must come to the labors 

 of Cohn, Billroth, and Koch, in order to find pre- 

 cise observations in this regard. 



The formation of spores has been observed 

 in Bacillus subtilis by Cohn, Bacillus anthracis 

 by Koch, and in Bacillus Amylobdcter by Van 

 Tieghem. 



