128 PHYSIOLOGY OF THE BACTERIA. 



Cohn, who had in his first publications refused 

 to the bacteria the property of reproduction by 

 spores, thinking that the facts observed by Hoff- 

 mann related to different beings, has verified the 

 experiments of Koch upon the development of 

 B. anthracis, and has himself demonstrated sim- 

 ilar phenomena in B. subtilis. 



In culture experiments made with infusion of 

 hay, we see, at a certain moment, in the homo- 

 geneous filaments of the Bacilli very refractive 

 corpuscles making their appearance. Each of 

 them becomes a spore, oblong or in the form 

 of a short filament, highly refractive, and with 

 well-defined outlines. We find the spores ar- 

 ranged in a simple series in the filaments. As 

 soon as the formation of spores has terminated, 

 the filaments can generally no longer be distin- 

 guished, and one would say that the spores were 

 completely free in the mucus ; but their linear 

 arrangement shows always that they are produced 

 in the interior of filaments. Little by little these 

 dissolve, being reduced to a fine powder ; and the 

 spores fall to the bottom of the liquid, where they 

 are found in abundance. The germination of the 

 spore does not seem to occur in the same medium ; 

 but if we take a spore from the deposit formed in 

 an infusion of boiled hay, and transport it into a 

 new infusion, we see the spore swell up, and a short 

 tube form itself at one of its extremities : at this 

 moment it resembles a bacterium with a head. 

 Soon the very refractive body disappears, the tube 

 stretches out into a short rod of Bacillus, com- 



