132 PHYSIOLOGY OF THE BACTERIA. 



be found to occupy the entire field of the micro- 

 scope. From this moment the phenomena which 

 occur differ according to the conditions in which 

 the bacteria are placed. Upon the edge of the 

 air-groove in the moist chamber, the bacteria de- 

 velop very rapidly, forming an interlaced mass ; 

 and in sixteen to eighteen hours, spores may be 

 seen to appear in their interior, — above all, if the 

 preparation has been exposed to light. Often, in 

 this case, the transverse partitions of the filament 

 cannot be seen. If, on the contrary, the bacterium 

 has not been exposed to light, the spores are a 

 longer time in showing themselves (ten or twelve 

 hours more), and almost always division of the 

 filament precedes their formation. In that case, 

 a spore usually appears at each end of the seg- 

 ment in such a manner that the spores belonging 

 to two successive segments are nearer to each 

 other than those in the same segment. Often, 

 also, a spore aborts in a segment (Toussaint). 



We have seen above, in speaking of the res- 

 piration of bacteria, that the same observer has 

 noted in the course of his experiments some phe- 

 nomena proving the evident influence of oxygen 

 upon the development of Bacillus. It is the same 

 for the formation of spores. And upon this point 

 Toussaint makes the very just remark that the 

 phenomena occur in a different manner in culture 

 experiments and in the human organism. In char- 

 bon, the bacteria never form spores. They remain 

 always relatively short, even in the points where 

 they form extra- vascular masses, and where conse- 



