362 THE IRON BACTERIA. 



f active, and turn the substratum brown in a short time (two days), 

 those of Cl. odorifera, on the other hand, retain their chalky-white 

 appearance and evolve the aforesaid earthy smell. RULLMANN (II.) 

 also found that this species is capable of withstanding the influence 

 of drought and poisons, being able to bear exposure for twenty- 

 four hours to a i : 1000 solution of corrosive sublimate. Like its 

 aforesaid congener, Cl. odorifera possesses considerable oxidising 

 power, though this is manifested by the transformation of ammonia 

 into nitric acid, and not by the conversion of ferrous into ferric 

 oxide. This mode of action is not peculiar to this organism alone, 

 but is shared in a still higher degree by a group of bacteria whose 

 acquaintance we shall make in Chapter xxxvi. 



The iron bacteria are not the only Scliizomycetes capable of 

 liberating the energy necessary for the maintenance of their exist- 

 ence from inorganic bodies. In the next two chapters we shall 

 make the acquaintance of fresh natural groups and other processes 

 similar to those described ; thus justifying the title of this con- 

 cluding section. 



