THE VITAL PHENOMENA OF BACTERIA. I 1 1 



Winogradsky has discovered that there are 

 other sources of energy besides the sun's 

 rays and the oxidation of ammonia which are 

 available for purposes of organic synthesis. 

 He found that the iron bacteria, Crenothrix 

 and Leptothrix ochracea, which sometimes 

 bring about the dreaded " water calamity " 

 as, for example, that in the Berlin supply from 

 Lake Tegel can obtain their energy by oxi- 

 dation of ferrous compounds to ferric com- 

 pounds, as e. g. from ferrous carbonate to ferric 

 hydroxide : 2 FeCO 3 + 3H 2 O+O = Fe 2 (OH) 6 + 

 2CO 2 . The presence of iron in the sheath of 

 Crenothrix had been previously recognized by 

 Zopf as a phenomenon probably of significance 

 to the life of the bacterium. In this way the 

 iron algae and the iron bacteria share in the 

 formation of the phosphates and silicates of 

 iron deposited in the old morasses, and, from 

 this point of view, they belong to those mi- 

 crobes concerned in rock-formation and the 

 building up of the earth's crust. 



The Beggiatoa or sulphur bacteria, some of 

 which are devoid of pigment and some colored 

 by bacterio-purpurin, are able to obtain their 

 energy through the oxidation of sulphuretted 

 hydrogen and then of the sulphur grains thus 

 formed to sulphuric acid. To this oxidative 

 process maybe due the appearance of the sul- 



