EVOLUTION AND CLASSIFICATION OF BACTERIA 449 



he assumes that the primordial organisms must have Hved in 

 darkness and have depended upon inorganic matter for nutrition 

 and energy. He overlooks the fact that if the earliest protoplasm 

 possessed any such valuable property as the ability to utilize the 

 chemical energy of inorganic material, it is strange that all but a 

 very few of the organisms found today should have lost the power. 

 He does not mention the idea that autotrophism may be a spe- 

 cialization developed by bacteria later on in the course of evolu- 

 tion; and yet the very organism which he selects as probably 

 the most primitive of autotrophic bacteria, B. methanicus Sohngen 

 (renamed Methanomonas by Jensen), derives its energy from 

 methane liberated in swamps from decomposing organic matter. 

 In other words, it gets its energy indirectly — through other 

 organic agencies — from sunlight. Jensen's claim that under 

 primordial conditions it utilized methane produced by volcanic 

 action is a rather improbable assumption. It might be possible 

 to advance more valid arguments in favor of the greater primi- 

 tiveness of the nitrifying bacteria. Jensen does not deny this 

 possibility; but he plainly believes that the most primitive 

 organism is to bo found among the autotrophic bacteria. 



The committee on classification has apparently accepted this 

 argument of Jensen's, as seen by a glance at the genera composing 

 the family Nitrobacteriaceae. The first seven genera of Nitro- 

 bacteriaceae listed by the committee are the same and are even 

 arranged in the same order as the seven genera placed by Jensen 

 in his most primitive family, the Oxydobacteriaceae, except 

 that for three of the genera the committee has recognized the 

 validity of names prior to those of Jensen. It is evident that if 

 the society adopts the committee report, it will be committing 

 itself as favoring Jensen's arguments, and before doing this it 

 is necessary to be sure that there are no other equally tenable 

 theories as to primordial life. 



As a matter of fact, other theories have been advanced which 

 are by no means disproved by Jensen's arguments. Most 

 important of them is the one that looks to the blue-green 

 algae or to the little known phototrophic pigment-containing 

 bacteria as the primordial organisms. These organisms, like 



THE JOURNAL OF BACTERIOLOGY, VOL. Ill, NO. 5 



