38 Causes and Course of Organic Evolution 



and natural syntheses of organic compounds, from the ener- 

 gizing standpoint. 



In view, nevertheless, of accomplished results it seems almost 

 assured that investigation will gradually solve for us the prob- 

 lems: (1) what energy transformer or transformers have been 

 evolved, for use in the evolving cell; (2) what equilibrated 

 combination of diverse colloid molecules can regenerate or 

 sustain themselves and also act as synthesizers of added food; 

 (3) what colloid bodies can effect transformation or digestion 

 of food materials without themselves undergoing great decom- 

 positions? 



To each of these we can give as yet only very imperfect 

 reply. But a partial — even if slight — answer may be got by 

 study of some simple living organisms, and to these we shall 

 now turn. 



Did we think only of the mode of nutrition pursued at the 

 present day by green plants and by animals, it might be con- 

 sidered that all organisms have originated from a monophyletic 

 ancestry, in which by formation of a primitive and later of a 

 specialized pigment, chlorophyll, the earlier process of food 

 formation took place, through elaboration of the simpler car- 

 bohydrates, such as sugar. But results of the past quarter 

 century have fundamentally modified our conceptions. 



Amongst the Acaryophyta (p. 51) or Protobiota at present 

 existing, those forms which have been termed the sulphur 

 bacteria, the nitrogen bacteria, and the iron bacteria seem all 

 to derive food products or stores of energy, not through the 

 intervention of chlorophyll, but by direct utilization of con- 

 stituents of various inorganic salts dissolved in water. In 

 other words, all evidence points to the conclusion that they 

 can form complex organic molecules from simple inorganic 

 salts in solution, and that the energy needed for the life of each 

 organism is obtained from some salt absorbed. Furthermore, 

 it is highly important to note that such work can be performed 

 perfectly, as by Beggiatoa, in the dark, since it utilizes not 

 sunlight but sulphur compounds as an internal source of energy. 



True, this still leaves us far removed from an exact knowledge 

 as to how inorganic or — if we may use such an expression — 



