Relations and Transformations of Energy 41 



of very ancient forms that originated amid the ceaseless physi- 

 co-chemical changes of the archsean epoch. They seem, how- 

 ever, to have remained a distinct group and to have given rise 

 to very limited lines of evolutionary advance. 



iVgain, in the nitrogen bacteria still existing, we have types 

 which are capable of fixing loose inorganic nitrogenous com- 

 pounds even in the dark. In presence of such a salt as car- 

 bonate of ammonia the organism oxidizes the nitrogen con- 

 stituent and in the process sets free energy, which is utilized 

 in splitting up the carbon dioxide molecule, the nascent carbon 

 then uniting with other constituents to form elaborate food 

 products. But, in spite of the detailed and fruitful studies of 

 Winogradsky along this line, we are only at the beginning of 

 what will in time constitute important results. These organ- 

 isms, however, seem to represent a second group that have 

 failed to evolve complex organic types. But the possibility 

 of their having primitively been colorless forms, wliich by slow 

 degrees elaborated pigments that might evolve into yellow, 

 yellow-purple, purple-green, blue-green, and green energy- 

 absorbers or transformers, has to be kept in view. Tliis view 

 is favored by all we know at present of the succeeding series. 

 Further, it seems highly fjrobable that from primitive members 

 of this group ancestral animal forms may have been derived. 



A considerable group of rod-shaped bacteria of pink, pink- 

 purple, and purple color has been studied during the past thirty 

 years with great care. These are mainly found, often in great 

 abundance, in marshy or brackish expanses, and at times, as 

 the writer has observed, coloring wide expanses of mud-flats. 

 Engelmann has shown that they can absorb and utilize the 

 dark heat or infra-red rays, and also to a minor degree the 

 yellow rays, through the presence of the contained i)igment. 

 These rays are then utilized for the upbuilding of complex 

 food molecules, but whether the pigment definitely acts as an 

 energy-transformer is still undecided. 



Now, at the present day, in all of the imi)ortant geyser regions 

 the beautiful color of the water and of the siliceous colloid 

 deposits is observed to vary from almost white or pale yellow 



2* 



