Page:The Scientific Monthly vol. 3.djvu/297

 ORIGIN AND EVOLUTION OF LIFE 291

Nitroso tnonas is found in Europe, Asia, and Africa, while Nitrobacter appears to be almost universally distributed.

���Such bacterial organisms may have flourished on the lifeless earth and prepared both the earth and the waters for the higher forms of plant life. The relation of the nitrifying bacteria to the decomposition of rocks is well summarized by Clarke in the following passage:"

Even forms of life f.o low as the bacteria leem to exert a, defiaite influence in the decom position of roeks. A. Muntz has found the decayed rocks of Alpine ETunmits, where no other life exists?, aivarming with the nitrifying ferment. The limestones and micaceous Fchiats of the Pic du Midi, in the Pyrenees, and the decayed calcareous 3cliist9 of the Faulhorn, in the Bernese Oberland, offer good eiampleB of thia Vind. The orgaoisms draw their nourishment from the nitrogen compounds brought down in ^non and rain ; they convert the ammonia into nitric aciil, and that, in turn, corrodes the caJcHreoua portions of the rocks, A. Stijtzer and K. Hartleb have observed a similar decomposition of cement b; nitrifying bacteria. The effects thus produced at any one point may be small, but in the aggregate they may become appreciable. J. C. Eranner, however, has cast doubts upon the validity of Miintz 's argument, and further investigation of the subject seems to be necessary.

It is notewortliy that it is the nitrogen derived from waters und soils, rather than from the atmosphere, which plays the chief part in the life of these organisms ; in a sense they represent a pre-carbon stage

Clarke, F. W., 1916, p. *85.

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