368 BOTANICAL GAZETTE [NOVEMBER 



Aside from the mineral substances composing the ash of such 

 bodies, the organic compounds are made up for the most part of 

 carbon, hydrogen, and oxygen. In the case of the proteids, there 

 are added to these nitrogen, sulfur, and phosphorus. As to the 

 exact nature of the compounds existing in the dead material, aside 

 from the carbohydrates, very little is known. The same statement 

 holds as to the nature of the decomposition which goes on without 

 the intervention of saprophytic organisms. But it seems probable 

 that oxidation does occur. This action, then, is the beginning of 

 the more comprehensive process known as peat formation. 



When plants or their organs die, under ordinary circumstances they 

 are at once attacked by fungi and bacteria. The progress of disso- 

 lution is then greatly hastened, and the final disintegration is more 

 complete. According to the operation of certain external factors, 

 the destruction may involve two very different groups of organisms 

 and result in bodies of very different chemical and physical properties. 

 These two processes are known as eremacausis and putrefaction 



(61, 39)- 



Where access to oxygen is accompanied by favorable temperature 

 and moisture conditions, the first of these processes, eremacausis, 

 takes place. The formation of ordinary soil humus may be cited as 

 an example. That oxygen plays the important role has been demon- 

 strated both by experiment, and by the analysis of the gaseous and 

 solid products. It has been shown, for example, that soils in which 

 eremacausis is in progress contain CO 2 and O in inverse proportion 

 to one another. Under constant volume, as the one increases the 

 other decreases. It has been also shown by experiment that the 

 process is wholly dependent upon the activities of certain lower 

 plants. Among these members of the genera Mucor, Aspergillus, 

 Penicillium, Saccharomyces, Micrococcus, Bacterium, Spirillum, 

 Crenothrix, and Beggiatoa are most important. 



The carbohydrates are by this means broken down to CO 2 and 

 H 2 O. The albuminoids and amides constitute the principal forms 

 of the nitrogenous materials. Under the influence of these organisms, 

 especially their katabolic processes, the oxygen unites with the carbon 

 to form CO 2 , the S is oxidized to H 2 SO 4 , the P to H 3 PO 4 , and the 

 H to H 2 O. The first form in which the nitrogen reappears is that 



