MISSOURI BOTANICAL GARDEN. 



The first process is brought about " through the direct in- 

 fluence of the plasma of a living fungus, and is characterized 

 by an evolution of heat and carbon dioxide . The other form is 

 caused by a ferment excreted by living plants. This distinc- 

 tion can no longer be made to-day, as it seems probable that 

 the first form of decomposition is also due to a ferment. 

 Since humification takes place only under water, Friih holds 

 that one might suppose a ferment the active agent in the for- 

 mation of peat. But this cannot be true, for, if a ferment 

 were the agent forming peat from vegetable substances, the 

 process of humification would be a uniform one, that is, a 

 given mass would be entirely transformed into peat. In a 

 bog, however, this is not the case, for there are alternate 

 layers, some of which are humified, others not. Friih, 

 therefore, agrees with Einhof who says that " lack of free 

 oxygen, a high degree of moisture and a low temperature, 

 brought about by much moisture, bring about a decompo- 

 sition of a peculiar kind, i. e., the formation of humus 

 compounds or peat." He sums up as follows:* ' The 

 formation of peat is neither due to ' Gahrung ' nor to a fer- 

 ment but consists in the slow decomposition of plants, with 

 the greatest possible exclusion of oxygen by water, and at 

 low temperature. Bacteria have nothing to do with the 

 formation of peat." This view of peat formation is the 

 one generally accepted; thus, Shaler f explains it as 

 due to the arrest of disintegration arising from the fact 

 that the oxygen of the air does not have free contact with 

 the carbon, and thus cannot convert it into CO2. 



This explanation practically states the fact that cellulose 

 and lignin do change into a series of humus compounds, 

 and that it is a process of chemical change. It does not 

 explain what that change is and why it should take place. 



* Friih. 1. c. 49. 



t Staler, N. S. Peat deposits. (16th Rep. Director U. S. Geol. 

 Survey. 4:308. 1895.) 



38 



