60 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, Frith 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. Ina 
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 ‘ Gihrung’ 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 + 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 COs. 
This explanation practically states the fact that cellulose 
and lignin do change into a series of humus compounds, 
and that it isa process of chemical change. It does not 
explain what that change is and why it should take place. 
* Frih. 1. c. 49. 
+ Shaler, N. S. Peat deposits. (16th Rep. Director U. 8. Geol. 
Survey. 4:308. 1895.) 
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