372 BOTANICAL GAZETTE [NOVEMBER 
substratum to disintegration, and favors the carrying away of the 
products of decomposition; in general, it favors eremacausis. In 
the samples of water which I have examined at various times from 
the same depressions, there have been marked variations within short 
periods of time in the color of the water and in the presence of such 
animals as Daphnia and Cyclops. No attempt has been made to 
count or even separate the bacteria present, but it is probable that 
_ they too vary with the color of the water and the animal life. 
When the bog land has been cleared and ditched, the marked 
increase in the rate of decay is apparent. Eremacausis becomes 
exceedingly active, and in the course of a few years the substratum 
is reduced to a brownish-black, pulp-like mass. If continued, this 
goes to form “muck,” a substance which when dry is powdery and 
somewhat resembles soot. During these processes of decay there 
occurs a succession among the organisms present. The accumulation 
of disintegration products makes the medium unfavorable for the com- 
tinued existence of the organism involved in their production. At the 
same time it may furnish optimum conditions for the development of 
other forms. An acid medium favors the growth of the Phycomycetes, 
while alkalinity favors the bacteria. In such regions as this, were 
the underground waters are alkaline, the latter fact, together with 
fluctuations in the ground-water level, may have an important bearing 
upon the presence of more thoroughly decayed peat and of a distinct 
depression about the margins of many of the bogs. weal 
If to the factors of relative scarcity of oxygen and the acidity : 
the soil solution is added the occurrence of temperatures considerably 
lower than those of the surrounding uplands, it is not di eo 
understand why a large part of each year’s vegetative products sho 
escape complete destruction. In our estimate of the bog . 
as a habitat for higher plants, the strong competition with them of 
scopic plants to which the former are subject in the acquisition 
oxygen for their underground parts, must be emphasized. 
THE PHYSICAL AND CHEMICAL PROPERTIES OF ie a 
The peat formed through the agency of the bog << eee 
attendant plants has a fibrous and matted appearance. a put slight 
of the various dead stems, roots, and leaves have suffer 
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