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 con- 

 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, where 

 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. 



If to the factors of relative scarcity of oxygen and the acidity of 

 the soil solution is added the occurrence of temperatures considerably 

 lower than those of the surrounding uplands, it is not difficult to 

 understand why a large part of each year's vegetative products should 

 escape complete destruction. In our estimate of the bog substratum 

 as a habitat for higher plants, the strong competition with the micro- 

 scopic plants to which the former are subject in the acquisition of 

 oxygen for their underground parts, must be emphasized. 



THE PHYSICAL AND CHEMICAL PROPERTIES OF PEAT. 



The peat formed through the agency of the bog sedges and their 

 attendant plants has a fibrous and matted appearance. The structures 

 of the various dead stems, roots, and leaves have suffered but slight 



