330 BOTANICAL GAZETTE [May 
ditions of its development, and of the physiological efficiency of these 
factors. 
Recent work of an experimental nature with cultures of isolated 
bog bacteria has shown that the injurious products of the bacterial 
bog flora accumulating in definite layers of the peat substratum are 
the leading factor to be considered in the physiological aridity of the 
local study. The observation was made that a sample of bog water 
in a well-corked glass jar, when kept in the dark at 20-25° C., soon 
shows the formation of methane and other gases, and that in a few 
weeks a thin surface layer becomes noticeable made of up bacteria 
imbedded in a matrix. Exclusion of air prevents further growth of 
aerobs, for in flasks with narrow necks and closed with a cotton plug 
a surface growth is never evident. The breaking down of organic 
matter by bacteria seems to involve, therefore, not only the growth 
and multiplication of the agents of decomposition, but also an accumu- 
lation of by-products which soon decreases the rapidity of aerobic 
bacterial action. Facts to justify the position as to the presence of a 
constituent that imparts an antiseptic action to bog water and bog 
soil are still lacking, but there is sufficient experimental evidence to 
justify the statement that the bacterial flora has the greater share, not 
only in the formation of these toxins, but also in the slow and partial 
decay of bog and swamp plants, that is, in the formation and preserva- 
tion of peat. An attempt has been made to study the physiological 
reaction of the products formed from the activity of single isolated 
species, as well as the effects of the residual products due to mixtures 
of bog bacteria. Without going into too much detail it is sufficient 
to point out here the following: 
From a fresh sample of bog water and bog soil dilution cultures 
were prepared. The isolation of the various species was continued 
upon peat-agar plates, and later in test tubes containing 4 beef- 
broth-agar medium, until from the bacterial colonies which appeared 
upon them, pure cultures were obtained. About 35 different species 
of bacteria have thus far been isolated. The organisms belong for 
the most part to the aerobs. Of the bacteria thus isolated, 21 were 
tested for their toxin-producing power upon a sterilized solution of 
bog water and peat. A number of flasks of a liter capacity containing 
the sterilized solution were then inoculated with the respective pure 
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