THE TOXIC PROPERTY OF BOG WATER 
AND BOG SOIL 
ALFRED DACHNOWSKI 
(WITH SIX FIGURES) 
The publication of recent work on the existence of injurious sub- 
stances excreted from roots of plants (19, 12, 16,) has necessarily 
resulted in disclosing to ecologists some overlooked data. Repeatedly 
it has been shown that the commonly accepted environmental factors 
are not always sufficient to explain certain important problems of 
association among plants. It must be admitted, therefore, that 
there is a problem to be solved not only regarding the relation of one 
field crop to another, but also with reference to the succession of one 
plant society by another. 
In the study of the structural adaptations of bog plants and the 
causes of their occurrence in bog areas, various theories have been 
brought forward. The idea generally current among workers in the 
ecology of bogs is that the geographical distribution of bogs and the 
local differences in the flora of bog areas and swamps have probably 
come about chiefly through post-glacial migrations and changes in the 
physiography of the habitat. The cause determining the structural 
characteristics of bog plants is generally understood to lie in the 
“physiological dryness” of the habitat. But while some writers lay 
stress upon low temperature of the bog substratum and the presence 
of drying winds as the prominent factors (11, 7, 8), others emphasize 
humous acids in the soil, abundance of soluble salts, and 
(15). More recently the effect has been correlated with low tempera 
ture and lack of aeration of the subsoil rather than with acidity 
(6, 17). 
In 1904, while at work on the ecology of ravines near Ann Arbor, 
Mich., the writer became convinced that the reactions of plants e 
their habitat were equally as great and profound, in some cas if 
the influence of edaphic and climatic factors. In various pce 
decomposed remains of an earlier vegetation led to mechanical 
chemical changes in the soil, the extent of which was more € 
ffective 
Botanical Gazette, vol. 46] [9 
