DACHNOWSKI: BOG VEGETATION AND PEAT SOILS 59 
assimilated by plants. The presence of one substance or the 
concentration of another constituent as determined by quantita- 
tive analysis may have only an apparent relation but not neces- 
sarily a causal value. This might be for the reason that the sub- 
stances are differently distributed on account of differences in 
solubility or oxidation, are absent in one phase of the decom- 
position process because of differences in the bacterial flora at 
work in different layers, or vary greatly with reference to the 
diosmotic properties of the absorbing organs of plants. Humus 
has long been recognized as a very important factor in soil fer- 
tility, and yet almost all the difficulties in any special problem with 
humus or peat arise in the lack of knowledge of the chemical 
nature and the effects on plant life of the various organic com- 
pounds resulting from weathering processes and from the activity 
of microorganisms. The complexity of the problem emphasizes 
the need of physiological studies. The bacteriological-chemical 
and the physiological analyses deserve on that account a closer 
consideration. The writer’s method of determining the trans- 
formation products in various media inoculated with bog bacteria 
should possess the exactness and reliability necessary for the solu- 
tion of this problem. The determination of these bodies by 
chemical means alone will be only in part of value for investiga- 
tions in ecology. 
Numerous problems of experimentation have arisen quite apart 
from the main question itself. 
It would be interesting to determine the water requirement of 
bog plants for a growing period and to compile the results on a 
basis of the water needed for one part of ash yielded. Data on 
the specific differences in the ratio, i. e., on the water requirements 
of bog plants and the percentage of ash in herbs, shrubs, and trees 
covering peaty basins, are not at hand. The analyses reported by 
C.S. Sargent in the ninth Census of the forest trees of North America 
give the percentages for some of the trees common to bogs. The 
data are interesting in showing that the majority of trees fre- 
quenting bogs have a percentage of ash less than 0.5, and only a 
few of the deciduous species occurring on Ohio peat deposits have a 
percentage of ash as high as 1.5. Comparisons of the quantities 
of mineral salts contained in peat deposits, differing so widely in 
