The Relation of Aeration to the Growth and Activity 
of Roots and its Influence on the Ecesis of Plants 
in Swamps . 1 
BY 
H. F. BERGMAN. 
With three Graphs in the Text. 
T HE effect of various factors on the form and growth of roots has been 
repeatedly investigated by experimenters during the past fifty years, 
although little attention seems to have been paid to the effect of the sur- 
rounding medium on their functional activity. This is particularly true 
with reference to their oxygen supply. Very recently, however, Livingston 
and Free (14, p. 182) have shown that £ the first effect of oxygen deprivation 
is an interference with the absorption of water by the roots \ Accordingly, 
in determining the effect of various factors on the growth and distribution 
of swamp plants, it was decided to make a special study of aeration in such 
habitats. In so far as possible, exact data have been secured as to the 
oxygen and carbon dioxide content of lake and swamp waters under normal 
conditions. The influence of other factors, however, has not been neglected. 
The work was in progress about three years. The field work was done 
mostly during the summer months in the northern part of Minnesota. The 
experimental work was carried on during the winters of 19 14-15 and 
1915-16 in the University greenhouse* 
Effects of Aeration on Submerged Roots. 
Experiments with a number of plants have been performed in the 
greenhouse to determine the effect of root submergence, through limitation 
of the air supply, as a factor in the development and activity of roots. In 
the course of these experiments the plants were grown in the same kinds 
of soil and under the same conditions of temperature. The kind of water 
or amount of air supplied were the only factors varied. 
Seedlings of bean ( Phaseolus vulgaris var.), plants of Impatiens balsa - 
mma , Pelargo 7 iium sp., Cyperus alter nifolius, Ranunculus abortivus and 
1 Accepted by the University of Minnesota in partial fulfilment of the requirements for the 
Degree of Doctor of Philosophy. 
[Annals of Botany, Vol. XXXIV. No. CXXXlII. January, 1920.] 
