138 BOTANICAL GAZETTE [AUGUST 
differences in the degree of sensitiveness to toxicity or of the oxidiz- 
ing power of roots are noticeable for the various plants. Phaseolus 
and Vicia jaba proved thus far to be the most plastic plants. In the 
solutions filtered with CaCO, and carbon black the tops surpass in 
Fic, 3.—Corn plants from the various cultures of bog water and bog soil 
Numbers as in the text, p. 133. Four plants from each solution. 
development the growth of roots. The plants show marked vari 
tions in the internal structure of leaf and stem. Those grown the 
bog soil extracts show distinct xerophilous characters. The leaves 
are reduced in area, thicker, of a deeper green, and with revolute 
