THE EXCHANGE OF IONS 
265 
X io~^ solution of CaS04 was reduced in concentration through 
absorption to a Httle over 12M X io~^, and provided four lupine 
2 3 
Fig. 2. Curves showing the changes in concentration of the Ca(N03)2 solutions 
used in experiment 2. 
Fig. 3. Curves showing the changes in concentration of the CaS04 solutions 
used in experiment 3. 
seedlings with all the CaS04 which they were able to absorb during 
their short life in the dark. In the cultures which offered an increased 
