368 BOTANICAL GAZETTE [OCTOBER 
The soil used for experiments B, C, and D was a fine sand, which 
has been classified by the Bureau of Soils as Wabash sandy Joam 
This soil was chosen because of its excellent physical condition and 
low organic matter content. 
Sos be 
e 
2 
Z 
3 
: 
Fic. 3.—Representative roots of Christmas pepper plants which received no 
carbon dioxide gas treatments. 
Experiment B 
Head lettuce plants (Lactuca sativa) about 2.5 inches in diameter 
were transplanted into the pots in March 1917 
treatments were started at once. Fig. 6 shows the best of each ol 
the 3 triplicates. 
paw 
Carbon dioxide 
It is noted that carbon dioxide gas appears to 
have benefited the plants receiving treatment. 
These plants 
retained their relative sizes 
until harvested about 3 weeks later. 
