366 BOTANICAL GAZETTE [OCTOBER 
dioxide gas added in equal amounts and in the same manner to all 
pots receiving gas treatments. 
Equal weights of thoroughly mixed soil were put in paraifined 
Wagner pots of the most approved type (fig. 1). The soil in all 
pots was compacted by dropping each pot on the cement floor an 
equal number of times. Distilled water was added through the 
tubes to bring the moisture content up to one-half saturation, 
where it was kept by successive 
oS additions of water throughout the 
Bg EEE, periods of investigation. The 
relative position of. the pots was 
changed at regular intervals to 
: correct differences in exposure and 
temperature in the greenhouse. 
Experiment A 
The. Christmas pepper (Caps7- 
cum annuum abbreviatum) was the 
first plant used. Plants were 
started in November 1915 in the 
greenhouse from seed, and trans- 
planted February 1 into the 
Wagner pots. The soil used was 
Sioux silt loam. The plants were 
about 1.5 inches high and carbon 
dioxide treatments were commenced after the plants became estab- 
lished. Three pots containing 4 plants each received no applications 
of carbon dioxide, 3 others received carbon dioxide applications 
8 hours each day, and yet another set of 3 pots received carbon 
dioxide applications constantly. The gas was applied at the rate 
of approximately 650 cc. per hour, and fig. 2 shows the method 
of getting the gas from the pipe line to the individual pot. The 
wash bottles served as a means of equalizing the flow of gas 
into each pot. Fig. 2 shows the Christmas pepper plants after 4 
months’ treatment. At first the carbon dioxide treatment retarded 
growth, but by the time the picture was taken there was no great 
difference in size between the treated and untreated plants. Fig. 3 
Fic. 1.—Wagner pot ysieey sub- 
irrigation tubes in place 
