1918] NOYES, TROST, & YODER—ROOT VARIATIONS 360 
Fig. 7 shows the roots from the 2 most representative of each set 
of 3 plants grown under the different treatments. Carbon dioxide 
has affected the roots of these plants, although not to the 
extent that it did those of the Christmas peppers. 
— 
1 
Root deve 
a 
& 
. 
: 
B 
3 
© 
s 
g 
5 
B 
t 
Fic. 4.—Representative roots of Christmas pepper plants which received 8 hours’ 
treatment of carbon dioxide daily 
opment departs from normal with increased carbon dioxide appli- 
cations. 
Experiment C 
Radishes (Raphanus sativus) of the variety “Rapid Red” were 
sown in Wagner pots in March 1917. None of the plants were 
disturbed after the seed was sown. At the time of harvest the 
series of plants receiving no carbon dioxide gas applications had 
straight tap roots, while the roots of those receiving the gas showed 
