VIII, C, 1 
Brown: Growth of Elodea 
17 
against the substratum by small glass rods so that the plants 
could become rooted. In the other jars they were allowed to 
float at the surface. CO, from a generator was passed through 
the water in all of the jars for from ten to fifteen minutes several 
times each day. At the same time another series was pre- 
pared which was similar to this except that no CO., was passed 
through the water. The growth of the plants for a period of 
twenty days in the series in which CO, was added to the water is 
given in Table IX, and the growth of the plants in the other 
series for the same period in Table X. These two tables are 
summarized in Table XI. 
Table IX.— Growth of Elodea in water to which CO2 was added. 
No. of plant. 
Growth- 
Rooted 
in soil. 
1 
2. 
J 
8 
4 
6. 
6. 
7. 
8. 
9. 
10. 
Total . . _ 
Averag-e 
Cm. 
15.5 
11.2 
13.7 
13.1 
13.1 
13.1 
12.3 
12.2 
.16,3 
11.5 
Rooted 
in sand. 
Floating Floating 
over soil, over sand. 
132.0 
13.2 
Cm. 
12.8 
14.8 
12.7 
12.6 
15.8 
14.2 
17.6 
17.4 
13.0 
9.7 
Cm. 
13.4 
13.0 
16.4 
13.5 
13.9 
13.8 
12.6 
13.4 
14.8 
13.5 
140.6 
14.1 
138.3 
13.8 
Cm. 
11.1 
15.4 
19.6 
12.1 
15.1 
13.9 
15.1 
14.0 
9.9 
16.9 
143.1 
14.3 
Table X.~Growth of Elodea in water to which CO. was not added, 
No. of plant. 
Rooted in'Rooted in Floatinj? Floating 
soil. 
sand. 
S 
4 
over soil, over sand, 
6 
7. 
8. 
8. 
10, 
ToUl .„, 
Average . 
114854 
