VIII, C, 1 
Broivn: Groivth 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 XL 
Table IX. — Growth of Elodea in water to which CO- was added. 
Growth — 
No. of plant. 
Rooted 
in soil. 
Rooted 
in sand. 
Floating 
over soil. 
Floating 
over sand. 
1 
Cm. 
15.5 
Cm. 
12.8 
Cm. 
13.4 
Cm. 
11.1 
2 
11.2 
14.8 
13.0 
15.4 
3 
13.7 
12.7 
16.4 
19.6 
4 
13.1 
12.6 
13.5 
12.1 
1 5 
13.1 
1,5.8 
13.9 
15.1 
6 
13.1 
14.2 
13.8 
13.9 
7 
12.3 
17.6 
12.6 
15.1 
8 
12.2 
17.4 
13.4 
14.0 
9 
16.3 
13.0 
14.8 
9.9 
10 
11.5 
9.7 
13.5 
16.9 
j Total 
132.0 
140.6 
138.3 
143.1 
Average.. ... 
13.2 
14.1 
13.8 
14.3 1 
Table X. — Growth of Elodea in water to which CO- laas not added. 
Growth — 
i 
1 No. of plant. 
1 
Rooted in 
soil. 
Rooted in 
sand. 
Floating [ 
over soil. 
Floating 
over sand. 
Cm. 
C)ii. 
5.5 
Cm. 
5.3 
Cm. 
4.3 
1 2 . 
3.4 
0.5 
3. 1 
6.9 
! 3 
4.0 
3.1 
6.5 
5.5 
1 4 
2.5 . 
1 2.5 
7.8 
6.7 
i 5 . 
1.7 
3.7 
5.9 
9.3 
! 6 
3.8 
2.1 
3.2 
8.5 
7 
2.9 
3.7 
4.0 
3.2 
8 
4.8 
4.5 
6.1 
0.4 
I 9... 
3.6 
3.0 
2.7 
5.3 
' 10 
2.8 
2.6 
6.1 
5.4 
‘ Total 
31.3 
31.2 
i 50.7 
55. 5 
Average ... . 
3. 13 
3. 12 
5. 07 
1 
5. 55 
114854 2 
