22 Bergman. — Relation of Aeration to Growth and Activity of 
Table I. 
Gas Content per Litre of Water with and without Philotria. 
No. 
Kind of Water. 
Carbon 
Dioxide. 
Oxygen. 
Nitrogen , 
c.c. 
C.C. 
c.c. 
1 
Standing tap 
2*8 
5*4 
12*6 
2 
>> 
2*6 
5.6 
12*4 
3 
Tap, with Philotria , forenoon 
2*8 
r *4 
12-8 
4 
>> 
2*6 
5'6 
1 2*6 
5 
„ afternoon 
o*6 
8-2 
13-0 
7 
>> »» 
o*8 
7*8 
12*8 
From this it is to be noted that the oxygen and carbon dioxide con- 
tent are not affected by Philotria during the night. During daylight, on 
the other hand, the carbon dioxide is decreased and the oxygen content is 
increased. Accordingly the value of Philotria as a means of aerating 
water is established by these analyses. Other analyses, the figures of 
which are not presented, show that in cloudy weather Philotria has little 
effect on the carbon dioxide or oxygen content. This accounts for the 
wilting noted during cloudy weather in plants with submerged roots in the 
experiments with Impatiens when Philotria was used for aerating the 
water. 
The effect of Philotria in water on the carbon dioxide and oxygen 
content was tried another time. A large glass jar was filled with water and 
a handful of Philotria plants thrown in. The jar was set near a south 
vyindow so as to receive the best possible light. Analyses were made the 
next day. The first analysis was at io.o a.m., the second at n.o a.m., and 
the third at 11.30 a.m. The results are given in the following table : 
Table II. 
Gas Content per Litre of Water with Philotria. 
Sample 
Number . 
Time 
taken. 
Carbon 
Dioxide. 
Oxygen. 
Nitrogen. 
c.c. 
c.c. 
c.c. 
1 
10 a.m. 
i*i 
6*3 
12*2 
2 
10.30 a.m. 
o-8 
7 -o 
12-2 
3 
1 1 a.m. 
o -5 
7*4 
I2‘4 
It is to be noted here also, as in Table I, that the presence of Philotria 
in good light causes a decrease in the amount of carbon dioxide and an 
increase in the amount of oxygen. 
Gas Content of Swamp Water. 
During the summer of 1916, at Hubert, Minnesota, a series of analyses 
of lake and swamp waters was made. The lake water was from Lake 
Hubert near the shore in water about two feet deep. Other samples were 
