: 
5 
| 
A 
4 
a eae es 
192 MISSOURI BOTANICAL GARDEN. 
oxygen produced by the fall growth of diatoms and grass- 
_ greens. After the thick ice sheet was formed about mid- 
December there was but little change. The oxygen and 
carbon-dioxide figures both seek the medium and remain 
there quite constantly. There is but little live vegetation 
under the ice, and what is there cannot be very active. The 
same must be true of any animal life that may be present. 
The column showing the per cent of saturation and oxygen 
shows a more striking contrast than the column of cc., which 
strongly indicates that it must be due to biological rather than 
to meteorological influences. This is more strikingly shown 
in the graph showing per cent. of saturation. 
GRAPH II. 
150 150 
140 140 
130 \ 130 
120 “a | \ 120 
18 / 110 
MOLVA ALL UNECE, - 
LL A SN : 
me VIM INIT | \ 
80 |\ 80 
* NC IN \ . 
60 MV | | | 60 
| \ 
50 \ ] \ 50 
40 Y 40 
30 0 
20 20 
10 10 
JUNE | JULY | August |septemBer | ocTOBER | NOVEMBER| DEC. r 
ms Senet Graph showing percentage of saturation of oxygen. 
EXPERIMENTATION IN LABORATORY— 
GENERAL. 
In attempting to arrange a set of experiments under control 
conditions to show on a small scale the effect of an increase 
or decrease of the two gases, oxygen and COs, a plan was hit 
