XII, c, 2 Brown and Heise: Carbon Dioxide Assimilation 89 
eine angenaherte Proportionalitat zwischen Lichtstarke und der ausges- 
chiedenen Sauerstoffmenge durch die Athmung in ahnlichem Sinne besei- 
tigt werden. 
One of the most widely quoted researches on photosynthesis 
is that of Pantanelli,(l6) who also worked on Elodea with a 
bubble-counting method. 
Pantanelli’s results on this subject are perhaps best expressed 
in his figure a, obtained with a carbon dioxide concentration of 
1 to 15 volume per cent. We have shown in Table III all the 
readings given by him in curve a for assimilation velocities with 
different light intensities up to full sunlight. In order to make 
Pantanelli’s results comparable with those of other workers, 
we have reduced his readings from the number of seconds re- 
quired for the evolution of ten bubbles to the number of bubbles 
evolved in ten seconds. 
Table III. — Carbon dioxide assimilation and light intensity (Pantanelli 
on Elodea). 
[Curve (o) 1-16 volume per cent COa.] 
Series. 
Light intensity (di- 
rect 8unlight=l). 
Initial value. 
After ten minutes exposure. 
Frac- 
tion. 
Decimal. 
Time required for 
10 bubbles. 
1 
1 
I Number of bub- 
1 bles in 10 seconds. 
i 
Increase in num- 
ber of bubbles 
per unit of 0.01 
direct sunlight. 1 
Time required for 
10 bubbles. 
Number of bub- 
bles in 10 seconds. 
Increase in num- 
ber of bubbles 
per unit of 0.01 
direct sunlight. 
Seconds. 
Seconds. 
0.028 
33.2 
3.06 
1. 09 
35.3 
2.83 
1.01 
0.040 
21.0 
4.76 
1.40 
22.0 
4. 55 
1.41 
I. AscendinB 
0.066 
16.0 
6.66 
0.71 
16.0 
6.25 
0. 63 
i 
0. Ill 
12.3 
8.13 
0.33 
13.3 
7.60 
0.30 
i 
0. 260 
9.6? 
10. 4? 
0. 16 
(?) 
i 
1.000 
7.7 
13.0 
0.03 
8.6 
11.8 
0.01 
aV 
0.028 
36.3 
2.83 
1.01 
33.2 
3.05 
1.09 
aV 
0.040 
26.0 
3.85 
0. 83 
24.7 
4.05 
0.82 
II. Descending 
0.066 
19.3 
6.2 
0.60 
18.0 
6. 65 
0.56 
i 
0.111 
16.1 
6.6 
0.31 
13.9 
7.2 
0. 37 
i 
0. 250 
8.6 
11.8 
0. 37 
i 
1.000 
7.0? 
14.3 
0.03 
As in Reinke’s work, (18) the first augmentation of the rate 
of bubble emission is in some cases proportionately greater than 
that of light. Again the results show not a direct proportion- 
ality between assimilation and light intensity, but a progres- 
sively smaller relative increase in assimilation with increasing 
illumination. 
147918 Z 
