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60
Thus, a doubling of the intensity of assimilation did not appear
until the CO, concentration was increased seven-fold: probably
the light acted as a limiting factor in most of the experiments.
In some experiments with Carpinus Betulus the assimilation at the
beginning rises almost proportionally to the supply of CO,.
14 / EU In more recent days the influence of
i | | ]| the CO, concentration has been exa-
| | mined by Brown and EscowBkE (1902),
|
fö 2
- TT LH TREBOUX (1903) PANTANELLI (1904),
and BLACKMAN and SMITH (1911). Brown
and EscomBe’s experiments are not very
|
| numerous, but they show quite clearly
bil that with a CO, percentage in the air
|
|
of up to 15 times the normal the assi-
milation is approximately directly pro-
portional to the concentration. The ex-
periments of PANTANELLI and of BLACK-
=S fr MAN and SMITH, carried out with water-
| plants (Elodea, Fontinalis), point in the
| | same direction. O. WARBURG’S recently
zm published experiments (1919) with a
| .| Chlorella-like green alga also show an
| approximate proportionality between the
TER addition of CO, and assimilation, with
ve, | lower concentrations. WARBURG’s CO,
[27 ie ie er curve, however, has not the form descri-
2 4 & 8 10 i, bed by Brackman, but is more like the
Fig. 4. Diagram showing the curve for a bimolecular chemical reac-
influence of different CO, supply tion (cp. above, p. 57).
ea neun of My own investigations into the in-
fluence of the CO, concentration upon
the intensity of assimilation show that
the rule »direct proportionality» has here a rather wide applica-
tion. The production of carbohydrates can be multiplied many
times by means of the supply of CO,. The limit for the rise in
the assimilation depends upon the light, and is sometimes reached
— even with a light-intensity of ! at relatively low concentralions
of the carbon dioxide. Further, in accordance with BLACKMAN’S
theory, the limit is in some cases reached suddenly, and with any
Ü
Nasturtium palustre and Viola
tricolor at 1 light.
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