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345
sumption of tbe above-mentioned simultaneous exercise of the two
functions of the salts, each being of importance for the growth.
This latter being the case, the straight line indicates that in di-
lute solutions under the conditions of the experiment, both effects
separately vary in the different solutions in such a way that com-
bined they give the same result. — Numerous examples of similar
conclusions in the literature on the subject may perhaps also be
possible’ to interpret on assumption of the combination of both
effects. (Compare the discussion of REEp and others below.)
The experiments described below will give us material for the
discussion of the problem as to which of the two assumptions
given above is the most probable. In choosing sodium as one of
the ions, the effect of which is to be investigated, we have prob-
ably simplified the complicated problem. Because we may per-
haps, — at least for the moment — assume that the nutritive
effect of sodium may be disregarded; cf. OsrEnHovT (1908, p. 337
[15]: “It seems clear that sodium has no nutritive functions in
plants, but only a protective action...“ As sodium has shown
a well marked antagonism to calcium in concentrated solution
(see for example ÖSTERHOUT 1922, p. 127 Table VII [19]) it may be
of importance that the other ion investigated should be calcium.
The combined action — if existing — should therefore consist of a
combination of the antagonistic interference between sodium and
Éaleium. and the nutritive effect of calcium. Besides, as plants
grow without sodium, we are able to get the production eurve
over the isolated variation in the actual amount of calcium. The
comparison of this curve with the production curve over the
variation of the ratio between calcium and sodium, the total con-
centration of the solutions being kept constant, will then give us
a possibility of answering our question with a certain degree of
probability, depending on the particulars of the experiments given
below.
The cultures of the author were carried on for 2 months after
planting, the seeds having been germinated on filter paper and in saw-
dust The culture solution has been continuously renewed, the
fresh solution being supplied through fine capillary tubes at a
constant rate of 50 cc. per plant and day, the old solution being
removed through overflow. A high acidity of the solution was
desirable, as precipitated phosphates easily block the capillary
tubes. With regard to this Svalól’s Dala-oats, pure line, 0924 was
23 — 24285. Svensk Botanisk Tidskrift. 1924.
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