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361
quence of caleium-starvation. This may be very possible, though
it may be also due to the lack of balance in a Hoagland’s-solution,
if calcium is replaced by another ion. At any rate it is very
probable that we must reckon with a starvation of caleium in
these cases. This need, however, not be the only cause of the
harmful effect of solutions lacking in calcium. In fact the dif-
ference in the dry-weights obtained in the ratios 100 Na:0 Ca
and 98 Na:2 Ca in the experiment with Citrus limonia are pro-
bably too great in relation to the maximal dry-weight of the
series to be caused by the nutritive effect of 0.00008 mol CaCl,
alone, and thus an antagonizing effect also here very probably
combines with the nutritive one. The deviating result of the 23
days experiment, recorded in Reep’s table III, may indicate a
straight line, i. e. the same curve as has been discussed above (p. 344).
— Thus the investigations of Reep and BREAZEALE and REED and
Haas do not contradict the opinion given in this paper, even if
they do not furnish any safe support for this opinion.
The reason why workers, dealing specially with antagonism in
dilute solutions, have not even ‘discussed the possibility of a
simultaneous exercise of both functions, is probably due to the
fact that their results, having been obtained from experiments with
a comparatively short time of growth, do not show any well marked
differences for different ratios. Furthermore the old opinion given
in the “minimum-law“, that only one factor is of influence upon
the production of dry-substance, may have been of influence, as well
as the fact that the chief opponent against this law, —MITSCHERLICH —
has not taken into consideration the retarding effect which a
factor has upon the growth, his logarithmical approximation of
the production curve agreeing with the actual values of his expe-
riments only for factor-intensity-values lower than the optimal
intensity. The importance of retarding factors for the production
curve has been pointed out by Rırper. (1922, [23], p. 34—37), who
is of the opinion that the retarding influence is operative from
the beginning of the production curve. Bonporrr (1923 [5], p.144;
cf. also SAPÉHIN, 1924, [25] p. 388) gives an analytical expression
lor a production curve, taking into consideration this retarding
influence, and thus obtains a curve which agrees approximately
with the production curve also for super-optimal intensities of the
production factor. Against this, ROMELL (1924, [24] p. 93) observes
that the term of the retarding effect in Bonporrr’s function in
94 — 24285. Svensk Botanisk Tidskrift. 1924.
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