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Vries, Hugo de, 1848-1935

"Species and Varieties, Their Origin by Mutation"

Such differences as may be seen in
these cases are therefore never to be considered of value when comparing
two lots of seeds of different origin, or under varying conditions. No
amount of accuracy in the estimation of the results of a trial, or in
the counting out of the several degrees of the anomaly, is adequate to
overcome the inaccuracy resulting from these differences.
It is certainly of great importance to have a correct conception in
regard to the influence of the surrounding conditions on the growth of a
plant and on the development of the attribute we are to deal with. No
less important is the question of the sensibility of the plants to these
factors. Obviously this sensibility must not be expected to remain the
same during the entire life-period, and periods of stronger and of
weaker responses may be discerned.
In the first place it is evident that external or inner influences are
able to change the direction of the development of an organ only so long
as this development is not yet fully finished. In the young flower-bud
of the pistilloid poppy there must evidently be some moment in which it
is definitely decided whether the young stamens will grow out normally
or become metamorphosed into secondary pistils. From this [385] moment
no further change of external conditions is able to produce a
corresponding change in the degree of the anomaly.


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