This conception leads to an experiment which is the basis of a
practical method much used in France in order to get a higher percentage
of seeds of double-flowering plants.
This method consists in cutting off, in the first place the upper parts
of all the larger spikes, in the second place, the upper third part of
each pod, and lastly all the small and weak twigs. In doing so the
percentage is claimed to go up to 67-70%, and in some instances even
higher. This operation is to be performed as soon as the required number
of flowers have ceased blossoming. All the nutrient materials, destined
for the seeds, are now forced to flow into these relatively few embryos,
and it is clear that [336] they will be far better nourished than if no
operation were made.
In order to control this experiment some breeders have made the
operation on the fruits when ripe, instead of on the young pods, and
have saved the seeds from the upper parts separately. This seed,
produced in abundance, was found to be very poor in double flowers,
containing only some 20-30%. On the contrary the percentage of doubles
in the seed of the lower parts was somewhat augmented, and the average
of both would have given the normal proportion of 50%.
Opposed to the French method is the German practice of cultivating
stocks, as I have seen it used on a very large scale at Erfurt and at
other places.
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