Since it is an annual plant, only the seeds are for
sale, and this at once gives a sufficient proof of its heredity. In all
cases, where it was met with accidentally by botanists, it is to be
assumed that stray seeds had been casually mixed with those of other
varieties, or that the habit had been transmitted by a spontaneous
cross.
Wherever opportunity led to experiments on heredity, distinct races were
found to be in possession of this quality, while others were not. It is
of no use to cultivate large numbers of wall-flowers in the hope of one
day seeing the anomaly arise; the only means is to secure the strain
from those who have got it. With poppies the various varieties are so
often intercrossed by bees, that the appearance of an accidental change
may sometimes be produced, and in the houseleek the pistilloid warily
seems to be the ordinary one, the normal strain being very rare or
perhaps wholly wanting.
Our three illustrative examples are good and permanent races, producing
their peculiar qualities [372] regularly and abundantly. In this respect
they are however very variable and dependent on external circumstances.
Such a regularity is not met with in other instances. Often
pedigree-experiments lead to poor races, betraying their tendency to
deviate only from time to time and in rare cases.
Pages:
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366