The flowers on the plants from the
cross with the purple-flowered Westerham stock were, as might have been
expected, much more purple and not nearly so uniform in tint. The
self-fertilised plants were also remarkably uniform in height, as judged
by the eye; the intercrossed less so, whilst the Westerham-crossed
plants varied much in height.
Nicotiana tabacum.
This plant offers a curious case. Out of six trials with crossed and
self-fertilised plants, belonging to three successive generations, in
one alone did the crossed show any marked superiority in height over the
self-fertilised; in four of the trials they were approximately equal;
and in one (i.e., in the first generation) the self-fertilised plants
were greatly superior to the crossed. In no case did the capsules from
flowers fertilised with pollen from a distinct plant yield many more,
and sometimes they yielded much fewer seeds than the capsules from
self-fertilised flowers. But when the flowers of one variety were
crossed with pollen from a slightly different variety, which had grown
under somewhat different conditions,--that is, by a fresh stock,--the
seedlings derived from this cross exceeded in height and weight those
from the self-fertilised flowers in an extraordinary degree.
Twelve flowers on some plants of the common tobacco, raised from
purchased seeds, were crossed with pollen from a distinct plant of the
same lot, and these produced ten capsules.
Pages:
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309