The season was unfavourable, and the crossed plants produced only
forty such flower-stems, bearing 168 good capsules, whilst the
self-fertilised plants produced only two such flower-stems, bearing only
6 capsules, half of which were very poor ones. So that the fertility of
the two lots, judging by the number of capsules, was as 100 to 3.5.
In considering the great difference in height and the wonderful
difference in fertility between the two sets of plants, we should bear
in mind that this is the result of two distinct agencies. The
self-fertilised plants were the product of illegitimate fertilisation
during five successive generations, in all of which, excepting the last,
the plants had been fertilised with pollen taken from a distinct
individual belonging to the same form, but which was more or less
closely related. The plants had also been subjected in each generation
to closely similar conditions. This treatment alone, as I know from
other observations, would have greatly reduced the size and fertility of
the offspring. On the other hand, the crossed plants were the offspring
of long-styled plants of the fourth illegitimate generation legitimately
crossed with pollen from a short-styled plant, which, as well as its
progenitors, had been exposed to very different conditions; and this
latter circumstance alone would have given great vigour to the
offspring, as we may infer from the several analogous cases already
given.
Pages:
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336