Young crossed seedlings of Nicotiana withstood a
cold and wet summer much better than the self-fertilised seedlings. I
have met with only one exception to the rule of crossed plants being
hardier than the self-fertilised: three long rows of Eschscholtzia
plants, consisting of crossed seedlings from a fresh stock, of
intercrossed seedlings of the same stock, and of self-fertilised ones,
were left unprotected during a severe winter, and all perished except
two of the self-fertilised. But this case is not so anomalous as it at
first appears, for it should be remembered that the self-fertilised
plants of Eschscholtzia always grow taller and are heavier than the
crossed; the whole benefit of a cross with this species being confined
to increased fertility.
Independently of any external cause which could be detected, the
self-fertilised plants were more liable to premature death than were the
crossed; and this seems to me a curious fact. Whilst the seedlings were
very young, if one died its antagonist was pulled up and thrown away,
and I believe that many more of the self-fertilised died at this early
age than of the crossed; but I neglected to keep any record. With Beta
vulgaris, however, it is certain that a large number of the
self-fertilised seeds perished after germinating beneath the ground,
whereas the crossed seeds sown at the same time did not thus suffer.
When a plant died at a somewhat more advanced age the fact was recorded;
and I find in my notes that out of several hundred plants, only seven of
the crossed died, whilst of the self-fertilised at least twenty-nine
were thus lost, that is more than four times as many.
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