For our special purpose of comparing the
powers of growth of crossed and self-fertilised plants, it may be said
that in fifty-seven cases the crossed plants exceeded the
self-fertilised by more than five per cent, and that in twenty-six cases
(18 + 8) they did not thus exceed them. But we shall now show that in
several of these twenty-six cases the crossed plants had a decided
advantage over the self-fertilised in other respects, though not in
height; that in other cases the mean heights are not trustworthy, owing
to too few plants having been measured, or to their having grown
unequally from being unhealthy, or to both causes combined.
Nevertheless, as these cases are opposed to my general conclusion I have
felt bound to give them. Lastly, the cause of the crossed plants having
no advantage over the self-fertilised can be explained in some other
cases. Thus a very small residue is left in which the self-fertilised
plants appear, as far as my experiments serve, to be really equal or
superior to the crossed plants.
We will now consider in some little detail the eighteen cases in which
the self-fertilised plants equalled in average height the crossed plants
within five per cent; and the eight cases in which the self-fertilised
plants exceeded in average height the crossed plants by above five per
cent; making altogether twenty-six cases in which the crossed plants
were not taller than the self-fertilised plants in any marked degree.
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