Hereafter I shall have to recur to this subject of the inefficiency of a
cross between the flowers on the same plant, when we consider the part
which insects play in the cross-fertilisation of flowers.
ON THE TRANSMISSION OF THE GOOD EFFECTS FROM A CROSS AND OF THE EVIL
EFFECTS FROM SELF-FERTILISATION.
We have seen that seedlings from a cross between distinct plants almost
always exceed their self-fertilised opponents in height, weight, and
constitutional vigour, and, as will hereafter be shown, often in
fertility. To ascertain whether this superiority would be transmitted
beyond the first generation, seedlings were raised on three occasions
from crossed and self-fertilised plants, both sets being fertilised in
the same manner, and therefore not as in the many cases given in Tables
7/A, 7/B, 7/C, in which the crossed plants were again crossed and the
self-fertilised again self-fertilised.
Firstly, seedlings were raised from self-fertilised seeds produced under
a net by crossed and self-fertilised plants of Nemophila insignis; and
the latter were to the former in height as 133 to 100. But these
seedlings became very unhealthy early in life, and grew so unequally
that some of them in both lots were five times as tall as the others.
Therefore this experiment was quite worthless; but I have felt bound to
give it, as opposed to my general conclusion. I should state that in
this and the two following trials, both sets of plants were grown on the
opposite sides of the same pots, and treated in all respects alike.
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