As the different species
grow to various heights, I have always for the sake of easy comparison
given in addition the average height of the crossed plants of each
species taken as 100, and have calculated the average height of the
self-fertilised plant in relation to this standard. With respect to the
crowded plants raised from the seeds remaining after the pairs had been
planted, and of which only some of the tallest on each side were
measured, I have not thought it worth while to complicate the results by
giving separate averages for them and for the pairs, but have added up
all their heights, and thus obtained a single average.
I long doubted whether it was worth while to give the measurements of
each separate plant, but have decided to do so, in order that it may be
seen that the superiority of the crossed plants over the
self-fertilised, does not commonly depend on the presence of two or
three extra fine plants on the one side, or of a few very poor plants on
the other side. Although several observers have insisted in general
terms on the offspring from intercrossed varieties being superior to
either parent-form, no precise measurements have been given (1/8. A
summary of these statements, with references, may be found in my
'Variation of Animals and Plants under Domestication' chapter 17 2nd
edition 1875 volume 2 page 109.); and I have met with no observations on
the effects of crossing and self-fertilising the individuals of the same
variety.
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