4. Iberis umbellata.
Seedlings from a crimson English variety crossed by a pale-coloured
variety which had been grown for some generations in Algiers, were to
the self-fertilised seedlings from the crimson variety in height as 100
to 89, and as 100 to 75 in fertility. I am surprised that this cross
with another variety did not produce a still more strongly marked
beneficial effect; for some intercrossed plants of the crimson English
variety, put into competition with plants of the same variety
self-fertilised during three generations, were in height as 100 to 86,
and in fertility as 100 to 75. The slightly greater difference in height
in this latter case, may possibly be attributed to the deteriorating
effects of self-fertilisation carried on for two additional generations.
5. Eschscholtzia californica.
This plant offers an almost unique case, inasmuch as the good effects of
a cross are confined to the reproductive system. Intercrossed and
self-fertilised plants of the English stock did not differ in height
(nor in weight, as far as was ascertained) in any constant manner; the
self-fertilised plants usually having the advantage. So it was with the
offspring of plants of the Brazilian stock, tried in the same manner.
The parent-plants, however, of the English stock produced many more
seeds when fertilised with pollen from another plant than when
self-fertilised; and in Brazil the parent-plants were absolutely sterile
unless they were fertilised with pollen from another plant.
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