5
during the next year. In this case, however, we have no means of
distinguishing between the evil effects of illegitimate fertilisation
continued during four generations (that is, by pollen of the same form,
but taken from a distinct plant) and strict self-fertilisation. But it
is probable that these two processes do not differ so essentially as at
first appears to be the case. In the following experiment any doubt
arising from illegitimate fertilisation was completely eliminated.
13. Primula veris. (Equal-styled, red-flowered variety.)
Flowers on plants of the second self-fertilised generation were crossed
with pollen from a distinct variety or fresh stock, and others were
again self-fertilised. Crossed plants and plants of the third
self-fertilised generation, all of legitimate origin, were thus raised;
and the former was to the latter in height as 100 to 85, and in
fertility (as judged by the number of capsules produced, together with
the average number of seeds) as 100 to 11.
SUMMARY OF THE MEASUREMENTS IN TABLE 7/C.
This table includes the heights and often the weights of 292 plants
derived from a cross with a fresh stock, and of 305 plants, either of
self-fertilised origin, or derived from an intercross between plants of
the same stock. These 597 plants belong to thirteen species and twelve
genera. The various precautions which were taken to ensure a fair
comparison have already been stated.
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