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This eBook from the Gutenberg Project consists of approximately 459 pages of information about Effects of Cross and Self Fertilisation in the Vegetable Kingdom.
of the third generation crossed by a slightly different sub-variety, exceeded greatly in height and weight the self-fertilised plants of the fourth generation; and the trial was made on a large scale.  They exceeded them in height when grown in pots, and not much crowded, in the ratio of 100 to 66; and when much crowded, as 100 to 54.  These crossed plants, when thus subjected to severe competition, also exceeded the self-fertilised in weight in the ratio of 100 to 37.  So it was, but in a less degree (as may be seen in Table 7/C), when the two lots were grown out of doors and not subjected to any mutual competition.  Nevertheless, strange as is the fact, the flowers on the mother-plants of the third self-fertilised generation did not yield more seed when they were crossed with pollen from plants of the fresh stock than when they were self-fertilised.

11.  Anagallis collina.

Plants raised from a red variety crossed by another plant of the same variety were in height to the self-fertilised plants from the red variety as 100 to 73.  When the flowers on the red variety were fertilised with pollen from a closely similar blue-flowered variety, they yielded double the number of seeds to what they did when crossed by pollen from another individual of the same red variety, and the seeds were much finer.  The plants raised from this cross between the two varieties were to the self-fertilised seedlings from the red variety, in height as 100 to 66, and in fertility as 100 to 6.

12.  Primula veris.

Some flowers on long-styled plants of the third illegitimate generation were legitimately crossed with pollen from a fresh stock, and others were fertilised with their own pollen.  From the seeds thus produced crossed plants, and self-fertilised plants of the fourth illegitimate generation, were raised.  The former were to the latter in height as 100 to 46, and in fertility during one year as 100 to 5, and as 100 to 3.5 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.

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