Effects of Cross and Self Fertilisation in the Vegetable Kingdom eBook

This eBook from the Gutenberg Project consists of approximately 516 pages of information about Effects of Cross and Self Fertilisation in the Vegetable Kingdom.

Effects of Cross and Self Fertilisation in the Vegetable Kingdom eBook

This eBook from the Gutenberg Project consists of approximately 516 pages of information about Effects of Cross and Self Fertilisation in the Vegetable Kingdom.
were to the intercrossed in height as 126 to 100.  In the sixth generation they were likewise much taller and finer plants, but were not actually measured; they produced capsules compared with those on the intercrossed plants, in number, as 147 to 100; and the self-fertilised capsules contained a greater number of seeds.  In the seventh generation the self-fertilised plants were to the crossed in height as 137 to 100; and twenty flowers on these self-fertilised plants fertilised with their own pollen yielded nineteen very fine capsules,—­a degree of self-sterility which I have not seen equalled in any other case.  This variety seems to have become specially adapted to profit in every way by self-fertilisation, although this process was so injurious to the parent-plants during the first four generations.  It should however be remembered that seedlings raised from this variety, when crossed by a fresh stock, were wonderfully superior in height and fertility to the self-fertilised plants of the corresponding generation.

Secondly, in the sixth self-fertilised generation of Ipomoea a single plant named the Hero appeared, which exceeded by a little in height its intercrossed opponent,—­a case which had not occurred in any previous generation.  Hero transmitted the peculiar colour of its flowers, as well as its increased tallness and a high degree of self-fertility, to its children, grandchildren, and great-grandchildren.  The self-fertilised children of Hero were in height to other self-fertilised plants of the same stock as 100 to 85.  Ten self-fertilised capsules produced by the grandchildren contained on an average 5.2 seeds; and this is a higher average than was yielded in any other generation by the capsules of self-fertilised flowers.  The great-grandchildren of Hero derived from a cross with a fresh stock were so unhealthy, from having been grown at an unfavourable season, that their average height in comparison with that of the self-fertilised plants cannot be judged of with any safety; but it did not appear that they had profited even by a cross of this kind.

Thirdly, the plants of Nicotiana on which I experimented appear to come under the present class of cases; for they varied in their sexual constitution and were more or less highly self-fertile.  They were probably the offspring of plants which had been spontaneously self-fertilised under glass for several generations in this country.  The flowers on the parent-plants which were first fertilised by me with their own pollen yielded half again as many seeds as did those which were crossed; and the seedlings raised from these self-fertilised seeds exceeded in height those raised from the crossed seeds to an extraordinary degree.  In the second and third generations, although the self-fertilised plants did not exceed the crossed in height, yet their self-fertilised flowers yielded on two occasions considerably more seeds than the crossed flowers, even than those which were crossed with pollen from a distinct stock or variety.

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Effects of Cross and Self Fertilisation in the Vegetable Kingdom from Project Gutenberg. Public domain.