The reader should remember that these capsules are the product of cross-fertilisation, effected by the bees; and that the difference in the number of the contained seeds must depend on the constitution of the plants;—that is, on whether they were derived from a cross with a distinct stock, or from a cross between plants of the same stock, or from self-fertilisation. From the above facts we obtain the following ratios:—
Number of seeds contained in an equal number of naturally fertilised capsules produced:—
By the English-crossed and self-fertilised plants, as 100 to 63.
By the English-crossed and intercrossed plants, as 100 to 81.
By the intercrossed and self-fertilised plants, as 100 to 78.
But to have ascertained the productiveness of the three lots of plants, it would have been necessary to know how many capsules were produced by the same number of plants. The three long rows, however, were not of quite equal lengths, and the plants were much crowded, so that it would have been extremely difficult to have ascertained how many capsules were produced by them, even if I had been willing to undertake so laborious a task as to collect and count all the capsules. But this was feasible with the plants grown in pots in the greenhouse; and although these were much less fertile than those growing out of doors, their relative fertility appeared, after carefully observing them, to be the same. The nineteen plants of the English-crossed stock in the pots produced altogether 240 capsules; the intercrossed plants (calculated as nineteen) produced 137.22 capsules; and the nineteen self-fertilised plants, 152 capsules. Now, knowing the number of seeds contained in forty-five capsules of each lot, it is easy to calculate the relative numbers of seeds produced by an equal number of the plants of the three lots.
Number of seeds produced by an equal number of naturally-fertilised plants:—
Plants of English-crossed and self-fertilised parentage, as 100 to 40 seeds.
Plants of English-crossed and intercrossed parentage, as 100 to 45 seeds.
Plants of intercrossed and self-fertilised parentage, as 100 to 89 seeds.