Chapter 2 - Page 2

Pot 2 : 87 : 60 4/8.

Pot 3 : 77 : 57. Plants crowded; the tallest one measured on each side.

Total : 516 : 394.

The average height of the six crossed plants is here 86 inches, whilst that of the six self-fertilised plants is only 65.66 inches, so that the crossed plants are to the self-fertilised in height as 100 to 76. It should be observed that this difference is not due to a few of the crossed plants being extremely tall, or to a few of the self-fertilised being extremely short, but to all the crossed plants attaining a greater height than their antagonists. The three pairs in Pot 1 were measured at two earlier periods, and the difference was sometimes greater and sometimes less than that at the final measuring. But it is an interesting fact, of which I have seen several other instances, that one of the self-fertilised plants, when nearly a foot in height, was half an inch taller than the crossed plant; and again, when two feet high, it was 1 3/8 of an inch taller, but during the ten subsequent days the crossed plant began to gain on its antagonist, and ever afterward asserted its supremacy, until it exceeded its self-fertilised opponent by 16 inches.

The five crossed plants in Pots 1 and 2 were covered with a net, and produced 121 capsules; the five self-fertilised plants produced eighty-four capsules, so that the numbers of capsules were as 100 to 69. Of the 121 capsules on the crossed plants sixty-five were the product of flowers crossed with pollen from a distinct plant, and these contained on an average 5.23 seeds per capsule; the remaining fifty-six capsules were spontaneously self-fertilised. Of the eighty-four capsules on the self-fertilised plants, all the product of renewed self-fertilisation, fifty-five (which were alone examined) contained on an average 4.85 seeds per capsule. Therefore the cross-fertilised capsules, compared with the self-fertilised capsules, yielded seeds in the proportion of 100 to 93. The crossed seeds were relatively heavier than the self-fertilised seeds. Combining the above data (i.e., number of capsules and average number of contained seeds), the crossed plants, compared with the self-fertilised, yielded seeds in the ratio of 100 to 64.

These crossed plants produced, as already stated, fifty-six spontaneously self-fertilised capsules, and the self-fertilised plants produced twenty-nine such capsules. The former contained on an average, in comparison with the latter, seeds in the proportion of 100 to 99.

In Pot 3, on the opposite sides of which a large number of crossed and self-fertilised seeds had been sown and the seedlings allowed to struggle together, the crossed plants had at first no great advantage. At one time the tallest crossed was 25 1/8 inches high, and the tallest self-fertilised plants 21 3/8. But the difference afterwards became much greater. The plants on both sides, from being so crowded, were poor specimens. The flowers were