The others were left to grow to their full height, and were measured when in flower. This accident accounts for the small height of some of the pairs; but as all the pairs, whether only partly or fully grown, were measured at the same time, the measurements are fair.
The average height of the twenty-six crossed plants in the sixteen pots of the two series is 63.29, and that of the twenty-six self-fertilised plants is 41.67 inches; or as 100 to 66. The superiority of the crossed plants was shown in another way, for in every one of the sixteen pots a crossed plant flowered before a self-fertilised one, with the exception of Pot 6 of the second series, in which the plants on the two sides flowered simultaneously.
TABLE 6/88. Nicotiana tabacum. Plants raised from two plants of the third self-fertilised generation in Pots 2 and 5, in Table 6/87.
Heights of plants measured in inches.
Column 1: Number (Name) of Pot.
Column 2: Kew-crossed Plants, pot 2, Table 6/87.
Column 3: Plants of the fourth Self-fertilised generation, pot 2, Table 6/87.
Column 4: Kew-crossed Plants, pot 5, Table 6/87.
Column 5: Plants of the fourth Self-fertilised generation, pot 5, Table 6/87.
Pot 1 : 84 6/8 : 68 4/8 : 77 6/8 : 56. Pot 1 : 31 : 5 : 7 2/8 : 5 3/8.
Pot 2 : 78 4/8 : 51 4/8 : 55 4/8 : 27 6/8. Pot 2 : 48 : 70 : 18 : 7.
Pot 3 : 77 3/8 : 12 6/8 : 76 2/8 : 60 6/8. Pot 3 : 77 1/8 : 6 6/8.
Pot 4 : 49 2/8 : 29 4/8 : 90 4/8 : 11 6/8. Pot 4 : 15 6/8 : 32 : 22 2/8 : 4 1/8.
Pot 5 : 89 : 85 : 94 2/8 : 28 4/8. Pot 5 : 17 : 5 3/8.
Pot 6 : 90 : 80 : 78 : 78 6/8.
Pot 7 : 84 4/8 : 48 6/8 : 85 4/8 : 61 4/8. Pot 7 : 76 4/8 : 56 4/8.
Pot 8 : 83 4/8 : 84 4/8 : 65 5/8 : 78 3/8. Pot 8 : : : 72 2/8 : 27 4/8.
Total : 902.63 : 636.13 : 743.13 : 447.38.
Some of the remaining seeds of both series, whether or not in a state of germination, were thickly sown on the opposite sides of two very large pots; and the six highest plants on each side of each pot were measured after they had grown to nearly their full height. But their heights were much less than in the former trials, owing to their extremely crowded condition. Even whilst quite young, the crossed seedlings manifestly had much broader and finer leaves than the self-fertilised seedlings.
TABLE 6/89. Nicotiana tabacum. Plants of the same parentage as those in Table 6/88, but grown extremely crowded in two large pots.
Heights of plants measured in inches.
Column 1: Kew-crossed Plants, from pot 2, Table 6/87.
Column 2: Plants of the fourth Self-fertilised generation, from pot 2, Table 6/87.
Column 3: Kew-crossed Plants, from pot 5, Table 6/87.
Column 4: Plants of the fourth Self-fertilised generation, from pot 5, Table 6/87.
42 4/8 : 22 4/8 : 44 6/8 : 22 4/8. 34 : 19 2/8 : 42 4/8 : 21. 30 4/8 : 14 2/8 : 27 4/8 : 18. 23 4/8 : 16 : 31 2/8 : 15 2/8. 26 6/8 : 13 4/8 : 32 : 13 5/8. 18 3/8 : 16 : 24 6/8 : 14 6/8.
175.63 : 101.50 : 202.75 : 105.13.
The twelve tallest crossed plants in the two pots belonging to the two series average here 31.53, and the twelve tallest self-fertilised plants 17.21 inches in height; or as 100 to 54. The plants on both sides, when fully grown, some time after they had been measured, were cut down close to the ground and weighed. The twelve crossed plants weighed 21.25 ounces; and the twelve self-fertilised plants only 7.83 ounces; or in weight as 100 to 37.
The rest of the crossed and self-fertilised seeds from the two parent-plants (the same as in the last experiment) was sown on the 1st of July in four long parallel and separate rows in good soil in the open ground; so that the seedlings were not subjected to any mutual competition. The summer was wet and unfavourable for their growth. Whilst the seedlings were very small the two crossed rows had a clear advantage over the two self-fertilised rows.