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Show 42 IPOMCEA PURPUREA. CHAP. II. over the offspring from flowe.rs fertilised with their own pollen. I procured some fresh seed and raised two plants, which were covered with a net; and several of their flowers were crossed with pollen from a listinct flower on the same plant. Twenty-nine capsules thus produced contained on an average 4 · 8G seeds per capsule; and 100 of these seeds weighed 36 · 77 grains. Several other flowers were fertilised with their own pollen, and twenty-six capsules thus produced contained on an average 4 · 42 seeds per capsule ; 100 of which weighed 42 · 61 grains. So that a cross of this kind appears to have increased slightly the number of seeds per capsule, in the ratio of 100 to 91 ; but these crossed seeds were lighter than the self-fertilised in the ratio of 86 to 100. I doubt, however, from other observations, whether these results are fully trustworthy. The two lots of seeds, after germinating on sand, were planted in pairs on the opposite sides of nine pots, and were treated in every respect like the plants in the previous experiments. The remaining seeds, some in a state of germination and some not so, were sown on the opposite sides of a large pot (No. X.); and the four tallest plants on each side of this pot were measured. The result is shown in the following table:- The average height of the thirty-one crossed plants is 73 · 23 inches, and that of the thirty-one self-fertilised plants 77 · 41 inches; or as 100 to 106. Looking to each pair, it may be seen that only thirteen of the crossed plants, whilst eighteen of the - self-fertilised plants exceed their opponents. A record was kept with respect to the plant which flowered first in each pot; and only two of the crossed flowered before one of the self-fertilised in the same pot; whilst eight of the self· fertilised flowered first. It thus appears that the CHAP. II. FLOWERS ON SAME PLANT CROSSED. 43 TABLE XII. No. of Pot, I Cros~ed Plants. I Self-fertilised Plants. - . I. Inc-hes. Inches. 82 77~ 75 87 65 64 76 87§ II. 78~ 84 40 86~ 6~t:>4g 903 - III. 61i 86 85 69~ 89 87 ~ - IV. 83 803 73~ 88~ 67 84~ v. 78 66~ 76g 77 ~ 57 8q VI. 70~ 80 79 82~ 79~ 55~ VII. ' 76 77 84~ 83~ 79 73~ VIII. 73 76~ 67 82 83 RO~ IX. 73~ 78~ 78 67 ~ X. 34 82~ Crowded plants. 82 3"'6 84~ Og 69~ 71 75~ 1- Total inches. I 2270•25 - 2399•75 ,_ - |