30 IPOMCEA PURPUREA., Chap. II, 



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 

 If 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 I. and II. 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, com- 

 pared with the self-fertilised capsules, yielded seeds in tho 

 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 con- 

 tained on an average, in comparison with the latter, seeds 

 in the proportion of 100 to 99. 



In Pot III., on the opposite sides of which a large number of 

 crossed and self-fertilised seeds had been sown and the seed- 

 lings allowed to struggle together, the crossed plants had at 

 first no great advantage. At one time the tallest crossed was 

 25^ inches high, and the tallest self-fertilised plants 21f . But 

 the difference afterwards became much greater. The plants on 

 both sides, from being so crowded, were poor specimens. The 

 flowers were allowed to fertilise themselves spontaneously under 

 a net; the crossed. plants produced thirty-seven capsules, the 

 self-fertilised plants only eighteen, or as 100 to 47. The former 

 contained on an average 3 62 seeds per capsule ; and the latter 

 3 - 38 seeds, or as 100 to 93. Combining these data (i.e., number 



