3C IPOMOEA PURPUREA CHAP. II 



at the final measuring. But it is an interesting fact, of which 1 

 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 wag 

 1| 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 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 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 

 25i inches high, and the tallest self-fertilised plants 21|. 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 



