182 NEMOPHILA INSIGNIS. CHAP. V, 



in the same pot were again self-fertilised with pollen from the 

 anthers of other flowers on the same plant. Therefore the degree 

 of self-fertilisation was not quite so close as in the last genera- 

 tion, in which pollen from the same flower, kept in paper, was 

 used. These two lots of seeds were thinly sown on opposite 

 sides of nine pots ; and the young seedlings were thinned, an 

 equal number of nearly as possible the same age being left on 

 the two sides. In the spring of the following year (1870), when 

 the seedlings had grown to a considerable size, they were 

 measured to the tips of their leaves ; and the twenty-three 

 crossed plants averaged 14 04 inches in height, whilst the twenty- 

 three self-fertilised seedlings were 13 '54 inches; or as 100 to 96. 



In the summer of the same year several of these plants 

 flowered, the crossed and self-fertilised plants flowering almost 

 simultaneously, and all the flower-stems were measured. Those 

 produced by eleven of the crossed plants averaged 30 71 inches, 

 and those by nine of the self-fertilised plants 29 '43 inches in 

 height; or as 100 to 96. 



The plants in these nine pots, after they had flowered, were 

 repotted without being disturbed in much larger pots ; and in 

 the following year, 1871, all flowered freely; but they had 

 grown into such an entangled mass, that the separate plants 

 on each side could no longer be distinguished. Accordingly 

 three or four of the tallest flower-stems on each side of each 

 pot were measured; and the measurements in the preceding 

 table are, I think, more trustworthy than the previous ones, 

 from being more numerous, and from the plants being well 

 established and growing vigorously. 



The average height of the thirty-four tallest flower-stems on 

 the twenty-three crossed plants is 29 '82 inches, and that of the 

 same number of flower-stems on the same number of self- 

 fertilised plants is 27-10 inches; or as 100 to 91. So that the 

 crossed plants now showed a decided advantage over their self- 

 fertilised opponents. 



XXII. POLEMONIACE^. NEMOPHILA INSIGNIS. 



Twelve flowers were crossed with pollen from a distinct plant, 

 but produced only six capsules, containing on an average 18 3 

 seeds. Eighteen flowers were fertilised with their own pollen 

 and produced ten capsules, containing on an average 12- 7 



