CHAP. VI. COLOUR OF THE FLOWERS. 203 



flowers on all these plants having been left to be freely crossed 

 by insects or to fertilise themselves. The Westerham-crossed 

 plants were also much taller and heavier plants than the self- 

 fertilised, both in the pots and open ground ; but they were less 

 tall and heavy than the intercrossed plants. This latter result, 

 however, would almost certainly have been reversed, if the 

 plants had been allowed to grow for another month, as the 

 Westerham-crossed were still growing vigorously, whilst the 

 intercrossed had almost ceased to grow. This case reminds us of 

 the somewhat analogous one of Eschscholtzia, in which plants 

 raised from a cross with a fresh stock did not grow higher than 

 the self-fertilised or intercrossed plants, but produced a greater 

 number of seed-capsules, which contained a far larger average 

 number of seeds. 



Colour of the Flowers on the above Three Lots of Plants. The 

 original mother-plant, from which the five successive self-fertilised 

 generations were raised, bore dingy purple flowers. At no time 

 was any selection practised, and the plants were subjected in 

 each generation to extremely uniform conditions. The result 

 was, as in some previous cases, that the flowers on all the self- 

 fertilised plants, both in the pots and open ground, were 

 absolutely uniform in tint; this being a dull, rather peculiar 

 flesh colour. This uniformity was very striking in the long row 

 of plants growing in the open ground, and these first attracted 

 my attention. I did not notice in which generation the original 

 colour began to charge and to become uniform, but I have every 

 reason to believe that the change was gradual. The flowers on 

 the intercrossed plants were mostly of the same tint, but not 

 nearly so uniform as those on the self-fertilised plants, and many of 

 them were pale, approaching almost to white. The flowers on the 

 plants from the cross with the purple-flowered Westerham stock 

 were, as might have been expected, much more purple and not 

 nearly so uniform in tint. The self-fertilised plants were also 

 remarkably uniform in height, as judged by the eye; the inter- 

 crossed less so, whilst the Westerham-crossed plants varied much 

 in height. 



NlCOTIANA TABAOUM. 



This plant offers a curious case. Out of six trials with crossed 

 and self-fertilised plants, belonging to three successive genera- 

 tions, in one alone did the crossed show any marked superiority 

 in height over the self-fertilised ; in four of the trials they were 



