64 MIMULUS LUTEUS. CHAP. III. 



the two-lipped stigma, the lips of which are irritable and close 

 like a forceps on the pollen-grains. If no pollen is enclosed 

 between the lips, these open again after a time. Mr. Kitchener 

 has ingeniously explained * the use of these movements, namely, 

 to prevent the self-fertilisation of the flower. If a bee with 

 no pollen on its back enters a flower it touches the stigma, 

 which quickly closes, and when the bee retires dusted with 

 pollen, it can leave none on the stigma of the same flower. 

 But as soon as it enters any other flower, plenty of pollen is 

 left on the stigma, which will be thus cross-fertilised. Never- 

 theless^ if insects are excluded, the flowers fertilise themselves 

 perfectly and produce plenty of seed ; but I did not ascertain 

 whether this is effected by the stamens increasing in length 

 with advancing age, or by the bending down of the pistil. The 

 chief interest in my experiments on the present species, lies in 

 the appearance in the fourth self-fertilised generation of a 

 variety which bore large peculiarly-coloured flowers, and grew 

 to a greater height than the other varieties ; it likewise became 

 more highly self-fertile, so that this variety resembles the 

 plant named Hero, which appeared in the sixth self-fertilised 

 generation of Ipomoea. 



Some flowers on one of the plants raised from the purchased 

 seeds were fertilised with their own pollen ; and others on the 

 same plant were crossed with pollen from a distinct plant. The 

 seeds from twelve capsules thus produced were placed in 

 separate watch-glasses for comparison ; and those from the six 

 crossed capsules appeared to the eye hardly more numerous 

 than those from the six self-fertilised capsules. But when the 

 seeds were weighed, those from the crossed capsules amounted 

 to 1'02 grain, whilst those from the self-fertilised capsules 

 were only '81 grain; so that the former were either heavier or 

 more numerous than the latter, in the ratio of 100 to 79. 



Crossed and self -fertilised Plants of the First Generation. Having 

 ascertained, by leaving crossed and selMertilised seed on damp 

 sand, that they germinated simultaneously, both kinds were 

 thickly sown on opposite sides of a broad and rather shallow 

 pan ; so that the two sets of seedlings, which came up at the 

 same time, were subjected to the same unfavourable conditions. 

 This was a bad method of treatment, but this species was one of 

 the first on which I experimented. When the crossed seedlings 



' A Year's Botany,' 1874, p. 118. 



