306 UNIFORM COLOUR OF THE FLOWERS CHAP. VIII. 



valuable experiments on hybrid Abutilons, that the 

 union of brothers and sisters, parents and children, 

 and of other near relations is highly injurious to the 

 fertility of the offspring. In one case, moreover, seed- 

 lings from such near relations possessed very weak 

 constitutions.* This same observer also found f three 

 plants of a Bignonia growing near together. He fer- 

 tilised twenty-nine flowers on one of them with their 

 own pollen, and they did not set a single capsule. 

 Thirty flowers were then fertilised with pollen from 

 a distinct plant, one of the three growing together, 

 and they yielded only two capsules. Lastly, five 

 flowers were fertilised with pollen from a fourth plant 

 growing at a distance, and all five produced capsules. 

 It seems therefore probable, as Fritz Miiller suggests, 

 that the three plants growing near together were 

 seedlings from the same parent, and that from being 

 closely related they had little power of fertilising one 

 another.^ 



Lastly, the fact of the intercrossed plants in 

 Table A not exceeding in height the self-fertilised 

 plants in a greater and greater degree in the later 

 generations, is probably due to their having become 

 more and more closely inter-related. 



Uniform Colour of the Flowers on Plants, self -fertilised 

 and grown under similar conditions for several Genera- 

 tions. At the commencement of my experiments, the 

 parent-plants of Mimulus luteus, Ipomoea purpurea, 

 Dianthus caryophyllus, and Petunia violacea, raised 

 from purchased seeds, varied greatly in the colour 



* 'Jenaische Zeitschrift fur Domestication' ("chap, xvii. 2nd 



Naturw.; B. vii., pp. 22 and 45, edit. vol. 2, p. 121) of hybrids of 



1872 ; and 1873, pp. 441-450. Gladiolus and Cistus, any one of 



t ' Bot. Zeitunt?,' 1868, p. 626. which could be fertilised by pollen 



j Some remarkable caaea are from any other, but nc t by its 



given in my ' Variation under own pollen. 



