Chap. XVII. SELF-IMPOTENT PLANTS. 117 



The same uatiiralist found in Brazil three plants of a Bignonia 

 growing near together. He fertilised twenty-nine flowerets 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 

 distnict plant, one of the three, and they yielded only two capsules. 

 Lastly, five flowers were fertilised with jDollen from a fourth 

 plant growing at a distance, and all five produced capsules. 

 Fritz Miiller thinks that the three plants which grew near one 

 another were probably seedlings from the same parent, and that 

 from being closely related, they acted very feebly on one another. 

 This view is extremely probable, for he has since shown in a 

 remarkable paper,''^ that in the case of some Brazilian species of 

 Abutilon, which are self-sterile, and between which he raised some 

 comxDlex hybrids, that these, if near relatives, were much less fertile 

 inter se, than when not closely related. 



We now come to cases closely analogous with those just 

 given, but different in so far that only certain individuals 

 of the species are self-sterile. This self-impotence does not 

 depend on the pollen or ovules being in an unfit slate for 

 fertilisation, for both have been found effective in union with 

 other plants of the same or of a distinct species. The fact 

 of plants having acquired so peculiar a constitution, that they 

 can be fertilised more readil}" by the pollen of a distinct 

 species than by their own, is exactly the reverse of what 

 occurs with all ordinary species. For in the latter the two 

 sexual elements of the same individual plant are of course 

 capable of freely acting on each other ; but are so constituted 

 that they are more or less impotent when brought into union 

 with the sexual elements of a distinct species, and produce 

 more or less sterile hybrids. 



Gartner experimented on two plants of Lobeh'a fulgens, brought 

 from separate places, and found ^- that their pollen was good, for he 

 fertihsed with it L. cardinalis and syphilitica ; their ovules were 

 likewise good, for they were fertilised by the pollen of these same 

 two species ; but these two plants oiL.fulgens could not be fertilised 

 by their own pollen, as can generally be effected with perfect ease 

 with this species. Again, the pollen of a plant of Verhascum nigrum 

 grown in a pot was found by Gartner '^ capable of fertilising V. 

 hjchnitis and V. austriacum ; the ovules could be fertilised by the 



" ' Jenaische Zeitschrift fiir Natur- Naturalist,' 1874, p. 223. 

 wiss.* B. vii. p. 22, 1872, and p. 441, "- ' Bastarderzeugung,* s. 64, 357. 



1873. A large part of this paper has ^^ Ibid., s. 357. 



been translated in the ' American 



