164 DARWINISM chap. 



animals, and presumably from the same cause, too close inter- 

 breeding. 



Dean Herbert, who carried on experiments with great care 

 and skill for many years, found numerous cases of hybrids 

 which were perfectly fertile inter se. Crinum capense, fertilised 

 by three other species — 0. pedunculatum, 0. canaliculatum, or 

 C. defixum — all very distinct from it, produced perfectly 

 fertile hybrids ; while other species less different in appearance 

 were quite sterile with the same 0. capense. 



All the species of the genus Hippeastrum produce hybrid 

 offspring which are invariably fertile. Lobelia syphylitica and 

 L. fulgens, two very distinct species, have produced a hybrid 

 which has been named Lobelia speciosa, and which reproduces 

 itself abundantly. Many of the beautiful pelargoniums of 

 our greenhouses are hybrids, such as P. ignescens from a cross 

 between P. citrinodorum and P. fulgidum, which is quite 

 fertile, and has become the parent of innumerable varieties of 

 beautiful plants. All the varied species of Calceolaria, how- 

 ever different in appearance, intermix with the greatest readi- 

 ness, and the hybrids are all more or less fertile. But the 

 most remarkable case is that of two species of Petunia, of which 

 Dean Herbert says : " It is very remarkable that, although 

 there is a great difference in the form of the flower, especially 

 of the tube, of P. nyctanigenseflora and P. phoenicea the 

 mules between them are not only fertile, but I have found 

 them seed much more freely with me than either parent. 

 .... From a pod of the above-mentioned mule, to which 

 no pollen but its own had access, I had a large batch of seed- 

 lings in which there was no variability or difference from 

 itself ; and it is evident that the mule planted by itself, in a 

 congenial climate, would reproduce itself as a species ; at least 

 as much deserving to be so considered as the various Calceo- 

 larias of different districts of South America." 1 



Darwin was informed by Mr. C. Noble that he raises stocks 

 for grafting from a hybrid between Ehododendron ponticum 

 and R. catawbiense, and that this hybrid seeds as freely as it 

 is possible to imagine. He adds that horticulturists raise 

 large beds of the same hybrid, and such alone are fairly 

 treated ; for, by insect agency, the several individuals are freely 

 1 Amaryllidacece, by the Hon. and Eev. "William Herbert, p. 379. 



