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 — C. pedunculatum, C. canaliculatum, or 
C. clefixum—all very distinct from it, produced perfectly 
fertile hybrids ; while other species less different in appearance 
were quite sterile with the same C. 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 sjjecies ; 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 Rhododendron 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 Amaryllidaceoe, by the Hon. and Rev. William Herbert, p. 379. 
