| The practical experiments of horticulturists, though not made with scientific precision, deserve some notice. It is notorious in how complicated a manner the species of Pelargonium, Fuchsia, Calceolaria, Petunia, Rhododendron, &c., have been crossed, yet many of these hybrids seed freely. For instance, Herbert asserts that a hybrid from Calceolaria integrifolia and plantaginea, species most widely dissimilar in general habit,
itself as perfectly as if it had been a natural species from the mountains of
I have taken some pains to ascertain the degree of fertility of some of the complex crosses of Rhododendrons, and I am assured that many of them are perfectly fertile. Mr. C. Noble, for instance, informs me that he raises stocks for grafting from a hybrid between Rhod.
and
and that this hybrid "seeds as freely as it is possible to imagine." Had hybrids, when fairly treated,
on decreasing in fertility in each successive generation, as Gärtner
to be the case, the fact would have been notorious to
Horticulturists raise large beds of the same
and such alone are fairly treated, for by insect agency the several individuals
→OMIT
are allowed to
with each other, and the injurious influence of close interbreeding is thus prevented. Any one may readily convince himself of the efficiency of insect-agency by examining the flowers of the more sterile kinds of hybrid
which produce no pollen, for he will find on their stigmas plenty of pollen brought from other flowers. |
| In regard to animals, much fewer experiments have been carefully tried than with plants. If our systematic arrangements can be trusted, that
if the genera of animals are as distinct from each
as are the genera of plants, then we may infer that animals more widely
in the scale of nature can be
→crossed more easily
than in the case of plants; but the hybrids themselves are, I think, more sterile.
It should, however, be borne in mind that, owing to few animals breeding freely under confinement, few
|
