this peculiar condition. So that with some species,
certain abnormal individuals, and in other species all the individuals,
can actually be hybridised much more readily than they can be fertilised
by pollen from the same individual plant! To give one instance, a bulb
of Hippeastrum aulicum produced four flowers; three were fertilised
by Herbert with their own pollen, and the fourth was subsequently
fertilised by the pollen of a compound hybrid descended from three
distinct species: the result was that "the ovaries of the three first
flowers soon ceased to grow, and after a few days perished entirely,
whereas the pod impregnated by the pollen of the hybrid made vigorous
growth and rapid progress to maturity, and bore good seed, which
vegetated freely." Mr. Herbert tried similar experiments during many
years, and always with the same result. These cases serve to show on
what slight and mysterious causes the lesser or greater fertility of a
species sometimes depends.

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, etc., 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, "reproduces itself as perfectly as if it had been a
natural species from the mountains of Chile." 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. ponticum and catawbiense, and that
this hybrid "seeds as freely as it is possible to imagine." Had hybrids,
when fairly treated, always gone on decreasing in fertility in each
successive generation, as Gartner believed to be the case, the fact
would have been notorious to nurserymen. Horticulturists raise large
beds of the same hybrid, and such alone are fairly treated, for by
insect agency the several individuals are allowed to cross freely 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 Rhododendrons, whi