ch 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
is, if the genera of animals are as distinct from each other as are the
genera of plants, then we may infer that animals more widely distinct
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 experiments have been fairly tried: for
instance, the canary-bird has been crossed with nine distinct species of
finches, but, as not one of these breeds freely in confinement, we have
no right to expect that the first crosses between them and the canary,
or that their hybrids, should be perfectly fertile. Again, with respect
to the fertility in successive generations of the more fertile hybrid
animals, I hardly know of an instance in which two families of the same
hybrid have been raised at the same time from different parents, so
as to avoid the ill effects of close interbreeding. On the contrary,
brothers and sisters have usually been crossed in each successive
generation, in opposition to the constantly repeated admonition of every
breeder. And in this case, it is not at all surprising that the inherent
sterility in the hybrids should have gone on increasing.

Although I know of hardly any thoroughly well-authenticated cases of
perfectly fertile hybrid animals, I have reason to believe that the
hybrids from Cervulus vaginalis and Reevesii, and from Phasianus
colchicus with P. torquatus, are perfectly fertile. M. Quatrefages
states that the hybrids from two moths (Bombyx cynthia and arrindia)
were proved in Paris to be fertile inter se for eight generations. It
has lately been asserted that two such distinct species as the hare and
rabbit, when they can be got to breed together, produce offspring, which
are highly fertile when crossed with one of the parent-species. The
hybrids from the common and Chinese geese (A. cygnoides), species which
are so different that they are generally ranked in distinct genera, have
often bred in this country with either pure parent, and in one single
instance they have bred inter se. This was effected by Mr. Eyton, who
raised two hybrids from the same parents, but from differen