| → distinct species of 1872 |
| other 1859 1860 1861 1866 1869 |
|
| ↑ 1 blocks not present in 1872; present in 1859 1860 1861 1866 1869 |
| If we were to act thus, and pair brothers and sisters in the case of any pure animal, which from any cause had the least tendency to sterility, the breed would assuredly be lost in a very
few generations.
|
|
| → OMIT 1866 1869 1872 |
| and with P. versicolor 1859 1860 |
| and with P. versicolor, 1861 |
|
| → offspring, which are highly fertile when crossed with one of the parent-species. 1872 |
| almost perfectly fertile offspring; but this statement is as yet very doubtful. 1869 |
|
| → or perfectly fertile. 1866 1869 1872 |
| fertile. 1859 1860 1861 |
|
| → With our domesticated animals, the 1872 |
| The 1869 |
|
| → when crossed together 1872 |
| of each kind of domesticated animal 1869 |
|
| → OMIT 1872 |
| when crossed together; 1869 |
|
| → at first produced 1872 |
| produced at first 1869 |
|
| → which was first propounded by Pallas, seems by far 1872 |
| seems to me 1859 1860 |
| seems 1861 1866 |
| which was first propounded by Pallas, seems 1869 |
|
|
experiments have been fairly tried: for instance, the canary-bird has been crossed with nine
→distinct species of
finches,
as not one of these
breeds freely in confinement, we have no right to expect that the first crosses
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
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.
→OMIT
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.
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 This was effected by Mr. Eyton, who raised two hybrids from the same
but from different hatches; and from these two birds he raised no less than
hybrids (grandchildren of the pure geese) from one nest. In India, however, these cross-bred geese must be far more fertile; for I am assured by two eminently capable judges, namely Mr. Blyth and Capt. Hutton, that whole flocks of these crossed geese are kept in various parts of the country; and as they are kept for profit, where neither pure parent-species exists, they must certainly be highly
→or perfectly fertile.
|
|
|
→With our domesticated animals, the
various races
→when crossed together
are quite
→OMIT
yet in many cases they are descended from two or more wild species. From this fact we must conclude either that the aboriginal parent-species
→at first produced
perfectly fertile hybrids, or that the hybrids subsequently reared under domestication became quite fertile. This latter
→which was first propounded by Pallas, seems by far
|
