| → seems to me 1859 1860 |
| is 1861 1866 1869 1872 |
|
| → varieties. 1859 1860 1861 |
| varieties, and Naudin has come to the same conclusion. 1866 1869 1872 |
|
|
species were
fertile when intercrossed. But it
→seems to me
impossible to resist the evidence of the existence of a certain amount of sterility in the few following cases, which I will briefly abstract. The evidence is at least as good as that from which we believe in the sterility of a multitude of species. The evidence is, also, derived from hostile witnesses, who in all other cases consider fertility and sterility as safe criterions of specific distinction. Gärtner kept during several years a dwarf kind of maize with yellow seeds, and a tall variety with red
growing near each other in his garden; and although these plants have separated sexes, they never naturally crossed. He then fertilised thirteen flowers of the one
pollen of the other; but only a single head produced any seed, and this one head produced only five grains. Manipulation in this
could not have been injurious, as the plants have separated sexes. No one, I believe, has suspected that these varieties of maize are distinct species; and it is important to notice that the hybrid plants thus raised were themselves
perfectly
fertile; so that even Gärtner did not venture to consider the two varieties as specifically distinct. |
|
| Girou de Buzareingues crossed three varieties of gourd, which like the maize has separated sexes, and he asserts that their mutual fertilisation is by so much the less easy as their differences are greater. How far these experiments may be trusted, I know not; but the forms
are ranked by
who mainly founds his classification by the test of infertility, as
→varieties.
|
|
| The following case is far more remarkable, and seems at first
incredible; but it is the result of an astonishing number of experiments made during many years on nine species of Verbascum, by so good an observer
|
