And thus, the strange fact of an increase of fertility in the successive generations of artificially fertilised hybrids, in contrast with those spontaneously self-fertilised, may, as I believe, be accounted for by too close interbreeding having been avoided.

混合性质。 因此，与自发受精的杂交后代相比， 人工受精的杂交后代生育率增加的奇怪事实，我相信，可能是由于避免了过于接近的杂交。