"Perhaps there had been, once, when the air was thick enough to support insects, but now most of the Martian plant-life was self-fertilised."
"Now Henslow, in his “Floral Structures,” [18] adopts the same theory for all the wind-fertilised or self-fertilised flowers, and he tells me that he is alone in the view."
"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."