“Sir John Lubbock says that the evening primrose is probably fertilized by moths, and it would seem at first sight most likely that this should be the case. To-night—for the air, as I have said, is quite still and warm—is just the night that I should expect the moths to be at work; but after long waiting near a large yellow Œnothera (the one plant had forty blooms), I did not see one single moth. I returned to the bed of _Œnothera taraxicifolia_, and again I could see no moth of any kind. Meanwhile, a little further off, among a bed of white Mediterranean heath, which is just as much in flower by day as it is now, there are several of these wanderers of the night—little brown moths of (I think) two different varieties. There and there alone, and not among the large open blossoms of the Œnotheras, or among the delicate tufts of night-scented stock, were the moths busily engaged. Why, then, do these night-flowers—if it be not to attract night insects, and so get fertilized—expand their petals as evening falls? We have, I suspect, a good deal yet to learn on these matters. Even the two Œnotheras are very unlike in several respects. The seed-vessel of the _Œnothera taraxicifolia_ is at the end of a long tube, some seven inches in length, down which runs the stalk or style of the pistil, and within this tube I have constantly found little black flies and grains of pollen. Moreover, the pistil and the stamens of this Œnothera are as nearly as possible the same length; so that even before the flower has opened, a stigma or head of the pistil has got well dusted over with the pollen of the stamens.
“In the case of the large yellow Œnothera the pistil stands out above the stamens, and I suppose it could not be fertilized except by the wind or (more probably) by insects. The tube that leads to the seed-vessel is here only about two inches long, and is not smooth but hairy, so that insects would hardly pass down. Somehow or other, however, the yellow Œnothera bears seed much more certainly and abundantly than the white one. I must add that the veins in both Œnotheras, and especially in the white one, are very strongly marked; so that a theory which carries the high sanction of Sir John Lubbock, that veins are guides to the honey of a flower, and that they do not exist in night-opening flowers, as they would be unseen by night and therefore useless, can hardly, I imagine, be maintained.”