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Fertilisation of British Orchids by Insect Agency.—I am much obliged to Mr. Marshall,¹ of Ely, for his statement that the 15 plants of Fly Orchis (Ophrys muscifera) which does not grow in his neighbourhood, but which flourished in his garden, had not one of their pollen masses removed. The Orchis maculata, on the other hand, which likewise does not grow in the neighbourhood, had all its pollen masses removed. Mr. Marshall is not perhaps aware that different insects haunt different Orchids, and are necessary for their fertilisation.² From the wide difference in shape of the flower of Orchis and Ophrys, I should have anticipated that they would be visited and fertilised by different insects. In Listera, for instance, it is chiefly Ichneumonidæ, and sometimes flies, which by day perform the marriage ceremony. In the case of most Orchids it is nocturnal moths. Orchis pyramidalis, however, is visited by Zygæna, and I have examined one of these day-sphinxes with three pair of pollen-masses firmly attached to its proboscis. There can hardly be a doubt that the Butterfly Orchis is visited by different moths from most of the smaller Orchids; and I have recognised its peculiar pollen-masses attached to the sides of the face of certain moths. It is probable that the same kind of moths would visit all the species of true Orchis, which closely resemble each other in structure. Thus the Orchis conopsea, planted in a garden some miles from where any native plant grew, had its pollen-masses removed; so this is a parallel case with that of O. maculata given by Mr. Marshall. I have also transplanted the rare Malaxis to a place about two miles from its native bog, and it was immediately visited by some insect, and its pollen-masses were removed. On the other hand, the Epipactis latifolia, growing in my garden and flowering well, had not its pollen-masses removed; though in its own home, several miles distant, the flowers are regularly visited and thus fertilised. We thus see that the seeds of an Orchid might be carried by the wind to some distant place, and there germinate, but that the species would not be perpetuated unless the proper insects inhabited the site. I have now Goodyera repens growing in my garden, and I shall be curious to see next summer whether our southern insects discover or appreciate the nectar of this Highland Orchid.³ C. Darwin.

¹ William Marshall (1815-1890), botanist and solicitor. Darwin refers to Marshall 1861 which was a response to Darwin 1860. See Correspondence vol. 9.

² See Orchids, pp. 36-8.

³ See Orchids, pp. 112-16.