My dear Bentham

Very many thanks for the specimen, which sufficed for one purpose & would hardly do, if I had a whole spike, for my other purpose.— I will write to Tenby.² I daresay the “Supplements” may be unavoidable, but I cannot help thinking they will be a fertile source of wrong references, from which I often suffer in an outrageous manner.³

By the way I may mention one great difficulty which I have on my subject of Orchids; viz that several species, which are habitually visited by insects (moths almost certainly) never secrete within their nectaries or on the Labellum an atom of honey. I have now daily watched O. morio for 23 days and tried all sorts of devices. C. C. Sprengel and Kurr make similar statements about this and other species.⁴ Orchis Conopsea & some other species secrete abundantly; and this makes me so much wish to see spec. of O. pyramidalis without nectarys. C. C. Sprengel & Kurr believe that these orchids exist by an organised system of deception & that moths go on visiting them in hopes of finding nectar;⁵ I cannot swallow the belief of such roguery.⁶ Do you know whether nectar is ever secreted & reabsorbed promptly?— I am utterly puzzled: I have watched the nectaries till 11$\frac{1}{2}$ at night & all as dry as a bone.—

Here is a piece of presumption! I must think that you are mistaken in ranking Hab. chlorantha as a var. of H. bifolia:⁷ the pollen-masses & stigma differ more than in most of the best species of Orchis. When I first examined them, I remember telling Hooker that moths would, I felt sure, fertilise them in a different manner; & I have just had proof of this in moth sent me with the pollinia (which can be easily recognised) of H. chlorantha attached to its proboscis, instead of to the sides of its face, as in Hab. bifolia.—⁸

Forgive me scribbling this way; but when a man gets on his hobby-horse, he always is run away with.— Anyhow nothing here requires any answer; unless, indeed, you chance to have any light about the nectar.

Yours very sincerely | Chas. Darwin

P.S. | I have just received owing to your or Hooker’s kindness a copy of your Elementary Principles of Botany, which pleases him much & for which I thank either you or Hooker.—⁹