From Friedrich Hildebrand 16 July 1863
July 16th | 1863.
induced by your work on the fertilisation of Orchids1 I have made some interesting observations, not so much respecting the fertilisation by insects as the effects of the pollen applied to the stigma. Therefore I venture to send you an extract of a little treatise that is going to be printed in 〈the〉 Botanische Zeitung, and I shoul〈d be〉 very much obliged to you if 〈you〉 would read it in one of 〈your〉 botanical societies, or g〈et it〉 printed anywhere.—2
This last summer Professor Treviranus and myself have made observations on almost all the Orchids of our flora and can verify almost all you have said about them.3 We observed also the selffertilisation of Ophrys apifera, I suppose Professor Treviranus will tell you more about it, as he would not believe at first in this selffertilisation.4
I am very much inclined to believe with you that there are certain Orchids as Acropera and Catasetum with their sexes separated, but after having read my observations you will agree with me that the absence or the incomplete state of the ovules 〈can〉not be called a proof for the 〈ma〉le sex of the plant.5 I am sure 〈you〉 will find the ovules very 〈incomp〉letely developped in almost 〈any tropi〉cal Orchid you will look at.6
Your very interesting experiments on Linum perenne I have made with the same result.7 I had a plant of the short-styled form in my room, a part of the flowers were fertilised with each other, another part each flower with itself, and of both kinds of fertilisation I got no capsule; a third part of flowers on the same plant I fertilised with pollen of the long styled form and got a good capsule of almost every flower.— With my experiments on Primula I have not come to an end as yet.8
I hope you will excuse my letter the more as I remember the kind answer I got on my former letter to you about the German translation of your Fertilisation of Orchids,9 and remain dear Sir | yours | respectfully | F Hildebrand
He and L. C. Treviranus have repeated many of CD’s orchid observations with the same results. Sends his paper ["Fruchtbildung der Orchideen", Bot. Ztg. 21 (1863): 329–33, 337–45].