Gray, June 8, 1860:--
"Talking of adaptation, I have lately been looking at our common orchids, and I dare say the facts are as old and well-known as the hills, but I have been so struck with admiration at the contrivances, that I have sent a notice to the "Gardeners' Chronicle". The Ophrys apifera, offers, as you will see, a curious contradiction in structure."
Besides attending to the fertilisation of the flowers he was already, in 1860, busy with the homologies of the parts, a subject of which he made good use in the Orchid book. He wrote to Sir Joseph Hooker (July):--
"It is a real good joke my discussing homologies of Orchids with you, after examining only three or four genera; and this very fact makes me feel positive I am right! I do not quite understand some of your terms; but sometime I must get you to explain the homologies; for I am intensely interested on the subject, just as at a game of chess."
This work was valuable from a systematic point of view. In 1880 he wrote to Mr. Bentham:--
"It was very kind in you to write to me about the Orchideae, for it has pleased me to an extreme degree that I could have been of the LEAST use to you about the nature of the parts."
The pleasure which his early observations on Orchids gave him is shown in such extracts as the following from a letter to Sir J.D. Hooker (July 27, 1861):--
"You cannot conceive how the Orchids have delighted me. They came safe, but box rather smashed; cylindrical old cocoa- or snuff-canister much safer. I enclose postage. As an account of the movement, I shall allude to what I suppose is Oncidium, to make CERTAIN,--is the enclosed flower with crumpled petals this genus? Also I most specially want to know what the enclosed little globular brown Orchid is. I have only seen pollen of a Cattleya on a bee, but surely have you not unintentionally sent me what I wanted most (after Catasetum or Mormodes), viz. one of the Epidendreae?! I PARTICULARLY want (and will presently tell you why) another spike of this little Orchid, with older flowers, some even almost withered."
His delight in observation is again shown in a letter to Dr. Gray (1863). referring to Cruger's letters from Trinidad, he wrote:--"Happy man, he has actually seen crowds of bees flying round Catasetum, with the pollinia sticking to their backs!"
The following extracts of letters to Sir J.D. Hooker illustrate further the interest which his work excited in him:--
"Veitch sent me a grand lot this morning. What wonderful structures!
"I have now seen enough, and you must not send me more, for though I enjoy looking at them MUCH, and it has been very useful to me, seeing so many different forms, it is idleness. For my object each species requires studying for days. I wish you had time to take up the group. I would give a good deal to know what the rostellum is, of which I have traced so many curious modifications. I suppose it cannot be one of the stigmas (It is a modification of the upper stigma.), there seems a great tendency for two lateral stigmas to appear. My paper, though touching on only subordinate points will run, I fear, to 100 MS. folio pages! The beauty of the adaptation of parts seems to me unparalleled. I should think or guess waxy pollen was most differentiated. In Cypripedium which seems least modified, and a much exterminated group, the grains are single. In ALL OTHERS, as far as I have seen, they are in packets of four; and these packets cohere into many wedge-formed masses in Orchis; into eight, four, and finally two. It seems curious that a flower should exist, which could AT MOST fertilise only two other flowers, seeing how abundant pollen generally is; this fact I look at as explaining the perfection of the contrivance by which the pollen, so important from its fewness, is carried from flower to flower" (1861).
"I was thinking of writing to you to-day, when your note with the Orchids came. What frightful trouble you have taken about Vanilla; you really must not take an atom more; for the Orchids are more play than real work.