LETTER 726. TO J.D. HOOKER. Down, August 30th [1874].

I am particularly obliged for your address. (726/1. Presidential address (Biological Section) at the Belfast meeting of the British Association, 1874.) It strikes me as quite excellent, and has interested me in the highest degree. Nor is this due to my having worked at the subject, for I feel sure that I should have been just as much struck, perhaps more so, if I had known nothing about it. You could not, in my opinion, have put the case better. There are several lights (besides the facts) in your essay new to me, and you have greatly honoured me. I heartily congratulate you on so splendid a piece of work. There is a misprint at page 7, Mitschke for Nitschke. There is a partial error at page 8, where you say that Drosera is nearly indifferent to organic substances. This is much too strong, though they do act less efficiently than organic with soluble nitrogenous matter; but the chief difference is in the widely different period of subsequent re-expansion. Thirdly, I did not suggest to Sanderson his electrical experiments, though, no doubt, my remarks led to his thinking of them.

Now for your letter: you are very generous about Dionoea, but some of my experiments will require cutting off leaves, and therefore injuring plants. I could not write to Lady Dorothy [Nevill]. Rollisson says that they expect soon a lot from America. If Dionoea is not despatched, have marked on address, "to be forwarded by foot-messenger."

Mrs. Barber's paper is very curious, and ought to be published (726/2. Mrs. Barber's paper on the pupa of Papilio Nireus assuming different tints corresponding to the objects to which it was attached, was communicated by Mr. Darwin to the "Trans. Entomolog. Soc." 1874.); but when you come here (and REMEMBER YOU OFFERED TO COME) we will consult where to send it. Let me hear when you recommence on Cephalotus or Sarracenia, as I think I am now on right track about Utricularia, after wasting several weeks in fruitless trials and observations. The negative work takes five times more time than the positive.