Whenever we meet (which will be on the 23rd [at the] Club) I shall much like to hear whether this strikes you as sound. I feel all the time on the borders of a circle of truism. Of course I could not think of such a request, but you might possibly:--if Bentham does not think the whole subject rubbish, ask him some time to pick out the dozen most anomalous genera in the Leguminosae, or any great order of which there is a monograph by which I could calculate the ordinary percentage of species to genera. I am the more anxious, as the more I enquire, the fewer are the cases in which it can be done. It cannot be done in birds, or, I fear, in mammifers. I doubt much whether in any other class of insects [other than Curculionidae].
I saw your nice notice of poor Forbes in the "Gardeners' Chronicle," and I see in the "Athenaeum" a notice of meeting on last Saturday of his friends. Of course I shall wish to subscribe as soon as possible to any memorial...
I have just been testing practically what disuse does in reducing parts. I have made [skeletons] of wild and tame duck (oh the smell of well-boiled, high duck!), and I find the tame duck ought, according to scale of wild prototype, to have its two wings 360 grains in weight; but it has only 317, or 43 grains too little, or 1/7 of [its] own two wings too little in weight. This seems rather interesting to me. (43/2. On the conclusions drawn from these researches, see Mr. Platt Ball, "The Effects of Use and Disuse" (Nature Series), 1890, page 55. With regard to his pigeons, Darwin wrote, in November 1855: "I love them to that extent that I cannot bear to kill and skeletonise them.")
P.S.--I do not know whether you will think this worth reading over. I have worked it out since writing my letter, and tabulate the whole.
21 orders with 1 genus, having 7.95 species (or 4.6?).
29 orders with 2 genera, having 15.05 species on an average.
23 orders each with 3 genera, and these genera include on an average 8.2 species.
20 orders each with 4 genera, and these genera include on an average 12.2 species.
27 orders each with above 50 genera (altogether 4716 genera), and these genera on an average have 9.97 species.
From this I conclude, whether there be many or few genera in an order, the number of species in a genus is not much affected; but perhaps when [there is] only one genus in an order it will be affected, and this will depend whether the [genus] Erythroxylon be made a family of.
LETTER 44. TO J.D. HOOKER. Down, April 8th .
I have been particularly glad to get your splendid eloge of Lindley. His name had been lately passing through my head, and I had hoped that Miers would have proposed him for the Royal medal. I most entirely agree that the Copley (44/1. The late Professor Lindley never attained the honour of the Copley medal. The Royal medal was awarded to him in 1857.) is more appropriate, and I daresay he would not have valued the Royal. From skimming through many botanical books, and from often consulting the "Vegetable Kingdom," I had (ignorant as I am) formed the highest opinion of his claims as a botanist. If Sharpey will stick up strong for him, we should have some chance; but the natural sciences are but feebly represented in the Council. Sir P. Egerton, I daresay, would be strong for him. You know Bell is out. Now, my only doubt is, and I hope that you will consider this, that the natural sciences being weak on the Council, and (I fancy) the most powerful man in the Council, Col. S[abine], being strong against Lindley, whether we should have any chance of succeeding. It would be so easy to name some eminent man whose name would be well-known to all the physicists. Would Lindley hear of and dislike being proposed for the Copley and not succeeding? Would it not be better on this view to propose him for the Royal? Do think of this. Moreover, if Lindley is not proposed for the Royal, I fear both Royal medals would go [to] physicists; for I, for one, should not like to propose another zoologist, though Hancock would be a very good man, and I fancy there would be a feeling against medals to two botanists.