Chapter 353

I have delayed answering your last letter of February 25th, as I was just sending to the printers the MS. of a very little book on the habits of earthworms, of which I will of course send you a copy when published. I have been very much interested by your new facts on paraheliotropism, as I think that they justify my giving a name to this kind of movement, about which I long doubted. I have this morning drawn up an account of your observations, which I will send in a few days to "Nature." (689/1. "Nature," 1881, page 603. Curious facts are given on the movements of Cassia, Phyllanthus, sp., Desmodium sp. Cassia takes up a sunlight position unlike its own characteristic night-position, but resembling rather that of Haematoxylon (see "Power of Movement," figure 153, page 369). One species of Phyllanthus takes up in sunshine the nyctitropic attitude of another species. And the same sort of relation occurs in the genus Bauhinia.) I have thought that you would not object to my giving precedence to paraheliotropism, which has been so little noticed. I will send you a copy of "Nature" when published. I am glad that I was not in too great a hurry in publishing about Lagerstroemia. (689/2. Lagerstraemia was doubtfully placed among the heterostyled plants ("Forms of Flowers," page 167). F. Muller's observations showed that a totally different interpretation of the two sizes of stamen is possible. Namely, that one set serves merely to attract pollen-collecting bees, who in the act of visiting the flowers transfer the pollen of the longer stamens to other flowers. A case of this sort in Heeria, a Melastomad, was described by Muller ("Nature," August 4th, 1881, page 308), and the view was applied to the cases of Lagerstroemia and Heteranthera at a later date ("Nature," 1883, page 364). See Letters 620-30.) I have procured some plants of Melastomaceae, but I fear that they will not flower for two years, and I may be in my grave before I can repeat my trials. As far as I can imperfectly judge from my observations, the difference in colour of the anthers in this family depends on one set of anthers being partially aborted. I wrote to Kew to get plants with differently coloured anthers, but I learnt very little, as describers of dried plants do not attend to such points. I have, however, sowed seeds of two kinds, suggested to me as probable. I have, therefore, been extremely glad to receive the seeds of Heteranthera reniformis. As far as I can make out it is an aquatic plant; and whether I shall succeed in getting it to flower is doubtful. Will you be so kind as to send me a postcard telling me in what kind of station it grows. In the course of next autumn or winter, I think that I shall put together my notes (if they seem worth publishing) on the use or meaning of "bloom" (689/3. See Letters 736-40.), or the waxy secretion which makes some leaves glaucous. I think that I told you that my experiments had led me to suspect that the movement of the leaves of Mimosa, Desmodium and Cassia, when shaken and syringed, was to shoot off the drops of water. If you are caught in heavy rain, I should be very much obliged if you would keep this notion in your mind, and look to the position of such leaves. You have such wonderful powers of observation that your opinion would be more valued by me than that of any other man. I have among my notes one letter from you on the subject, but I forget its purport. I hope, also, that you may be led to follow up your very ingenious and novel view on the two-coloured anthers or pollen, and observe which kind is most gathered by bees.