eir diurnal
horizontal position. As the leaflets are alternate, and as the upper
surface will be somewhat exposed to the dawning light, it is perhaps
diaheliotropism which explains your extraordinary case.

LETTER 689. TO F. MULLER. Down, April 12th, 1881.

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 an