My dear Hooker

Having as a wonder no letters to write, I am going to amuse myself by scribbling a few lines to you.— Perhaps you w^d. like to read enclosed on Gunnera: anyhow it need not be returned.² I wonder whether the same explanation can apply to odd little flower in middle, or on axis of umbel of Carrot, which has always been a mystery to me.³ By the way a Melastoma (I know not what or whence) has just flowered in my hot-house, but the 2 sets of stamens do not differ except in size: I have however fertilised a few flowers with pollen from both.⁴

The boys have been observing Stipa, & Horace has made a hygrometer with a bit of the twisted awn or pistil (or whatever it may be) & mounted it on a graduated circle; & I have never in my life been more astonished than at its sensitiveness.⁵ If you blow gently at it from 1 or 2 feet distance, it absorbs moisture & instantly rotates. It is still more surprising that the moisture from a finger held near, not touching, instantly & repeatedly caused a slight movement of about a degree.— What a strong attraction for water the cells must have! We have been disgusted to find in Watts Dict. of Chemistry that some one has used Stipa as a hygrometer.⁶

I have been nicely sold: I saw in a Journal that D^r Pfeiffer gigantic Nomenclator Botanicus is now published, & I assumed that it was like Steudel’s with a list of the species & Habitats, so ordered it.⁷ And now I find it costs ^£12"^s12.0 & that it contains no species,, only genera, & is of not the least use to me or to anyone, except a describer. Would it be real use to Linn. Soc? If so I w^d give it to the Soc. or to any poor working Botanist, or I will ask William & Norgate whether they could sell it for $\frac{1}{2}$ price.⁸ It is folly for me to keep such a book.

Ever yours affecty | C. Darwin