My dear M^r Oliver

I am heartily glad to hear that the Professorship is properly decided.—³

I have been glad to see the slide, but I am sorry to say the glass arrived cracked. I do not think that the structure is so plain as when I made fresh slices. I shall be some time curious to know what you see so remarkable in the sensitive Hairs.—   I hope some day you will study the Dionæa & publish on it. I shall make only a few remarks in comparison with Drosera.⁴ I can see nothing in Sensitive Hairs more than I saw before, viz elongated cells arranged spirally with a bifid point, with no spiral vessel or stomata.— There is a short footstalk making change of structure in cells & that is all I can see! I conjecture that the sensitive Hairs are homologous with the tortoise-shells or buttons, in a much elongated condition.—   I cannot help fancying that by holding footstalk of living leaf & retarding the movement by your thumb with good lens, you could see whether the sensitive Hair became mottled in colour by touching it with needle. (I can tell with Lens whether Hairs of Drosera are mottled.) It ought to do so!!—   I shall be intensely curious to hear about C. of Ammonia & Dionæa.—⁵

I have tried several salts on the Hairs & Roots of Drosera & on other plants.⁶ But I know well I have not tried enough; nor intend to do so for the work is quite out of my line; & though I have enjoyed it very much, I have been exceedingly foolish to attempt it. I still think the action of the Carbonate & some other salts of Ammonia remarkable. & worth any one’s following out.—   I shall briefly give the facts in my paper.— I put all the roots of a little plant of Euphorbia in water with $\frac{1}{8}$ ^th of grain of C. of Ammonia, & it was curious how it wholly altered the appearance of every cell in all the roots.—⁷ The action is so rapid, that you cannot put the root under the microscope, before clouds of granules have shot some way up the roots.—

Now I am going to beg a little favour of you—   Does not M^r Fitch work at Kew?⁸ And will he draw for anyone for payment? If he will be so good as to make 2 or 3 drawings for me, I sh^d be very much obliged & I could repay by P. order.

First, a leaf of Drosera with all the Hairs fully expanded. It is for woodcut for any reader who is not a Botanist. It ought to be 3 or 4 times natural size. M^r F. could judge this. It ought to be done neatly.— The extreme marginal Hairs are long-headed; whether on this scale the difference could be represented, I know not.—

Secondly would you put little fly on exact middle of leaf, & after Hairs are well clasped get a drawing made on same scale.

Thirdly, perhaps, sketch of leaf of Dionæa, just to interest Reders.⁹ I shall have copied from Trécul the minute structure of Hairs.—¹⁰

My dear Sir | Yours very sincerely | C. Darwin