Darwin Correspondence Project

Down Bromley Kent

Nov 16th

My dear Mr Oliver

In writing out my paper yesterday I was so astounded at my results that I have got fairly frightened, & have determined to finish my paper, but to publish nothing until next summer    I shall have retested my results & tried some of them in another way: so that there is no hurry about the Drawings. If there are good specimens, I shd be glad for Mr Fitch to complete them; otherwise will you ask him to wait till next spring or summer.—

Most heartily do I thank you for your most kind & valuable assistance.— If I could get one or two plants of Dionæa I would experimentise on them; but I shall not of course attempt the anatomy; & if you thought you would undertake the subject, I would not interfere in any way, except by bare allusions to what I have seen; but it is so important to me about the mottling or segregation of colour, that I shd. extremely much wish to ascertain that point, if in the Spring, by the aid of Mr Croker I could purchase (at almost any price) one or two or three of the young plants which he saw.—

I have been corresponding with some of the chemical physiologists & as far as I can find out the curious action of the C. of Ammonia on the roots of plants has not been observed.—

With cordial thanks for all your kindness | My dear Mr Oliver | Yours very sincerely | C. Darwin

P.S. | Can you tell me name of Plant, which grew out of doors in my Fathers garden, 2 to 4 ft high—considerably branched, died down (I think) in winter, bore many minute almost white or very pale pink flowers, & which flowers caught a multitude of flies by their probosces.— I shd. like to get a plant to try to make out final cause of the catching.—

P.S. 2d. | Perhaps you would like to hear following extraordinary fact.— I have placed over & over again minute atoms of paper, stick, cinders meat flies &c on glands of single hairs of Drosera & they always became inflected; so I thought I would test how minute an atom would cause movement: I measured with micrometer several bits of woman's Hair (& thread) which caused movement & found that under 150th of inch amply sufficed. Of same hair I sent 6 inches to be weighed in London by best balance, & it weighed under 1100 of grain, which shows that 1/30,000 of a grain suffices!!

Prolonged pressure alone causes movement.