My dear M^r Vines

I write just to say that the rows of cells with granular matter after C. of Ammonia are exhibited as well by the white & young rootlets of the common zonal Pelargonium, as by Euphorbia.¹ There is a slight difference that 2, 3, 4 or 5 rows with granular matter often adjoin one other. There are, also, long cells & I think tubes with coarser granular matter round & amidst the vascular bundle. So I was altogether wrong in supposing that these rows of cells were indirectly connected with the laticiferous ducts. But I have observed a fact today & yesterday with the Pelargonium (whether it will hold with Euphorbia I do not yet know) which seems to me remarkable, viz that the root-hairs arise exclusively from the rows of cells which are not acted on by the C. of Ammonia & which do not contain the brownish granular matter.² It appears,, therefore, that certain rows of cells with hairs act as absorbant, & that the adjoining rows act for elaborating or storing matter of some kind. This is to me is a new view of the structure & function of rootlets, & I sh^d. like to hear whether you know of anything of the kind. I traced 50 root-hairs to colourless cells & did not see one arising from the cells with granular matter; & this seemed sufficient evidence; but I must keep my eyes open for I am always blundering.—

Yours very sincerely | Ch. Darwin

My son Frank will return home from salmon-fishing in a few days³ & he will then make the salt-solution, which I will try, as you recommend, though I do not know object.—⁴

I work with No’ 8. of Hartnack, sometimes looking with next lower power.⁵