to carry down the pollinia, taken from one flower on the point of a fine needle, to the stigma of another flower, have failed,—the pollinia lodging above the stigma or over on the dorsal face.² I enclose a spike of S. cernua.

Sept. 2^d. That Drosera filiformis should show no sensitiveness is perhaps not remarkable, for it is not well arranged for fly-catching.³ But I have got some D. rotundifolia, & tried it with atoms of fresh fish laid on the viscid tips, but I could detect no movement either immediate or later. Yet I could see that some of the leaves had their bristles turned inwards and had been catching flies. I have been to-day into the country and have brought in some fres⁠⟨⁠h⁠⟩⁠ D. rotundifolia, to try again to-morrow.

The most marked diœcio-dimorphous flowers I know are in Rubiaceæ, and the most familiar cases are in Houstonia (Oldenlandia, but the old name & genus will be restored) specially our H. purpurea and the everywhere common H. cærulea, and Mitchella repens. Spermacoce virginiana & Diodia teres, also show it. I have no data for a list; but the cases are numerous. I will make any observations you will indicate next spring.⁴

What you say of Mill well accords with what Prof. Henry of Smithsonian Instⁿ. says of your investigations., your method, &c,—and he is the best judge of the logic of investigation I know of.⁵