My dear F.

I have tried your experiment with Cucurbita seeds buried in Peat.— 10 radicles with upper side of apex cauterised & all soon became splendidly geotropic; & 10 on lower side.² Of the latter 4 slightly geotropic—3 remained quite horizontal & 3 bowed upwards, in opposition to Geotropism, & from the cauterised side of apex.— This latter case very good— I also cut off rectangularly 1 m.m of apex of 6 radicles, & they grew much, but did not in 24 h. become at all geotropic.³

I shall try Peas with tips touched above & below with Caustic.⁴

C. D.—

If you can bring home some White Mustard seed, perhaps ours is not right species—⁵

Many thanks for your most interesting letter just received (7th)⁶