Dear Sir,

I venture to mention a fact which came under my notice lately, while staying at a Thames-side Inn, and which may possibly interest you.

A young friend of mine, bent on fishing, (August) took a clean earthen pot, & having neither moss nor grass, put in it a handful of the first green weed he found in the kitchen garden. In half an hour or so he collected about 100 worms and brought them for me to look at. On taking out the weed I found, at the bottom, a clotted mass of worms all dead—not a single one showed sign of life. The intestines were emptied, & death had apparently been convulsive, for in most cases the anal rings were everted and distended. A glance revealed the cause. The weed was common spurge,¹ crushed & damp, for the day was wet, but the main stems were little broken, so the amount of milky juice exuded must have been small in quantity. I, at once, got a few fresh worms, & a plant or two of spurge, and found that a single small drop placed on a worm seemed instantly to paralyze the rings behind the drop. Another touch or two was fatal in five or six minutes to most individuals, but some resisted longer. All, however, died.

I carelessly forgot to examine the ground in order to ascertain whether burrows or casts existed where spurge grows in any plenty. My own little garden here has, unluckily, been carefully weeded. I ought to have satisfied myself on this point, and also to have ascertained whether spurge is ever used by worms. Probably the euphorbic poison is eliminated by decay, or internally it may be harmless to them, as the common scale insects² sucks not only holly, bamboo, camellia, and orange, but the deadly oleander. Nerium juice³ I find by experiment is as fatal to worms as spurge juice, but in action it appears somewhat to differ. The operation of vegetable poisons on the leaf eating annelidae & molluscs would seem to afford many questions of interest.

Begging you to excuse the liberty I have taken as a stranger (though a very old disciple) in writing to you, | I remain, D^r. Sir | Y^r. very obed^t. Ser^t. | Fred^k. Capes

C. Darwin Esq^r. LLD. F.RS. | Down | Bickley