If you have time I think a rather hopeless experiment would be worth trying; anyhow, I should have tried it had my health permitted.

It is to insert a minute grain of some organic substance, together with the poison from bees, sand-wasps, ichneumons, adders, and even alkaloid poisons into the tissues of fitting plants for the chance of monstrous growths being produced.
(177/2.

See "Life and Letters," III., page 346, for an account of experiments attempted in this direction by Mr.Darwin in 1880.

On the effects of injuring plant-tissues, see Massart, "La Cicatrisation, etc." in Tome LVII.

of the "Memoires Couronnes" of the Brussels Academy.) My health has long been poor, and I have lately suffered from a long illness which has interrupted all work, but I am now recommencing a volume in connection with the "Origin." P.S .-- If you write again I should very much like to hear what your life in your new country is.
What can be the meaning or use of the great diversity of the external generative organs in your cases, in Bombus, and the phytophagous coleoptera?
What can there be in the act of copulation necessitating such complex and diversified apparatus?
LETTER 178.