Very many thanks for your kind assistance and expressions of approval.¹ It was stupid of me to forget your article in ‘Nature’ about the geese.² I now quite well remember reading it when it came out.

Focke’s book is just the very thing I wanted, as it supplies such a complete history of the subject.³ If I do not hear from you again, I shall keep it for a few days to refer to when the proof which I have sent to press shall be returned with my historical sketch added.

I have now nearly finished my paper on the physiology of the locomotor system in Echinoderms. The most important result in it is the proof, both morphological and physiological, of a nervous plexus, external to everything, which in Echinus serves to co-ordinate spines, feet, and pedicellariæ in a wonderful manner.⁴ By the way, I remember once talking with you about the function of the latter, and thinking it mysterious. There is no doubt now that this function is to seize bits of seaweed, and hold them steady till the sucking feet have time to establish their adhesions, so assisting locomotion of animal when crawling about seaweed-covered rocks.