1881 EESEAECH ON ECHINODEEilS 99 



few days to refer to when the proof which I have 

 sent to press shall be returned with ray 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 pedicellariae in a 

 wonderful manner. 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 

 estabUsh their adhesions, so assisting locomotion of 

 animal when crawling about seaweed-covered rocks. 



November 5, 1880. 



I was sorry to hear on my return from Scotland 

 that I had missed the pleasure of a call from you, 

 and also to hear from Mr. Teesdale to-day that you 

 had returned to Down, owing, he fears, to the alarm- 

 ing condition of Miss Wedgwood. I trust, however, 

 that her state of health may not be so serious as he 

 apprehends. 



On my way South I stayed for a couple of days 

 at Newcastle, to give two lectures on Mental Evolu- 

 tion, and hence my absence when you called. I 

 stayed vrith Mr. NewaU, who has the monster tele- 

 scope, and ' as good luck would have it, Pi-ovidence 

 was on my side,' in the matter of gi'V'ing us a clear 

 sky for observing, rather a rare thing at Newcastle. 



H 2 



