108 GEOEGE JOHN ROMANES isso- 



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 

 establish their adhesions, so assisting locomotion of 

 animal when crawling about seaweed-covered rocks. 



From G. J. Eomanes to C. Darwin, Esq. 



18 Cornwall Terrace, Regent's Park, N.W. : December 10, 1880. 



I return by this post the book on Hybridism, 

 with many thanks. It itas been of great use to me 

 in giving an abstract of the history. 



I have read your own book with an amount of 

 pleasure that I cannot express. 



One idea occurred to me with reference to lumi- 

 nous stimulation, which, if it has not already occurred 

 to you, would be well worth trying. The suggestion 

 suggests itself. How about the period of latent stimu- 

 lation in these non-nervous and yet irritable tissues ? 

 And especially with reference to luminous stimulation 

 it would be most interesting to ascertain whether the 

 tissues are affected by brief flashes of light. If you 

 had an apparatus to give bright electrical sparks in a 

 dark room, and were to expose one of your plants to 

 flashes of timed intervals between each other, you 

 might ascertain, first, whether any number of sparks 

 in any length of time would affect the plants at all ; 

 and second, if so, what number in a given time. I 

 should not wonder (from some of my experiments on 



