LETTER 733. TO G.J. ROMANES.

(733/1. Published in the "Life of Romanes," page 62.)

Down, August 10th [1877].

When I went yesterday I had not received to-day's "Nature," and I thought that your lecture was finished. (733/2. Abstract of a lecture on "Evolution of Nerves and Nervo-Systems," delivered at the Royal Institution, May 25th, 1877. "Nature," July 19th, August 2nd, August 9th, 1877.) This final part is one of the grandest essays which I ever read.

It was very foolish of me to demur to your lines of conveyance like the threads in muslin (733/3. "Nature," August 2nd, page 271.), knowing how you have considered the subject: but still I must confess I cannot feel quite easy. Everyone, I suppose, thinks on what he has himself seen, and with Drosera, a bit of meat put on any one gland on its disc causes all the surrounding tentacles to bend to this point, and here there can hardly be differentiated lines of conveyance. It seems to me that the tentacles probably bend to that point wherever a molecular wave strikes them, which passes through the cellular tissue with equal ease in all directions in this particular case. (733/4. Speaking generally, the transmission takes place more readily in the longitudinal direction than across the leaf: see "Insectivorous Plants," page 239.) But what a fine case that of the Aurelia is! (733/5. Aurelia aurita, one of the medusae. "Nature," pages 269-71.)