152 THE PEESIDENCY OF THE KOYAL SOCIETY 



mouthful of potato every man pointed it to the herring before 

 eating it — by way of catching a flavor. 



The work on Carnivorous plants was one of those which 

 grew out of Darwin's enquiries. Hooker, as has been said, 

 was constantly supplying his friend with plants for experiment 

 and experimenting for him on plants which could not be kept 

 in the small greenhouse at Down. 



During this period his help lay chiefly among the sensi- 

 tive and the carnivorous plants. As to the former, Hooker 

 occasionally experimented ; thus in November, 1873, 



I was trying Mimosa albida in the Hot -house the other 

 day and found it wonderfully sensitive compared to what 

 it was in my room. I wonder if the damp heat kept it on 

 the * qui vive,' like a pig before rain ! It is in our hottest 

 house now. 



But his chief part was to send plants and answer questions, 

 which sometimes were liable to be pushed home with searching 

 supplementary questions for which he had perhaps a practical 

 but not a scientific answer. 



Thus in 1873 (as later in 1877) Darwin sought some explana- 

 tion of the waxy coat or ' bloom ' and layer of fine hairs upon 

 leaves. (See CD. iii. 339, and M.L. ii. 409, 410.) One obvious 

 effect of these equipments was to keep water off. But was 

 this all ? 



To Charles Darwin 



August 14, 1873. 



I have often speculated on the point you allude to, 

 which is specially conspicuous in the Nelumbium. Ferns 

 and various Cryptogams do not show it as Phaenogams do. 

 It is not conspicuous in other water plants as in Nelumbium, 

 which further holds its leaves high above the water ; — but 

 for this association of the two means of getting out of the 

 way as it were of injury from the water, I should have 

 supposed that both waxy coat and hairs were connected 

 with absorption in respiratory functions. I have lately 

 wondered whether both may not subserve some purpose 

 connected with Actinic or chemical rays of the sun, especially 



