Oh. XVII] INSECTIVOROUS PLANTS. 321 



Heaven knows whether I shall ever publish my pile of experi- 

 ments on it." 



He notes in his diary that the last proof of the Expression 

 of the Emotions was finished on August 22, 1872, and that he 

 began to work on Drosera on the following day. 



C. D. to Asa Gray [Sevenoaks], October 22 [1872]. 



... I have worked pretty hard for four or five weeks on 

 Drosera, and then broke down ; so that we took a house near 

 Sevenoaks for three weeks (where I now am) to get complete 

 rest. I have very little power of working now, and must put 

 off the rest of the work on Drosera till next spring, as my 

 plants are dying. It is an endless subject, and I must cut it 

 short, and for this reason shall not do much on Dionroa. The 

 point which has interested me most is tracing the nerves ! 

 which follow the vascular bundles. By a prick with a sharp 

 lancet at a certain point, I can paralyse one-half the leaf, 60 

 that a stimulus to the other half causes no movement. It is 

 just like dividing the spinal marrow of a frog : — no stimulus 

 can be sent from the brain or anterior part of the spine to the 

 hind legs: but if these latter are stimulated, they move by 

 reflex action. I find my old results about the astonishing 

 sensitiveness of the nervous system (I ?) of Drosera to various 

 stimulants fully confirmed and extended. . . . 



G. B. to Asa Gray, Down, June 3 [1874]. 



... I am now hard at work getting my book on Drosera & Co. 

 ready for the printers, but it will take some time, for I am 

 always finding out new points to observe. I think you will 

 be interested by my observations on the digestive process 

 in Drosera ; the secretion contains an acid of the acetic series, 

 and some ferment closely analogous to, but not identical with, 

 pepsine ; for I have been making a long series of comparative 

 trials. No human being will believe what I shall publish 

 about the smallnessof the doses of phosphate of ammonia which 

 act 



The manuscript of Insectivorous Plants was finished in 

 March 1875. He seems to have been more than usually 

 oppressed by the writing of this book, thus he wrote to Sir 

 J. D. Hooker in February : — 



" You ask about my book, and all that I can say is that I am 

 ready to commit suicide ; I thought it was decently written, 



Y 



