i874.] CLIMBING AND INSECTIVOROUS PLANTS. 497 



C. Darwin to W. Thiselio7i Dyer. 



Down, 24 [December 1873?] 



My dear Mr. Dyer, — I fear that you will think me a 



•great bore, but I cannot resist telling you that I have just 



found out that the leaves of Pinguicula possess a beautifully 



adapted power of movement. Last night I put on a row of 



little flies near one edge of two yowigish leaves ; and after 14 



hours these edges are beautifully folded over so as to clasp 



the flies, thus bringing the glands into contact with the upper 



surfaces of the flies, and they are now secreting copiously 



above and below the flies and no doubt absorbing. The acid 



secretion has run down the channelled edge and has collected 



in the spoon-shaped extremity, where no doubt the glands 



are absorbing the delicious soup. The leaf on one side looks 



just like the helix of a human ear, if you were to stuff flies 



within the fold. Yours most sincerely, 



Ch. Darwin. 



C. Darwift to Asa Gray. 



Down, June 3 [1874]. 



.... I am now hard at work getting my book on Dro- 

 sera & 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, pepsin ; for I have been making a long series 

 of comparative trials. No human being will believe what I 

 shall publish about the smallness of the doses of phosphate 

 of ammonia which act. 



.... I began reading the Madagascar squib * quite 

 gravely, and when I found it stated that Felis and Bos in- 

 habited Madagascar, I thought it was a false story, and did 

 not perceive it was a hoax till I came to the woman. . . . 



* A description of a carnivorous plant supposed to subsist on human 

 beings. 



