2l6 EVOLUTION [CHAP. Ill 



Letter 149 requires some pushing, so that if you do not wish these 

 lectures to be extensively circulated, I suppose they will not ; 

 otherwise I should think they would do good and spread a 

 taste for the natural sciences. Anyhow, I have liked them ; 

 but I get more and more, I am sorry to say, to care for 

 nothing but Natural History ; and chiefly, as you once said, 

 for the mere species question. I think I liked No. III. the 

 best of all. I have often said and thought that the process of 

 scientific discovery was identical with everyday thought, only 

 with more care ; but I never succeeded in putting the case to 

 myself with one-tenth of the clearness with which you have 

 done. I think your second geological section will puzzle your 

 non-scientific readers ; anyhow, it has puzzled me, and with 

 the strong middle line, which must represent either a line of 

 stratification or some great mineralogical change, I cannot 

 conceive how your statement can hold good. 



I am very glad to hear of your " three-year-old ' 

 vigour [?] ; but I fear, with all your multifarious work, that 

 your book on Man will necessarily be delayed. You bad 

 man ; you say not a word about Mrs. Huxley, of whom my 

 wife and self are always truly anxious to hear. 



P.S. I see in the Cornhill Magazine a notice of a work 

 by Cohn, which apparently is important, on the contractile 

 tissue of plants. 1 You ought to have it reviewed. I have 

 ordered it, and must try and make out, if I can, some of the 

 accursed german, for I am much interested in the subject, 

 and experimented a little on it this summer, and came to 

 the conclusion that plants must contain some substance most 

 closely analogous to the supposed diffused nervous matter 

 in the lower animals ; or as, I presume, it would be more 

 accurate to say with Cohn, that they have contractile tissue. 



Lecture VI., p. 151, line 7 from top wetting feet' 2 ' or 

 bodies ? (Miss Henrietta Darwin's criticism.) 



1 "Ueber contractile Gewebe im Pflanzenreiche." A b hand, der 

 Schlesischen Gesellschaft fiir vaterlandische Cultur, Heft I., 1861. 



2 Lecture VI., p. 151 : Lamarck "said, for example, that the short- 

 legged birds, which live on fish, had been converted into the long-legged 

 waders by desiring to get the fish without wetting their feet." 



The criticisms on Lectures IV. and VI. are on a separate piece of 

 undated paper, and must belong to a letter of later date ; only three 

 lectures were published by Dec. 7th, 1862. 



