244 MISCELLANEA (continued). [iSSi. 



Thirdly, Dr. Roux has sent me a book just published by 

 him: ' Der Kampf der Theile,' &c., 1881 (240 pages in 

 length). 



He is manifestly a well-read physiologist and pathologist, 

 and from his position a good anatomist. It is full of reason- 

 ing, and this in German is very difficult to me, so that I have 

 only skimmed through each page ; here and there reading 

 with a little more care. As far as I can imperfectly judge, it 

 is the most important book on Evolution which has appeared 

 for some time. I believe that G. H. Lewes hinted at the 

 same fundamental idea, viz. that there is a struggle going on 

 within every organism between the organic molecules, the 

 cells and the organs. I think that his basis is, that every cell 

 which best performs its function is, in consequence, at the same 

 time best nourished and best propagates its kind. The book 

 does not touch on mental phenomena, but there is much 

 discussion on rudimentary or atrophied parts, to which 

 subject you formerly attended. Now if you would like to 

 read this book, I would send it. ... If you read it, and are 

 struck with it (but I may be wholly mistaken about its value), 

 you would do a public service by analysing and criticising it 

 in ' Nature.' 



Dr. Roux makes, I think, a gigantic oversight in never con- 

 sidering plants ; these would simplify the problem for him. 



Fourthly, I do not know whether you will discuss in your 

 book on the mind of animals any of the more complex and 

 wonderful instincts. It is unsatisfactory work, as there can 

 be no fossilised instincts, and the sole guide is their state in 

 other members of the same order, and mere probability. 



But if you do discuss any (and it will perhaps be expected 

 of you), I should think that you could not select a better case 

 than that of the sand wasps, which paralyse their prey, as 

 formerly described by Fabre, in his wonderful paper in the 



* Annales des Sciences,' and since amplified in his admirable 



* Souvenirs.' 



