420 MISCELLANEA. 



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 sub- 

 ject 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 

 considering 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.' 



Whilst reading this latter book, I speculated a little on the 

 subject. Astonishing nonsense is often spoken of the sand 

 wasp's knowledge of anatomy. Now will any one say that 

 the Gauchos on the plains of La Plata have such knowledge, 

 yet I have often seen them pith a struggling and lassoed cow 

 on the ground with unerring skill, which no mere anatomist 

 could imitate. The pointed knife was infallibly driven in 

 between the vertebrae by a single slight thrust. I presume 

 that the art was first discovered by chance, and that each 

 young Gaucho sees exactly how the others do it, and then 

 with a very little practice learns the art. Now I suppose that 

 the sand wasps originally merely killed their prey by stinging 

 them in many places (see p. 129 of Fabre's 'Souvenirs,' and 



