1 88 1.] ANIMAL INTELLIGENCE. 245 



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 p. 241) on the lower and softest side of the body — and 

 that to sting a certain segment was found by far the most 

 successful method ; and was inherited like the tendency of a 

 bulldog to pin the nose of a bull, or of a ferret to bite the 

 cerebellum. It would not be a very great step in advance to 

 prick the ganglion of its prey only slightly, and thus to give 

 its larvae fresh meat instead of old dried meat. Though 

 Fabre insists so strongly on the unvarying character of 

 instinct, yet it is shown that there is some variability, as at 

 p. 176, 177. 



I fear that I shall have utterly wearied you with my 

 scribbling and bad handwriting. 



My dear Romanes, yours very sincerely, 



Ch. Darwin. 



Postscript of a Letter to Professor A. Agassiz, May $t/i, 



1881 :— 



"I read with much interest your address before the American 

 Association. However true your remarks on the genealogies 

 of the several groups may be, I hope and believe that you 

 have over-estimated the difficulties to be encountered in the 

 future : — A few days after reading your address, I interpreted 



