EMOTIONS. 351 



Next we arrive at Birds with the psychological distinc- 

 tion of recognizing pictorial representations, understanding 

 words, and dreaming.* If any of these faculties occur in 

 any of the lower vertebrata, I have not found evidence of 

 the fact. 



To the next level I have assigned the Eodents and Carni- 

 vora, with the exception of the dog. The most marked 

 psychological distinction which I take to mark this level is 

 the understanding of mechanisms. For, although I have 

 found one instance of such understanding to occur in Birds,t 

 and although it likewise unquestionably occurs in Eumi- 

 nants,J in neither case does the understanding appear to 

 extend further than to the simplest order of mechanisms, and 

 therefore is only comparable in kind with the much greater 

 aptitude in this respect which is shown by rats,§ foxes,|| 

 cats,1[ and the wolverine.** 



* Animal Intelligence, pp. 311-12. f Ihid., p. 316. % Ihid., pp. 338-9. 



§ Ihid., p. 361. II Ihid., pp. 428-31. ^ Ihid., pp. 420-22. 



** Ihid., pp. 348-50. — Sir James Paget lias told me of a parrot wliicli by 

 attentive study learned how to open a lock ; but altliougli sucli eases may 

 occasionally occur in birds, they are so comparatively rare that I have thought 

 it best to place the faculty of appreciating simple mechanical appliances on 

 the next level, for it is here only that we may first be sure that the actions 

 are not due to mere association. A cat which jumps at a thumb-latch, and 

 while holding on to the curved handle beneath with one fore-leg, depresses the 

 thumb-piece with the other and pushes the door-posts with the hind-leg, 

 clearly shows that she has an intelligent appreciation of the facts that the 

 latch fastens the door, that when it is depressed the door will be liberated, 

 and that when then pushed the door will open. And if it can still be sup- 

 posed that all this knowledge can be obtained by simple association, there 

 is the yet more remarkable case of the monkey described in Animal Intelli- 

 gence, which by patient investigation discovered for himself, and without ever 

 having observed any one perfonn a similar action, the mechanical principle 

 of the screw, not to say also of the lever. 



It is remarkable, as I observed in Animal Intelligence, that this faculty 

 of appreciating simple mechanical appliances does not seem always to stand 

 in any very precise or quantitative relation to the general mental develop- 

 ment of the species which exhibit it. Thus the dog is, as to his general in- 

 telligence, unquestionably superior to the cat, and yet his ability in the 

 particular we are considering is certainly not so high ; while bovine animals 

 and horses seem to show more cleverness in this respect than in any other. 

 Probably the explanation of this apparent disproportion in the development 

 of the psychical facvdties is to be found in the corporeal members which 

 minister to them ; the monkey, which shows the highest power of appreciating 

 mechanical appliances, is the animal which is best endowed with the organs 

 of tactual examination ; the fore -paws of a cat are better instruments in this 

 respect than those of the dog ; while the trvmk of the elephant, the lips of 

 the horse, and horns of ruminants give them in the same respects an advantage 

 over most other mammals of a comparable grade of intelligence. 



