98 HOMO V. DARWIN. 



animals, it is impossible to catch many in the same place, 

 and in the same kind of trap, or to destroy them by the 

 same kind of poison ; yet it is improbable that all should 

 have partaken of the poison, and impossible that all should 

 have been caught in the trap. They must learn caution by 

 seeing their brethren caught or poisoned. . . If we look to 

 successive generations, or to the race, there is no doubt 

 that birds and other animals gradually both acquire, and 

 lose, caution in relation to man or other enemies ; and this 

 caution is certainly, in chief part, an inherited habit or 

 instinct, but, in part, the result of individual experience. 

 . . . Our domestic dogs . . . have progressed in certain 

 moral qualities, such as aifection, trustworthiness, temper, 

 and probably in general intelligence. The common rat has 

 conquered and beaten several other species throughout 

 Europe, in parts of North America, New Zealand, and 

 recently in Formosa, as well as on the mainland of China. 

 Mr. Swinhoe, who describes these latter cases, attributes the 

 victory of the common rat to its superior cunning ; and this 

 latter quality may be attributed to the habitual exercise of 

 all its faculties in avoiding extirpation by man, as well as 

 to nearly all the less cunning or weak-minded rats having 

 been successively destroyed by him. To maintain, inde- 

 pendently of any direct evidence, that no animal, during 

 the course of ages, has progressed in intellect, or other 

 mental faculties, is to beg the question of the evolution of 

 species." (Vol. i. pp. 49, 51.) 



Lord G. It may be quite true, Mr. Darwin, that the 

 instinct of self-preservation in birds, and rats, and other 

 animals, may become more or less keen as it is more or less 

 exercised, but you surely cannot mean that this circumstance 

 shows them to be capable of indefinite improvement, and to 

 possess the same kind of mental powers that man possesses 



