PSYCHICAL EVOLUTION 133 



grasses, but which is now a pure waste of time. 

 Darwin records it as a fact, that he has himself 

 seen a simple-minded dog turn round twenty times 

 before lying down. The sheep-killing mania, 

 which sometimes comes over dogs when three or 

 four of them get together and become actuated by 

 the ' mob ' spirit, is a vestige of the old instihct of 

 the carnivore which centuries of domestication 

 have not yet quite erased. Goodness, if too 

 prolonged, becomes irksome to dogs for the same 

 reason that it does to men. Dogs have come 

 from savages just as men have, and, while the 

 civilised nature of the dog is more constitutional 

 than that of civilised man, the old deposed instincts 

 mount to the throne once in awhile, and the faith- 

 ful collie is for the time being a wolf again. The 

 instinct of domestic sheep to imitate their leader 

 in leaping over obstacles is another probable 

 survival of wild life. If a bar or other obstacle 

 be placed where the leader of a flock of sheep is 

 compelled to leap over it, and the obstacle is then 

 removed, the entire band of followers will leap at 

 the same place regardless of the fact that the 

 obstruction is no longer there. No other animals 

 do this. The instinct is probably a survival of 

 wild life, when these animals, pursued by their 

 enemies over chasms and precipices, were com- 

 pelled to imitate in the flight those in front of 

 them in order to live. Darwin thinks the donkey 

 shows its aboriginal desert nature in its aversion 

 for crossing the smallest stream, and its relish for 

 rolling in the dust. The same aversion for every- 



