INTRODUCTORY 1 5 



duct of individual animals of the same species, it is clear that 

 even if we believe that sufficient knowledge of their nature would 

 enable us to predict their conduct, this knowledge is unattainable, 

 for we cannot possibly know all the complicated personal history 

 of any one animal. We must also remember that even if we 

 prove that individual animals acquire, by contact with the ex- 

 ternal world, nothing but what their nature provides for, this 

 does not show that they are compelled to make of themselves all 

 that their nature permits, for the effects of experience are often 

 injurious or destructive. There is, unfortunately, no incompati- 

 bility between the system of things and unprofitable experience, 

 for it is, to say the least, no harder to corrupt or injure nature by 

 injudicious or pernicious training than it is to make the best of it. 



Romanes tells us (" Mental Evolution in Animals," p. 215) of a 

 hen that had reared three successive broods of ducklings in suc- 

 cessive years, and then hatched out a brood of nine chickens : 

 " The first day she was let out she disappeared, and after a long 

 search my sister," his informant writes, "found her beside a little 

 stream, which her successive broods of ducklings had been in the 

 habit of frequenting. She had got four of her chickens into the 

 water, which, fortunately, was very shallow at the time. The other 

 five were all standing on its margin, and she was endeavoring by 

 all sorts of coaxing hen-language, and by pushing each chicken 

 in turn with her bill, to get them into the water also." 



In the normal course of the history of chicks, the response to 

 the order of nature which experience is said to have called out 

 in this hen, would be rapidly fatal to her posterity ; and it would 

 be easy to give other illustrations to show that the changes which 

 are called forth in living things by the influence of the world 

 around them, are beneficial only so far as this external world is, 

 on the average, substantially the same as that to which the actions 

 of their ancestors were adjusted. The snake that swallows hens' 

 eggs, like its ancestors, profits like them ; but the snake that 

 swallows a china nest-egg dies from indigestion. I shall try to 

 show that this fact, and others like it, mean that while the changes 

 would not take place without practice or training, their character 

 is due to nature, and not to experience. 



It is almost impossible to contemplate the actions of animals 



