LOGIC OF RECEPTS. 53 



These facts cannot be ascribed to " instinct," seeing that 

 tram-cars could not have been objects of previous experience 

 to the ancestors of the ants ; and therefore the degree of 

 receptual intelHgence, or "practical inference," which was 

 displayed is highly remarkable. Clearly, the insects must 

 have appreciated the nature of these repeated catastrophes, 

 and correctly reasoned out the only way by which they could 

 be avoided. 



As this is an important branch of my subject, I will add 

 a few more illustrations drawn from vertebrated animals, 

 beginning with some from the writings of Leroy, who had 

 more opportunity than most men of studying the habits of 

 animals in a state of nature.* 



He says of the wolf :—"■ When he scents a flock within 

 its fold, memory recalls to him the impression of the shepherd 

 and his dog, and balances that of the immediate neighbour- 

 hood of the sheep ; he measures the height of the fence, 

 compares it with his own strength, takes into account the 

 additional difficulty of jumping it when burdened with his 

 prey, and thence concludes the uselessness of the attempt. 

 Yet he will seize one of a flock scattered over a field, under 

 the very eyes of the shepherd, especially if there be a wood 

 near enough to offer him a hope of shelter. He will resist 

 the most tempting morsel when accompanied by this alarming 

 accessory [the smell of man] ; and even when it is divested of 

 it, he is long in overcoming his suspicions. In this case the 

 wolf can only have an abstract idea of danger — the precise 

 nature of the trap laid for him being unknown. . . . Several 

 nights are hardly sufficient to give him confidence. Though 

 the cause of his suspicions may no longer exist, it is reproduced 

 by memory, and the suspicion is unremovcd. The idea of 

 man is connected with that of an unknown danger, and makes 

 him distrustful of the fairest appearances." f 



Leroy also well observes: — "Animals, like ourselves, are 



* In my previous works I have already quoted facts of animal intelligence 

 narrated by this author, but not any of those which I am now about to use. 

 t IiitcUigcnce of Atiiiiuils, English trans., p. 20. 



