SPARROWS, TROUT, AND BREEDING 269 



and lakes do or do not exhibit increased " wariness," or 

 even " intelligent caution " in avoiding the flies so cunningly 

 thrown before or above them by the skilful angler. It is 

 argued that there cannot really be any increased indisposi- 

 tion of trout to take the fly based on experience, because 

 on an estimate of the number of trout in a river like the 

 Test, and of the limited number of anglers, every fisher- 

 man would have to hook and lose some thousands of fish 

 every year for the experience to be general among trout 

 that the horrid artificial flies "hide a still more horrid 

 hook." It is, of course, held that the trout cannot com- 

 municate their experiences to one another by any form of 

 conversation (though leadership and imitative habit might 

 have some effect), and it is also not suggested that a trout 

 which had acquired an overpowering aversion to the 

 angler's fly as a result of being hooked and breaking free, 

 could transmit that aversion to its offspring by the mere 

 fact of reproduction. Hence it is maintained that there is 

 no such increasing " wariness " in English and Scotch 

 trout. It is a curious thing that in discussing this matter 

 the fundamental principle should have been overlooked by 

 which Darwin and Wallace have long ago explained to 

 the satisfaction of naturalists, the aversions and cautious 

 proceedings of all kinds of animals, from the smallest 

 insects up to birds, beasts, and fishes. The principle of 

 natural selection and survival of the fittest accounts for 

 the increased caution of trout in well-fished rivers in the 

 simplest way. Assume (as is perfectly reasonable) that 

 some trout are more shy than others " by nature," that is 

 to say, are born so, that some are born with a slightly 

 more rapid response to the sight of food than others as 

 one sees often enough with a lot of the young of any 

 animal then the increased shyness or pretended " intelli- 

 gence" of the trout after many years' fishing follows as a 

 necessity. The rash fish are caught and destroyed, the 



