him the general direction in which he is to travel. 

 This instinct is, no doubt, helped by the eyes, for in- 

 stance in choosing the narrowest passage when a 

 voyage over sea has to be made. Flying at a great 

 height a Swift will be able on a clear night to see the 

 striking features of the country from a long way off, 

 and this will help him to keep his course. But the 

 eye cannot do more than assist and correct the instinct. 

 The migrant's faculty differs from that of the Pigeon, 

 in that it directs him to a place with which, not he, 

 but his parents, are familiar. Marvellous as this no 

 doubt is, we must be very careful not to exaggerate 

 the miracle. The young Swallow has only to make 

 for the south, not to find any exact spot. When he 

 returns in spring, he often steers for the particular 

 barn or chimney where his earliest days were passed. 

 Moreover, though the young birds are the first to 

 start, it is believed that there is much loitering on 

 the autumn migration, and it is possible that they 

 may be overtaken by the old birds and attach them- 

 selves to them. Whatever may be the power by which 

 they guide themselves, in many of them it is im- 

 perfectly developed and fails them in their need. 

 On no other supposition can we account for the fact 

 that so small a percentage ever return. 



Though we decide that they find their way by in- 

 stinct, we have not advanced far towards the under- 

 standing of the problem. An instinct is an inborn 

 faculty, distinct from reason, though reason may act 

 upon it and modify it, and this particular instinct we 

 cannot understand, because we have something only 

 very remotely similar to it in ourselves. In attempt- 



