284 ANNUAL REPORT SMITHSONIAN INSTITUTION, 195 4 



by noting the position of the sun, even if there were no signposts and 

 no one to tell the way. But that would be because you carry a mem- 

 ory of the maps you have seen, and know that you are in England : 

 if you were similarly placed in France, but thought you were in Eng- 

 land, you would have considerable difficulty in finding your way until 

 your knowledge of geography and topography showed you that you 

 could not be in the country you thought. There seems to be no evidence 

 at all that we have any inherent sense of direction apart from immedi- 

 ate experience of our surroundings. If animals have any such sense 

 we do not share it. 



There has been some discussion about the possibility that birds may 

 be able to orientate themselves on migration in relation to the earth's 

 magnetic field, that they have some sense organ that is effectively a 

 compass. Some experiments were carried out with homing pigeons ; 

 small magnets were fixed to them to find out whether any effect could 

 be produced thereby upon their homing abilities. The results were 

 entirely negative, and moreover other experiments have shown that 

 birds appear to orientate themselves according to the true points of 

 the compass rather than the magnetic ones. It is improbable that 

 mammals differ in this point. 



We know, therefore, something of the facts about the migrations of 

 some mammals, but the means whereby migration is carried out still 

 remain completely unknown ; many theories have been tried but none 

 of them has been capable of experimental proof. It is all very puz- 

 zling; as far as we know the bodies of the other mammals are essen- 

 tially similar to our own, and we flatter ourselves that our brains are 

 more highly developed. And yet these animals that we classify as 

 lower than ourselves can do something, and presumably with their 

 brains too, that we cannot ; something so far outside our own experi- 

 ence and abilities that we cannot even conceive how they do it. Natural 

 selection has no doubt fixed the tendency to migrate in those species 

 where it is found, but that does not explain how it is accomplished. 

 There is obviously much more to be found out about the migration 

 of animals than we have yet discovered. 



REFERENCES 



Cbonwriqht-Schreineb, S. C. 



1925. The migratory springbucks of South Africa. Fisher Unwin Ltd., 

 London. 

 Duncan, Maetin F. 



1947. Wonders of migration. Samson Low. 

 Elton, C. 



1942. Voles, mice and lemmings. Clarendon Press, Oxford. 

 Heape, W. 



1931. Emigration, migration and nomadism. HefCer, Cambridge. 



