ON THE MIGRATION OF BIRDS. 129 



confined migratory birds during the winter, we may safely believe that Mr. 

 Pearson's Swallows manifested, at the usual time, a strong migratory feeling. 

 This, probably, was either unnoticed, not understood, or thought unworthy of 

 record, by the experimentalist. The want of ability to gratify a desire does not 

 prove that such a desire is not felt. Yet on Dr. Bushnan's grounds we must 

 believe, that because the Swallows could not migrate, they had no inclination to 

 do so. He might as plausibly contend, that a man after a three- days' fast would 

 have no sensations of hunger, if he were unable to procure food. 



As the excitement of the organ of Locality occurs in birds kept in cages in 

 & warm temperature, and abundantly supplied with food, another class of 

 naturalists are of opinion that coldness and scarcity of provision have no influence 

 whatever in producing periodical migration. 



Both these extreme opinions appear to be erroneous. I am inclined to believe 

 that, at first, the coldness of climate, and want of nourishment, were the only 

 causes of migration, but that now, this habit, continued through so many genera- 

 tions, has such an influence over the species, that the involuntary excitement of 

 the organ, at stated periods, must exist, although the want of food, or change of 

 temperature, is not felt. I have no doubt, however, that these still continue to 

 add a great stimulus to the excitement.* Nor is this explanation improbable. 

 In fact, that peculiar habits, &c, of men are transmitted to their offspring, is so 

 well known, that it is unnecessary to enforce it here. The same influence is 

 found also in the animal kingdom. " Abilities," remarks Mr. Jesse, " which 

 have been kept up by practice throughout several generations, may finally be 

 propagated as natural propensities. I had a young Pointer which found, and 

 pointed at game, the first time he was taken into a field. The descendants of a 

 breed of Terriers, which I have had many years, shew their teeth, and put out 

 their paw when they are caressed. This is a peculiarity of the breed. Young 

 South Sea Islanders are said to be able to swim when first put into the water."t 



* We are disposed to take a different view of the case, believing, as we do, that all migratory 

 birds must ever have possessed the organ of Locality — and likewise every other faculty — in the 

 same degree that they now possess it ; and that, without the innate feeling which now induces 

 birds to travel, no individual species would ever have quitted its native country, to which it is 

 naturally wedded by other equally innate powers. This argument is supported by the fact that 

 the lower animals, like Man, so long as they remain in a wild and savage state, continue unaltered 

 in their habits. The feeling of hunger or of cold would only impel the animal to seek food, and 

 would not teach it that by crossing the seas sustenance might be procured. Thus although, by 

 adverse winds or other accidents, single individuals may occasionally be cast on strange shores (an 

 occurrence which has, of late years especially, considerably increased the British Fauna), the 

 laws which govern migration are found to be fixed. That birds were originally, and still are, im- 

 pelled to migrate by the innate faculty of Locality is, therefore, tolerably certain, though the 

 feeling which directs their course is not quite so obvious. — Ed. 



t Jesse's Gleanings in Natural History, 3d Series, p. 149. 



