J 4 THE MIGRATION OF BIRDS, 



observer who had furnished him with information 

 concerning the hibernation of birds therein described. 

 Both these latter incidents were dealt with in a 

 hostile spirit a few weeks later in Nature, by 

 Palmen's reviewer. In 1878, the hypothesis of 

 hibernation received by far the most powerful 

 support ever accorded to it in modern times, in 

 the writings of Doctor Coues, an American ornitho- 

 logist, and one of the most accomplished and 

 industrious naturalists this or any other century 

 has produced. In his first part of the Birds of the 

 Colorado Valley, he not only goes very fully into 

 the presumptive habit of hibernation, but he gives 

 the theory all the support of his authority as an 

 ornithologist of the highest eminence. He there 

 boldly states his belief (and I am not aware that he 

 has seen fit to change his opinion), that the 

 American Chimney Swift {Cluetiira pelagica) hiber- 

 nates in hollow trees, basing his opinion on the fact 

 that this species is not known to winter anywhere 

 out of the United States, nor is it found anywhere 

 in them at that season ; and of its swarming in 

 myriads in hollow trees, and sometimes perishing in 

 those places in such numbers that their remains 

 form solid masses several feet in thickness at the 

 bottom ! It is, however, only fair to say that Dr. 

 Coues, just like Gilbert White, is not by any means 

 a convert to the belief in universal torpidity, but 

 considers that in the majority of cases it is only 

 odd individuals that do so hibernate. As he 

 forcibly remarks, the migration of a million Swallows 



