246 THE BOOK OF MIGRATORY BIRDS 



Observers, past and present, are divided in opinion on 

 this very interesting subject. The regular appearance and 

 disappearance of some species of birds excited the curiosity 

 of observers in all ages, and led to many conjectures 

 respecting its causes. 



It was long alleged and believed that swallows, instead 

 of removing to warmer climates, lie concealed in fissures 

 of rocks, in sand-banks, in the holes of decayed trees, and 

 even at the bottom of the water in ponds, remaining 

 during the winter in a torpid state. 



"It is certain," said the Dutch naturalist Jonston, "that 

 in hollow trees, lying many close together, they preserve 

 themselves by mutual heat." 



"In certain woods of Upper Germany," said another 

 authority, "upon cutting up a rotten oak tree it was found 

 full of swallows." 



Unfortunately for the credibility of such accounts, 

 however, they all wear the aspect of fanciful conjecture, 

 rather than of a fact actually observed ; and though there 

 are accounts of similar circumstances purporting to be from 

 actual observation, they all appear suspicious when strictly 

 investigated. 



In our own. county of Northumberland it has been 

 jeported more than once, notably on the authority of the 

 late Lord Belhaven, "that numbers of swallows have been 

 found in old dry walls and in sandhills at Morpeth, and 

 also near his late lordship's seat in East Lothian ; not once 

 only, but from year to year, and that when they were 

 exposed to the warmth of a fire they revived." 

 , Etmuller, Professor of Botany and Anatomy at 

 Leipsic, gives his testimony thus: "I remember," he 

 said, r 'to have found more than a bushel measure would 

 Jiold of swallows closely clustered among the reeds of a 

 fish pond under the ice, all of them in appearance dead, 

 but the heart still pulsating." Against this I place the 

 experience of no less an authority than the late John 

 Hunter. 



"I have dissected many swallows, but found nothing in 



