84 CLASS AVES. 



tion of Swallows, has probably originated the absurd systems 

 incompatible with all the principles of physiology, which have 

 been invented to account for the periodical disappearance of 

 these birds, although the actual fact of emigration is more 

 easily observable in them than in any other of the class. 



A bishop of Upsal in 1555, Olaus Magnus (the epithet 

 could not have been applied to him as a naturalist), asserted 

 that the fishermen in northern countries frequently caught in 

 their nets clusters of swallows attached closely to each other, 

 which, if kept sufficiently warm, were soon restored to ani- 

 mation, and that those left in the water, on the approach of 

 warm weather, rose to the surface, and then took to flight, 

 resuming their accustomed habits. However incredible this 

 tale, it was generally received, and even supported by real 

 observers of nature, among whom must be reckoned even 

 the great Linnaeus ; a position, however, emanating from such 

 a source, and recommended by such authority, was certainly, 

 in respect not to itself but its supporters, deserving serious 

 investigation, which it has therefore meritedly undergone. 



Montbeillard, who has examined tbis story, observes, that if 

 it were true that all the swallows of any particular place or 

 country, voluntarily plunged into the water yearly in October, 

 and quitted it again in April, there must have been frequent 

 opportunities of verifying the fact, either at the period of 

 their immersion, or their subsequent emersion : yet no credible 

 witness, whose veracity and judgment could be relied on, has 

 vouched for having seen it ; and notwithstanding the re- 

 wards offered at different times, no specimens of swallows 

 found in a state of suspended animation under water, have 

 ever been forthcoming. The certificates produced by Klein, 

 (another supporter of this doctrine) in his dissertation De 

 Hyhernaculis Hirundinum^ speak only of isolated facts, not 

 recent, or else founded on mere hearsay. Testimonies of this 

 sort cannot avail against the established physiological princi- 



