VIEWS ON MIGRATION. 9 



that Swallows sink into lakes in autumn, and hiber- 

 nate in a manner precisely similar to frogs. In 

 1 741, Fermier-General Witkowski made legal testi- 

 mony to the effect that two Swallows had been 

 taken from a pond at Didlaeken in his presence, in 

 a torpid state ; that they eventually regained anima- 

 tion, and after fluttering about, died some three 

 hours after their capture. In 1748, the great 

 Swedish chemist Wallerius, wrote that he had on 

 several occasions seen Swallows clustering on a 

 reed, until they all disappeared beneath the surface. 

 In 1750, Kalm the traveller observed Swallows 

 on the loth of April, sitting on posts near the 

 sea, with their plumage wet as though they had 

 just emerged from the water. Four years later, 

 J. R. Forster (editor of K aim's Travels in North 

 America) was an eye-witness, so he informs us, 

 to the following. In January 1754, several Swallows 

 were taken from the lake of Lybshau, then covered 

 with ice, one of which he carried home, where it 

 regained its vitality, but died soon afterwards. In 

 1764, Achard, referring to Swallows on the Rhine, 

 states that they have been found apparently stiff 

 and lifeless in holes in sand-clifFs, ultimately be- 

 coming reanimated. This record doubtless refers 

 to the Sand Martin {Cotijle riparia), and is inter- 

 esting. Between the years 1767 and 1780, Gilbert 

 White's letters to Thomas Pennant and Daines 

 Barrington (the latter then a vice-president of the 

 Royal Society of England) contain many references 

 to the hibernation of birds, and clearly show that 



