Ixyi 
INTRODUCTION. 
by experiments equally as decisive, that they only fall into a state of torpi- 
dity when exposed to the power of a cold atmosphere. But the second 
hypothesis, to account for the disappearance of Swallows, and the places 
of their retreat, is marked by monstrous absurdity and preposterous belief ; 
physical impossibility, gross delusion, and eager credulity, here walk hand- 
in-hand. The advocates of submersion deny their annual flight to distant 
regions, and represent the poor delicate birds, that studiously shun at other 
times every appearance of humidity, as assembling to immerse themselves 
in rivers, lakes, and ponds. On their margins, at the approach of winter, 
they magically lose their usual antipathy, and become anxious to sink in 
the stream, on which before they never ventured to recline. A grand 
funereal dirge is performed, as the proemium to the tragedy, and they plunge 
into the watery element, while the song quivers in their throats. Without 
recurring to the assertions of mariners, many of whom have seen the 
Swallow in its migration ; without referring to the testimony of travellers, 
vrho have discovered it in Africa at the period of our European winters ; 
without adverting to the testimony of Herodotus, who avers, that the 
Swallow lives in Egypt throughout the year ; one argument alone will 
overthrow the supposition, that it is capable of sustaining life for months 
in a watery grave. The great anatomist, John Hunter, dissected numbers ; 
and, in the objects of his inspection, he found the organs of respiration 
similar to those in other land birds ; consequently, as an animal fitted only 
for terrestrial existence, it could not long survive in a subaqueous retreat. 
See Adanson’s Vo3'age to Senegal, Admiral Wager’s Letter to Mr. Collinson, and Mr. Pear- 
son’s Account, in the Philosophical Transactions, of Swallows remaining active throughout the win- 
ter. Barham, ill his Travels in North America, says, that he has seen vast flocks of Swallows and 
Sand-martins passing onward from Florida northward toward Pennsylvania to breed, about the 
middle of March. Frisch tied bits of water-coloured thread round the legs of Swallows before 
their departure, which returned in the spring, with the thread not discoloured. And Buffbn 
placed many in an ice-house, but the congelation soon destroyed them. And it should be 
remarked, that the tail of the young Swallow at its departure it but slightly forked, but on its 
return it cannot in this respect be distinguished from its parents. 
