48 HISTORY OF T^E 



to migrate, I do not dispute; but that this desire 

 results from certain changes which occur periodi- 

 cally in the condition of the reproductive system, 

 seems quite inadmissible. Indeed, the undenia- 

 ble facts, that every species of the feathered 

 tribes, though subject to these changes, is not 

 migratory; and that snipes, wild-ducks, &c., 

 breed annually, and woodcocks occasionally, in 

 countries where the majority of these birds is 

 known to sojourn during the winter only, are so 

 totally subversive of Dr. Jenner's hypothesis, 

 that to attempt a more complete refutation of it, 

 in this place, would be superfluous. 



It is particularly deserving of remark, that 

 the early death, which invariably terminates the 

 sufferings of those devoted nestlings that are 

 abandoned by their parents, powerfully militates 

 against an opinion, extremely prevalent amongst 

 ornithologists of the present day, that many of 

 our summer birds of passage, especially the 

 swallows, are capable of passing the winter sea- 

 son in a state of torpidity ; for, if this belief in 

 the liability of the European hirundines to be- 

 come torpid in autumn be well founded, how 

 does it happen, that late hatched broods of swal- 

 lows, house-martins, and sand-martins, when 

 deserted, uniformly perish, even under circum- 

 stances which are represented as rendering indi- 



