SWALLOW TRIBE. 4? 



These examples, to whicli many more might 

 easily be added, will be sufficient, I am per- 

 suaded, to convince every unprejudiced mind, 

 that the parental affections of the feathered 

 tribes in general, and, what is more immediately 

 to the purpose, of the swallow and house-martin 

 in particular, are powerfully excited during the 

 breeding season. Now, what, we may ask, can 

 induce the two last-named species, and the sand- 

 martin, deliberately to consign their offspring to 

 a painful and lingering death, in direct oppo- 

 sition to such intense feelings as these? The 

 cause assigned by Dr. Jenner, for conduct so 

 anomalous, is the desire to migrate; and this 

 desire, he maintains, is produced by a change 

 in the reproductive system, which, in the case of 

 the birds under consideration, is supposed to 

 take place prematurely. I say is supposed to 

 take place, for I do not see, how it is possible to 

 ascertain what individuals will desert their pro- 

 geny, before they carry their intention into effect; 

 and after the accomplishment of the act, no 

 opportunity of examining the internal state of 

 their organization can present itself; this notion, 

 therefore, it is pretty obvious, must have origi- 

 nated in conjecture. That the sudden departure 

 of the swallow, house-martin, and sand-martin, 

 under circumstances so peculiar as those we have 

 been contemplating, is occasioned by the desire 



