NATURAL HISTORY OF SELBORNE. 123 



throws upon insensible perspiration. The case is just the 

 same with blackbirds, etc. ; and farmers and warreners 

 observe, the first, that their hogs fat more kindly at such 

 times, and the latter that their rabbits are never in such 

 good case as in a gentle frost. But when frosts are severe, 

 and of long continuance, the case is soon altered ; for then 

 a want of food soon overbalances the repletion occasioned 

 by a checked perspiration. I have observed, moreover, that 

 some human constitutions are more inclined to plumpness 

 in winter than in summer. 



When birds come to suffer by severe frost, I find that the 

 first that fail and die are the redwing-fieldfares, and then 

 the song-thrushes. 



You wonder, with good reason, that the hedge-sparrows, 

 etc., can be induced at all to sit on the egg of the cuckoo 

 without being scandalised at the vast disproportionate 

 size of the supposititious egg ; but the brute creation, I 

 suppose, have very little idea of size, colour, or number. 

 For the commoti hen, I know, when the fury of incubation 

 is on her, will sit on a single shapeless stone instead of a 

 nest full of eggs that have been withdrawn : and, moreover, 

 a hen-turkey, in the same circumstances, would sit on in 

 the empty nest till she perished with hunger. 



I think the matter might easily be determined whether a 

 cuckoo lays one or two eggs, or more, in a season, by 

 opening a female during the laying-time. If more than one 

 was come down out of the ovary and advanced to a good 

 size, doubtless then she would that spring lay more than 

 one. 



I will endeavour to get a hen, and to examine. 



Your supposition that there may be some natural obstruc- 

 tion in singing birds while they are mute, and that when 

 this is removed the song recommences, is new and bold : I 



