16 NATURAL HISTORY OF SELBORNE 



to arise altogether from the gentle check which the cold 

 throws upon insensible perspiration. The case is just the 

 same with blackbirds, &c. ; and farmers and warreners ob- 

 serve, 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 surfer by severe frost, I find that 

 the first that fail and die are the redwing-fieldfares, 1 and 

 then the song-thrushes. 



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

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

 without being scandalized 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 common 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 nest full of eggs that have been withdrawn : and, moreover, 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. 2 



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



Your supposition that there may be some natural 

 obstruction in singing birds while they are mute, and that 



1 So printed in the original edition. The paragraph should doubtless read 

 "redwings, fieldfares." See note to Letter IX. [R. B. S.] 



2 Dr. Rey, who has given particular attention to the life-history of the Cuckoo, 

 believes that each female lays about twenty eggs in the course of a season, and 

 these are laid on alternate days. Each female Cuckoo lays similar eggs through- 

 out its life. See my ' Wonders of the Bird- World,' p. 316. [R. B. S.] 



