OF SELBOKMv 125 



Was your reed-sparroWj which you kept in a cage, the 

 thick-billed reed-sparrow of the Zoology, p. 320 ; or was it 

 the less reed-sparrow of Ray, the sedge-bird of Mr. Pennant's 

 last publication, p. 16 ? 



As to the matter of long-billed birds growing fatter in mo- 

 derate frosts, I have no doubt within myself what should be 

 the reason. The thriving at those times appears to me to arise 

 altogether from the gentle check which the cold throws upon 

 insensible perspiration. The case is just the same with black- 

 birds, &c. ; 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 sueh 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 ob- 

 served, moreover, that some human constitutions are more 

 inclined to plumpness in winter then 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, &c. 

 can be induced to sit at all on the egg of the cuckoo without 

 being scandalized at the vast disproportioned size of the sup- 

 posititious 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 been withdrawn : and, moreover, a hen-turkey, in the same 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 *. 



* [In Mr. Bennett's edition is a note by Professor Owen on this subject, 

 which leaves the question, to a certain extent, undetermined as regards its 

 anatomical phase ; for, although but one egg- was found in the oviduct, 



