NATURAL HISTORY OP SELBORNE. 
99 
reed-sparrow of the Zoology, p. 320 ; or was it the less reed-sparrow of \ 
Kay, the sedge-bird of Mr. Pennant's last publication, p. 16 \ 
As to the matter of long-billed birds growing fatter in moderate 
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 blackbirds, &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 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, &c., 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 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have been withdrawn: and, moreover, a hen-turkey, in the same 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. J 
I will endeavour to get a hen, and to examine. 
Your suppositioin that there may be some natural obstruction in 
singing birds while they are mute, and that when this is removed the 
song recommences, is new and bold : I wish you could discover some 
good grounds for this suspicion. 
I was glad you were pleased with my specimen of the caprimulgus, 
or fern-owl ; you were, I find, acquainted with the bird before. 
* See Letter XXV. 
t By a wise provision, and to prevent the very circumstance which Mr. White 
here notices, we find the egg of the cuckoo scarcely larger than that of the common 
chaffinch. 
X The remarks of Mr. "White are made in consequence of Mr. Barrington's letters 
to him, the contents of which were embodied in an essay, published in his Mis- 
cellanies, in 17^, " On the prevailing notions in regard to the Cuckoo," in which 
he quotes a letter from Mr. White (Letter XXIV.). Barrington had imbibed some 
very erroneous notions himself, and combats the idea that the small birds, such 
as hedge-sparrows, &c., could hatch a cuckoo ; and also tries to produce evidence 
that the cuckoo is not a parasitic breeder. Professor Owen has remarked, ' ' I am 
not aware that more than one ovum is ever contained in the oviduct at one time, 
in any bird. " There is no reason for believing that the cuckoo does not, as other 
birds, deposit a certain number of eggs each season : so far as we know, there is 
nothing peculiar in its structure referrible to this, and its residence in the 
breeding localities is protracted much beyond the time required to deposit a 
smgle egg. 
H 2 
