ON THE SINGING OF BIRDS. 
which might be supposed to contribute to 
- singing. 
Mr. Hunter found the muscles of the larynx 
to be stronger in the nightingale than in any 
other bird of the same size; and in all. those 
instances (where he dissected both cock and 
hen) that the same muscles were stronger in 
the cock. 
I sent the cock and hen rook, in order to see 
whether there would be the same difference in 
the cock and hen of a species which did not 
sing at all. Mr. Hunter, however, told me, 
that he had not attended so much to their com- 
parative organs of voice, as in the other kinds ; 
but that, to the best of his recollection, there 
was no difference at all. 
Strength, however, in these muscles, seems 
‘not to be the only requisite; the birds must 
have also great plenty of food, which seems to 
be proved sufficiently by birds in a cage sing- 
ing the greatest part of the year,* when the 
wild ones do not (as I observed before) continue 
in song above ten weeks. 
* Fish also which are supplied with a constant succession of 
palatable food, continue in season throughout the greatest part 
of the year; trouts, therefore, when confined in a stew and fed 
with minnows, are almost at all seasons of a good flavour, and 
‘are red when dressed. 
343 
