252 FACULTIES OF BIRDS. 
geese or any other bird that I have seen; and, there- 
fore, quaffer and grope out their meat the most. But 
then I discovered none of these nerves in round- 
billed: birds. But since, in my anatomies in the 
country, in a rook, I first observed two nerves that 
came down between the eyes into the upper bill, but 
considerably smaller than any of the three pair of 
nerves in the bills of ducks, but larger than the 
nerves of any other round-billed birds. And it is 
remarkable that those birds, more than any other 
round-billed birds, seem to grope for their meat in 
cowdung.”* 
The facts thus proved by the structure of the or- 
gan are corroborated by the actions of the birds 
themselves. There can be little doubt indeed that 
animals may sometimes be deceived into eating what 
is unwholesome, or even poisonous. But this, it is 
probable, happens much more rarely in those en- 
dowed with acute smell than in others; for, accord- 
ing to the beautiful remark of Cicero, borrowed, it 
is highly probable, from the Greek philosophers, 
‘‘ the nostrils are providentially placed high, because 
odours have a tendency to rise, and are also near 
the mouth for the purpose of descriminating food 
and drink.” Even very young ducks, accordingly, 
will reject from the mud in which they may be fish- 
ing such substances as they judge by smell to be 
unfit for food, while they will eagerly swallow a bit 
of biscuit which, for the sake of experiment, may 
be concealed among the mud; and they will as ea- 
gerly seize and swallow any animal garbage which 
they find in the same place, and which has just been 
rejected by their fellow-swimmers the swans, whose 
food is wholly vegetable.t Dr. Darwin was there- 
fore in some degree right in the following remarks, 
though he evidently carries his principle to ex- 
tremes which facts will not altogether justify. 
* Phil. Trans., No. 206. + J. Rennie. 
