148 COMPARATIVE ANATOMY AND PATHOLOGY. 
These are herbivorous animals, and their adaptation to their 
situation and food is beautifully developed ; but their nutriment is 
usually within reach, and all that is necessary for them is to be 
enabled to distinguish the wholesome from the poisonous, and the 
healthy from the decayed and injurious. 
Carnivorous Animals . — Let us look to the carnivorous quadru- 
peds. How indistinct must be that scent which is communicated 
to and lingers on the ground by the momentary contact of the foot 
of the hare, the fox, or the deer ; yet the hound recognizes it for 
many an hour — some sportsmen say for more than twenty-four 
hours. He can not only distinguish the scent of one species, of ani- 
mal from another, but that of different animals of the same species. 
The bloodhound will follow the track of the man whom he pursues, 
although hundreds of other men may have crossed his path. The 
fox-hound, well broken-in, will rarely challenge the track of any 
other animal, nor will he be imposed upon, when the prey which 
he pursues has taken refuge in the earth, and thrust out a new victim 
before the pack. 
Varieties of Carnivora . — We have still more palpable and inte- 
resting illustrations of our subject in the different breeds of dogs. 
Compare the size of the olfactory nerve in the beagle and in the 
bull-dog ; the one valued for the delicacy of his scent, the other 
used only for horrible and disgraceful purposes. It is considerably 
more developed in the diminutive beagle than in the other brute of 
superior size. I take a still more striking illustration ; I examine 
the greyhound, w'ho hunts by sight alone, and the stag-hound, who 
hunts by scent. There is not a great deal of difference in their weight, 
but there is a considerable one in the bulk of brain, — the one a highly 
intellectual animal — the other requiring not any peculiar degree of 
sagacity. There is a still more striking difference in the bulk of the 
olfactory nerve : in the one connected only, and that not to any 
great degree, with the welfare of the animal ; the other identified 
with the service which he can render to man. 
In the Bird . — In the feathered biped there is the same propor- 
tion between the bulk of the olfactory nerve and the quickiiess of 
scent. There has been much dispute on this point among orni- 
thologists. Some have denied the quickness of scent which has 
been usually attributed to the bird. Audubon — a name that stands 
deservedly high as a naturalist — says that vultures and other birds 
of prey possess the sense of smell in a very inferior degree to car- 
nivorous quadrupeds, and that, so far from guiding them to their 
prey from a distance, it affords them little indication of its presence 
even when close at hand. In t confirmation of this opinion, he 
states, that he stuffed the skin of a deer full of hay, and placed it 
in a field, and in a few minutes a vulture alighted near k, and 
