icant advice of Cuvier's, to combine zooelogical and
anatomical studies in order to arrive at a clearer perception of the true
affinities among animals. To sum it up in one word, he tells us that the
secret of his method is "comparison,"--ever comparing and comparing
throughout the enormous range of his knowledge of the organization of
animals, and founding upon the differences as well as the similarities
those broad generalizations under which he has included all animal
structures. And this method, so prolific in his hands, has also a lesson
for us all. In this country there is a growing interest in the study of
Nature; but while there exist hundreds of elementary works illustrating
the native animals of Europe, there are few such books here to satisfy the
demand for information respecting the animals of our land and water. We
are thus forced to turn more and more to our own investigations and less
to authority; and the true method of obtaining independent knowledge is
this very method of Cuvier's,--comparison.

Let us make the most common application of it to natural objects. Suppose
we see together a Dog, a Cat, a Bear, a Horse, a Cow, and a Deer. The
first feature that strikes us as common to any two of them is the horn in
the Cow and Deer. But how shall we associate either of the others with
these? We examine the teeth, and find those of the Dog, the Cat, and the
Bear sharp and cutting, while those of the Cow, the Deer, and the Horse
have flat surfaces, adapted to grinding and chewing, rather than cutting
and tearing. We compare these features of their structure with the habits
of these animals, and find that the first are carnivorous, that they seize
and tear their prey, while the others are herbivorous or grazing animals,
living only on vegetable substances, which they chew and grind. We compare
farther the Horse and Cow, and find that the Horse has front teeth both in
the upper and lower jaw, while the Cow has them only in the lower; and
going still farther and comparing the internal with the external features,
we find this arrangement of the teeth in direct relation to the different
structure of the stomach in the two animals,--the Cow having a stomach
with four pouches, adapted to a mode of digestion by which the food is
prepared for the second mastication, while the Horse has a simple stomach.
Comparing the Cow and the Deer, we find that the digestive apparatus is
the same in both; but though they both have hor