COMPARATIVE ANATOMY. 
123 
large terrestrial animals a close resemblance. In all life is 
sustained, and the body nourished by nearly the same ap¬ 
paratus. The heart, the lungs, the stomach, the liver, the 
kidneys, are much alike in all. The same fluid (for no 
distinction of blood has been observed) circulates through 
their vessels, and nearly in the same order. The same 
cause, therefore, whatever that cause was, has been con¬ 
cerned in the origin, has governed the production of these 
different animal forms. 
When we pass on to smaller animals, or to the inhabi¬ 
tants of a different element, the resemblance becomes more 
distant and more obscure; but still the plan accompanies 
us. 
And, what we can never enough commend, and which it 
is our business at present to exemplify, the plan is attend¬ 
ed, through all its varieties and deflections, by subservien¬ 
cies to special occasions and utilities. 
I. The covering of different animals (though whether I 
am correct in classing this under their anatomy I do not 
know) is the first thing which presents itself to our observa¬ 
tion; and is, in truth, both for its variety, and its suitable¬ 
ness to their several natures, as much to be admired as any 
part of their structure. We have bristles, hair, wool, furs, 
feathers, quills, prickles, scales; yet in this diversity both 
of material and form, we cannot change one animal’s coat 
for another, without evidently changing it for the worse; 
taking care however to remark, that these coverings are, in 
many cases, armor as well as clothing; intended for pro¬ 
tection as well as warmth. 
The human animal is the only one which is naked, and the 
only one which can clothe itself. This is one of the proper¬ 
ties which renders him an animal of all climates, and of 
all seasons. He can adapt the warmth or lightness of his 
covering to the temperature of his habitation. Had he 
been born with a fleece upon his back, although he might 
have been comforted by its warmth in high latitudes, it 
would have oppressed him by its weight and heat, as the 
species spread towards the equator. 
What art, however, does for men, nature has, in many 
instances, done for those animals which are incapable of 
art. Their clothing, of its own accord, changes with 
their necessities. This is particularly the case with that 
large tribe qf quadrupeds which are covered with furs. 
Every dealer in hare-skins and rabbit-skins, knows how 
much the fur is thickened by the approach of winter. It 
seems to be a part of the same constitution and the same 
