306 PRACTICAL AND SCIENTIFIC ZOOLOGY. 
mulgated, will never compensate for the want of this 
primary requisite. In ordinary life, we see some people 
who have an instinctive perception of differences to a 
much greater degree than others: as if, in short, the 
faculty was natural to them. Such persons will always 
make the best naturalists. This keenness of perception 
can, doubtless, be acquired ; and, as no science requires 
more observation, or greater nicety of discrimination, 
than natural history, so, upon this account only, it is 
the very best pursuit that can engage the youthful 
mind; since it will be thus qualified to apply that 
acuteness and judgment upon greater things, in after- 
life, which may call for the ee of sound reason and 
just discrimination. Many people, for instance, would 
be utterly at a loss to discover the difference of structure 
between a swift and a swallow, even if the two birds 
were before their eyes. Their colours, it is true, are 
not the same; but both have little, triangular, short 
bills, long pointed wings, and fly and feed in the same 
manner. A glance, however, at their feet shows a ma- 
terial difference. This difference is so great, that a 
young naturalist would immediately be convinced they 
could not belong to the same genus; because these op- 
posite structures of the feet indicated a corresponding 
dissimilarity of manners. Again, we hear the names 
of butterfly or moth used indiscriminately, even by well- 
informed people; who, were they asked why, could 
give no satisfactory answer. A boy, who merely knew 
the first elements of entomology, might immediately 
answer by pointing to the antenne, or horns (as they 
are vulgarly called), of the insect, and stating, that in a 
butterfly these members end in a thickened knob; 
while in the generality of moths they terminate in a fine 
point. This tact for observation, like every other habit, 
is to be acquired by practice; and the more it is exer- 
cised, the more acute it becomes. The student would 
derive much advantage, in this respect, from placing 
before him ten or a dozen species of insects very closely 
resembling each other: such, for instance, as those com- 
