ENTOMOLOGY. 
151 
and inexpensive. The student of marine zoology may be left 
out of the question, because a seaside residence is more or less 
essential for his pursuits; but even he cannot do very much 
practically without dredging, which is a troublesome and expen- 
sive operation. On the other hand, the ornithologist must either 
buy his specimens, or drag his gun about with him wherever 
he goes, on the chance of falling in with some desirable species ; 
the representatives of other classes of animals than birds and 
insects in inland situations in this country are too few to enable 
them to come into competition with the latter. The ento- 
mologist requires only a net or two and a few pillboxes and 
bottles, all of which he can carry in his pockets, to set him up 
in his pursuit ; and when he brings home his prizes he wants 
only two or three papers of pins, a few pieces of cork, and a 
close-fitting box or two lined with cork, for the preparation and 
preservation of his specimens. No doubt, with his progress, the 
appliances made use of by the entomologist will increase in 
number and complexity; but the student of most other branches 
of zoology must either skin and stuff his specimens or preserve 
them in spirit or some other fluid, and his collections will in 
consequence cost more and occupy much more space. 
As the characters upon which insects are classified are nearly 
all external — that is to say, derived from parts which may be 
investigated without destroying the specimens — their systematic 
study is very easily pursued, whilst their small size, by enabling 
a large number of species to be brought together within a very 
limited space, affords peculiar facilities for the comparison of 
characters, and for the recognition of the agreements and differ- 
ences presented by the members of the same group. If the 
entomologist chooses to go further, and to investigate the 
anatomical structure of the objects of his study, their smallness 
may at first sight seem to be an obstacle in his way, but this is 
soon got over, and it then becomes an advantage, seeing that, 
owing to it, such researches may be carried on anywhere, without 
the necessity of devoting a special apartment to the purpose, 
which can hardly be dispensed with in the case of vertebrate 
animals. Moreover, as the hard parts of insects are nearly all 
outside, their anatomy, which is perhaps the most interesting of 
all, may be studied with the greatest ease, and in fact the most 
instructive parts of the morphology of insects are those which it 
is essential for the student to know in order to understand their 
classification. Thus, for example, the investigation of the structure 
of the mouth in insects of different orders will give the student 
a clearer idea of the meaning of the term homology , and of the 
changes which the same parts may undergo in animals, than 
could be furnished him by any other examples ; and the series of 
modifications, occurring not only in the various types, but even 
