ANATOMY AND PHYSIOLOGY. 83 
quite intelligible and fixed in the memory with a 
very little pains. Wasps and microscopes are so 
very common, and so easily accessible, that I have 
introduced the diagram on a preceding page rather 
to pomt out which are the parts to the student than 
to attempt to show what he might so readily see for 
himself in the book of Nature. On the other hand, I 
must add, with as little doubt, I am sorry to think, 
that this description, after all my endeavours to 
simplify and shorten it, will have appeared dry and 
tedious. I must acknowledge that all these details 
are somewhat repulsive; but, if they are to be 
mastered at all, they require close attention. And 
the labour will be amply repaid; for on the form 
of the parts of the mouth which have just been 
reviewed, and especially on the numbers of the 
sub-divisions, wherever this mode of comparison is 
applicable, specific distinctions are based which are 
not the less valuable because they require a micro- 
scope to display them. 
It certainly gives a higher interest to such details, 
and assists both to understand and retain them in 
the memory, to :transfer to the parts of insects the 
terms of the anatomy of the higher animals. But it 
is only with great reservation that we can venture 
thus to apply these terms. Many entomologists, as 
has already*been said, doubt whether the horny 
covering of insects be not more strictly analogous to 
our outer skin than to our internal skeleton. And 
we should bear the possibility of the reasonable 
existence of a doubt on such a fundamental pomt in 
mind when we go beyond this and attempt to trace 
any close analogy in detail between the parts of the 
G2 
