PROGRESS OF MICROSCOPICAL SCIENCE. 
213 
In the dissection of insects, different methods of treatment and 
manipulation must be adopted, according as it is desired to learn the 
structure of any particular organ, or to prepare and mount specimens, 
and economize so as to get the greatest number of preparations from 
a single insect. In learning the anatomy of any insect, not previously 
studied, a few specimens must be sacrificed by cutting and picking to 
pieces. Bat material may be saved by following some methodical 
plan. External parts can of course be studied as they present them- 
selves, but it is worth while to preserve the dermo-skeleton, either 
whole, or in parts (sections), and this is best accomplished by boiling 
in solution of potash, then washing in cold water and removing with 
scalpel or brush any remaining soft parts (ligaments, membranes, 
tracheae, &c.). To mount them, a suitable fluid, spirit, turpentine, 
balsam, glycerine, &c., must be used, and a convenient size and 
shape of cell chosen. The parts composing the mouth require 
special attention, and should b3 S3parately mounted. The whole 
head may be divided in various directions, yielding longitudinal, 
transverse, and horizontal sections, each displaying some particular 
aspect. For example, a longitudinal section shows external and 
internal lateral views of the cranium with eye, antennal first joint 
(the antenna being cut off), mandible, maxilla, and palpi. Cross 
sections yield anterior and posterior views of the internal processes, 
separating the cranial and facial halves. Horizontal sections show 
external and internal aspects of the vertex of the cranium with orbital 
and antennal sockets, labrum, &c., or of base of cranium with maxilla 
and palpi, gula, labrum, lingula, paraglosssD, &c. The study of such 
sections of the dermo-skeleton, from which the soft parts are removed 
by boiling in solution of potash, is a necessary preliminary to the 
study of the very intricate anatomy of the soft parts contained within 
them — e. g., tongue, pharynx, oesophagus with its salivary glands and 
muscles, supra and infra-oesophageal ganglia and nerves, together 
with a mass of intracranial muscles arising from the inner surface of 
the cranium and internal processes, and attached to oesophagus, palate, 
and mandibles. 
The student will be greatly assisted, and valuable time saved, by 
purchasing all good insect preparations which he can obtain commer- 
cially. Such preparations will probably be far better made and 
mounted than those which he makes for himself. But no cabinet of 
preparations will teach that knowledge of insect anatomy which is to 
be gained only from actual dissection. The relation of the soft parts 
to the dermo-skeleton, and their own relative position to each other, 
can only be learnt in their entirety by those who dissect them in the 
fresh state and examine them in situ. Besides which, preparations of 
the most important and interesting parts are not usually made for 
sale, as they are difficult to dissect, and demand much time in 
preparing. But whilst dissecting for himself, the student will find 
every tissue and fragment of tissue well worthy of study from 
histologic points of view, as well as on account of their anatomical 
relations. For instance, it is always well to examine fragments of 
muscle fibre scattered in the field, for the chance of securing good 
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