OF MICROSCOPIC OBJECTS. 189 
are very beautiful transparent objects. Some of the finer 
tissues, also, are shown much better by this mode of in- 
jection than by the opaque, and are easily mounted by 
washing in clean water when first separated, and floating 
upon a slide, where they must be allowed to dry thoroughly. 
They may then be immediately mounted in balsam, or kept 
in the dry state until it is convenient to finish them; but 
in many cases this keeping, if too much prolonged, will 
injure the object. If it is desired to transfer the section to 
another slide, it will be necessary to wet it thoroughly with 
water by the aid of a camel-hair pencil, and then gently 
strip it off with the forceps. When it is wished to preserve 
injected subjects in masses, it must be done by immersion 
in spirit, and the sections may be cut at leisure. Most of 
these: transparent objects may be mounted in Canada 
balsam; but some recommend glycerine or glycerine jelly, 
as allowing the use of a higher power in their examination, 
and preserving them in a more natural form. 
34. A few subjects may be noticed which are very beauti- 
ful when injected, and amongst these are the eyes of many 
animals. They must be injected by the artery in the back 
part, and when the blue transparent liquid is employed, 
nothing can exceed the delicate beauty displayed by some 
of the membrane. It must be dissected with care, but well 
repays us for the trouble. Water-newts and frogs are not 
difficult subjects, and in their skin and other parts are many 
interesting objects. Amongst the commoner animals—rats, 
rabbits, cats, &c.—almost endless employment may be 
found, making use either of portions or the whole animal at 
once. The intestines of many of these are very beautiful. 
We must divide them with a pair of scissors along the tube, 
and cleanse them from the contents; the specimen may 
then be laid upon a slide, and any remaining impurity 
removed by a camel-hair pencil and water. When dried it 
may be mounted in balsam, and having been injected with 
the transparent blue, its minute beauty is shown most per- 
fectly. In injecting a sheep’s foot, which is a good object, 
