OF MICROSCOPIC OBJECTS. 163 
but perhaps the first-named may be preferred in many 
cases. 
Before treating of separate objects it will be well to notice 
what M. Brunetti has said on preparing anatomical speci- 
mens, The process consists of four stages—viz., washing, 
- divesting of fat, treating with tannin, and desicwation. A 
stream of pure water is injected through the blood-vessels 
and secretory ducts of the part to be preserved; the water 
is afterwards expelled by means of alcohol. ‘To remove the 
fat, the vessels are in like manner injected with ether, 
which penetrates the tissues and dissolves all the fatty 
matters. These operations occupy about two hours, and 
the object thus prepared may then be kept for a long time 
in ether, if desired. A solution of tannin is next injected 
in a similar manner, and the ether washed out by a stream 
of pure water. The preparation is then placed in a double- 
bottomed vessel containing boiling water—a sort of bain- 
marie—in order to displace the fluid previously used by 
dry heated air. Air compressed in a reservoir to about 
two atmospheres is forced into the vessels and ducts 
through heated tubes containing chloride of calcium: all 
moisture is thus expelled and the process is completed. 
The preparation thus treated is light, and retains 
its volume, its normal consistence, and all its histological 
elements. 
Musctz.—This is what is commonly called the flesh 
of animals. If a piece be laid upon the slide under the 
microscope, bundles of fibres will be perceived, which with 
needles and a little patience may be separated into portions, 
some of these being striated, or marked with alternate spaces 
of dark and light. Some of the non-striated or smooth class 
of muscle, such as is found in intestines, may be prepared 
for the microscope by immersing for a day or two in nitric 
acid diluted with three or four parts of water, and then 
separating with needles and mounting as soon as possible. 
Sometimes boiling is resorted to to facilitate the separa- 
tion, and occasions little or no alteration in the material. 
mM 2 
