OF MICROSCOPIC OBJECTS. 15 
bone, &c., and rendering them plastic. Very thin laminz of 
these substances may also be procured by the employment 
of a well-sharpened scraper, such as that used by cabinet- 
makers. This plan applies more to longitudinal than to 
transverse sections; yet even the latter may be obtained by 
fixing the object while soft in a piece of hard wood, and 
scraping both together. Long continued slow boiling softens 
and eventually disintegrates nearly all animal and vegetable 
tissues. Muscular fibre and many other textures may thus 
be isolated, such as spiral vessels, &c., in vegetables. 
Prolonged maceration in water, for the preparation of 
anatomical structures, generally bony, is a process too well 
known to need description here. The addition of very 
dilute nitric, hydrochloric, and acetic acids is much em- 
ployed for the separation of muscular fibres, both striated 
and smooth. ‘Two or three days are required, or even more. 
Nails may be softened very quickly by hot concentrated 
sulphuric acid—or, still better, by liquor potassz, strength 
about 25 to 27 per cent.—so as to show isolated and dis- 
tended cells by solution of the intercellular substance. 
Bones are softened, %.e. decalcified, by boiling or, still 
better, by slow maceration in weak solutions of nitric and 
hydrochloric acids, by the action of which the phosphate 
and carbonate of lime may be entirely removed. This pro- 
cess isolates the animal matter, 7.e. the osseine—sometimes 
miscalled gelatine—with all its peculiar fibres and processes. 
But bones may be treated in another way, so as to show or 
isolate the bone corpuscles with their processes, by removal 
or destruction of the intercellular substance. Though this 
can scarcely be called softening them, yet it may be most 
fitly mentioned here. For this purpose, a Papin’s digester 
is necessary. When the boiling of bones has been for a long 
time carried on by means of one of these machines, they 
seem to be dissolved; but on examination a coarse powder, 
consisting of the isolated corpuscles and their processes, is 
found at the bottom of the vessel, which will amply repay 
the trouble of examination. 
