‘ - THe MICROSCOPE. 47 
posterior border of the pharynx appears to undulate with the long 
cilia about the peristome field. I incline strongly to the opinion that 
our form is the same species, except that it is not “cordiformis.” Is 
the European? 
CotumBus, Ouro. 
ELEMENTARY DEPART MEN: 
A COURSE IN ANIMAL HISTOLOGY. 
EIGHTH PAPER. 
FRANK W. BROWN, M. D. 
ONE.—Because of its extreme hardness, the preparation of 
microscopical specimens of bone requires much care and 
patience, and even then the results are often far from satisfactory. 
Indeed, until recently-suggested methods of infiltration were 
employed, no specimens were produced which could be said to give 
even approximately correct studies of this tissue. By the older 
methods, of which there are two, the soft parts of the bone were 
completely altered or entirely destroyed; yet, as they require less 
time in their performance and give a tolerable idea of the relations 
of the hard and soft parts, they are given here. 
(1.) With a fine saw make as thin sections as possible from a 
small, long bone; one of these is to be rubbed down with emery on astone 
until as thin as practicable and then polished on a hone or piece of 
ground-glass. Wash thoroughly in water to remove the debris, and 
mount dry or in Canada balsam. If mounted in balsam it should be 
well dried and not cleared in clove oil or turpentine. The dry 
method is to be preferred, as when mounted in some medium the 
specimens are apt in time to become too transparent. If the worker 
have sufficient patience, longitudinal sections should be made after the 
same manner. 
~ 
(2.) If the bone is decalcified, sections can be made from it — 
with a razor as from any other soft tissue of the body. To decalcitfy, 
saw off a section, one-quarter to one-half an inch thick, from a fresh, 
Tong bone. Place it for a few days in a one per cent. solution of 
chromic acid, and then transfer to a fluid composed as follows: 
Hydrochloric acithage:..2.40.0.5 Gags se 5) 
leghols mie. : .. higmy etal. as oy Trees 1,000 
Dis lled water :'s/paet dire ne ees 200 
Chloride of sodium..............-- 5) 
(Friedlander. ) 
