1876. J 
(137) 
PROGRESS IN SCIENCE. 
Microscopy. — M. Ranvier communicates the following mode of preparing 
sections of bone to the “ Archives de Physiologie ” : — A portion of the shaft of a 
long bone is procured, and immediately on its removal from the body is 
plunged into water, and allowed to macerate for the space of a year, the 
water being frequently changed. At the end of that time the bone will be 
found to have become as white as ivory, and quite free from any adhering 
tissue. The objedl of immediately plunging the bone in water is to prevent 
the infiltration of the canals and substance of the bone with fat. Sections are 
to be made with a saw, and these sedtions are ground down on pumice-stone, 
and finally polished on a harder material. In order to remove the powdered 
fragments of bone which have been ground off, and fill the canaliculi and 
lacunas on the surface, it is sufficient to scrape the sedtion with a scalpel. It 
is then placed in a warm solution of aniline dye, and allowed to remain there 
for two hours, and afterwards dried on a water-bath. The sedtion is next 
rubbed on a hone, moistened with a 2 per cent solution of common salt. It 
is then washed in this solution, and permanently mounted in a mixture of 
equal parts of the solution of salt and glycerine. 
Great attention has been paid of late to the staining of tissues with aniline 
and other dyes. Many strudlural details are no doubt rendered more distindt; 
but of course here, as in every kind of microscopical observation, care must 
be taken to avoid errors of interpretation. 
It would appear, from enquiries in various journals, that many microscopists 
experience a difficulty in securing the cells of preparations mounted in 
glycerine. At the risk of repetition an effectual mode of preventing leakage 
is given, although, from the long time it has been in use, it might have been 
supposed that everyone had been acquainted with it. The objedt having been 
placed in the cell, and the cover adjusted, proceed to remove as much of the 
surplus glycerine as possible : if the quantity is large, as is sometimes the 
case with over-filled cells, most of it can be taken up by sudtion with a sharply- 
pointed pipette ; the residue should be carefully absorbed with fragments of 
blotting-paper applied with the forceps ; then, with a camel-hair brush and 
water, the cell and surface of the cover should be gently cleaned : care must 
be taken not to disturb the cover-glass. The varnish employed is the solution 
of shellac in wood-naphtha, known at the shops as “ Liquid glue ” or “ Patent 
knotting varnish,” and effedtually resists the adtion of the almost universal 
solvent glycerine, if properly applied. The cell having been cleansed as much 
as possible from surplus glycerine, apply the varnish with a small camel-hair 
pencil, by hand, running it into the angular cavity at the jundtion of the cell 
and cover-glass, taking care, however, that only the smallest possible portion 
of cell and cover is included in this first coat. When dry, carefully wash the 
slide under a gentle stream of water; a tap partially turned on, or the ordinary 
wash-bottle, will answer the purpose. The objedt of this washing is to 
thoroughly cleanse the cell from adhering glycerine, which could not be 
removed while the cover was loose : dry the slide carefully by wiping with a 
cloth, taking care not to touch the cell and cover, which require a very tender 
drying with blotting-paper gently applied : the next coat of varnish is now to 
be laid on, and the turn-table can now be used to advantage, as the cover- 
glass is not likely to be disturbed. Do not at present coat the whole surface 
of the cell, but leave some part bare for the next varnishing. When dry, wash 
again as before, as the success of the whole process depends upon the freedom 
of the surfaces from any trace of glycerine. After this apply several coats of 
the varnish, taking care to keep each coat very thin. Never attempt to varnish 
thickly, as the interior seldom or never hardens. When sufficient varnish has 
accumulated, as shellac varnish becomes brittle after a time, add, for security, 
three or four coats of gold-size : this is the most tenacious and reliable varnish 
VOL. VI. (N.S.) T 
