1887.] MICROSCOPICAL JOURNAL. 31 
melted paraffine, kept at uniform temperature slightly above melting point, 
6-24 hours. The kind of paraffine, whether hard or soft, will depend upon the 
temperature of the room. If the room be cool, then the paraffine must be a 
soft one; if the section be cut in a warm room, or in summer weather, the 
paraffine should be hard. 
If the chicks be imbedded in this manner, which is certainly a tedious one, 
it will give the most perfect results. It is the manner in use in the great 
laboratories, and the way to imbedding for the wonderful ‘ ribbon method.’ 
We have never had any need of a flattener. The chick may now be removed 
from the melted paraffine and placed in the centre of a block, which is to be 
allowed to cool. When perfectly cold the block is placed in the microtome 
and the tissue will cut as easily as the paraffine. If the temperature conditions 
be regulated, and the room is neither too warm nor too cold, and the razor 
sharp, and cut with a straight, not a sliding, motion across the chick, slice 
after slice may be cut of even thickness and of the same area as the block of 
paraffine containing the specimen. These slices may easily be kept in their 
proper sequence and with the right side up, and cemented on the slide for 
clearing and the cover-glass: 
We have already written more on this subject than we at first contemplated, 
but said as little as possible to explain this method of section-cutting, which, 
after several years’ experience, we unhesitatingly adopt every day, in spite 
of its tediousness. 
A modification of Weigert’s method of staining tissues of the central 
nervous system. By Dr. N. M. Gray, Army Medical Museum, Wash- 
ington, D. C. 
The specimens hardened in Miiller’s or Erliki’s fluid are transferred directly 
(without coming in contact with water) to alcohol of 70 per cent. They are 
gradually dehydrated and finally soaked in absolute alcohol for several days. 
They are then soaked for one or two days in a mixture of equal parts of ether 
and absolute alcohol ; then transferred to a solution of celloidin and eventually 
imbedded in celloidin on cork. The pieces, still fastened to the cork in the 
celloidin, are immersed in a solution of neutral acetate of copper (a saturated 
filtered solution of this salt diluted with an equal volume of water) and allowed 
to remain in an incubator at 30° or 4o° C. for one or two days. 
The specimens become pea-green after the copper treatment ; the celloidin 
more of a blue-green. They may now be preserved in So per cent. alcohol 
indefinitely. 
After having made sections, which must still be kept clear of water, they 
are immersed in the hematoxylin solution, the formula for which is as fol- 
lows :—Hzmatoxylin (Merck’s in crystals), 1 part ; absolute alcohol, ro parts; 
water, go parts. Boil twenty minutes, cool and filter, and to each roo parts 
add 1 part of a cold saturated solution of lithium carbonate. 
The time for staining varies. In general, the longer the surer the result ; 
for cord sections, 2 or 3 hours are enough; in brain sections, 24 hours are 
required to color the very fine fibres of the cortex. 
After staining, the sections, now black in color, are differentiated by im- 
mersion in the following solution :—Borax, 2 parts ; ferricyanide of potassium, 
24 parts; water, 100 parts. Time here varies; for cord, 4 to several hours 
before desired contrast between the white and the grey is secured. In brain 
sections, longer. No fear of spoiling the sections need be felt. 
From this solution the sections are transferred to water and well washed, 
then to 80 per cent. alcohol, 90° F., spread on slides and dehydrated with too 
per cent., clarified preferably with xylol or creosote and mounted in xylol or 
benzole balsam. 
