ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
549 
immersion in the following solution, which must be renewed until all 
traces of sublimate have disappeared : — Tincture of iodine, 2 ; iodide of 
potash, 1 ; distilled water, 50 ; glycerin, 50. After this the piece is 
placed in pure glycerin, to every 100 ccm. of which 2 grm. of anhydrous 
sulphate of copper are added, Herein it remains for 24-48 hours. 
The preparation is then to be imbedded. For this it is first saturated 
with glycerin-jelly or transparent soap, and then inclosed in pretty hard 
paraffin ; but before this inclosure is made, the object must be immersed 
merely for a moment in quite absolute alcohol. Instead of inclosing 
in paraffin the object may be stuck on cork with thick jelly or jammed 
in liver. While sectioning it is necessary to cover both knife and 
preparation with a mixture of equal parts of water and glycerin, 
otherwise the section will be torn to pieces. The sections are then 
removed to water on a brush. The next step is to contrast stain, and 
for this purpose some of the various carmine solutions are most suitable. 
It is advised to place the sections for a quarter of an hour before staining 
in a saturated solution of lithium carbonate. If a single stain be desired, 
then alum-carmine or cochineal are suitable ; if a double stain, then 
neutral carmine followed by differentiation with weak acetic acid. The 
sections are then placed in glycerin and water (equal parts), and then 
saturated solution of picric acid is added. 
The sections are then transferred to pure glycerin and there examined. 
In successful preparations a triple stain is obtained, and we are enabled 
to ascertain how the pigment has acted during life, that is to say, what 
has been its distribution and effect; whether it has penetrated within 
the vascular channels, among the stroma of the tissue, whether it has 
obtained access to the interior of the cells, and what action it has had 
upon the epithelial cells. 
Preparing and Staining Sections of Spinal Cord.* -In a contri- 
bution to the technique required for spinal cord, Dr. A. Ciaglinski 
enunciates some apparently heterodox opinions, such as the uselessness 
of hsematoxylin for staining, and gives with copious details his method 
of procedure. The spinal cord is to be cut up into pieces 1 cm. long, 
and these immersed in Erlitzki’s fluid (3-4 weeks), or in Muller’s fluid 
(3-4 months). As the former solution is prone to throw down a copper 
precipitate, the latter is preferred. When sufficiently hard, the pieces 
are carefully washed in water, and then placed for a day or two in 
70 per cent, spirit, and finally for one day in absolute alcohol. Thus 
dehydrated, the object is immersed for 24 hours in anilin oil, then for 
2 or 3 hours in xylol. Then for 20 hours in a mixture of equal parts of 
xylol and paraffin, and kept at a temperature of 37° C., after which it is 
imbedded in pure paraffin. The paraffin, which for winter should have 
a melting-point of 45° C., and for summer of 52° C., is melted over a 
gas flame. To the first paraffin imbedding are added some drops of cedar 
oil to make it more elastic, and the preparation left in the oven for 
24 hours. The second imbedding is only incubated for 15-20 minutes, 
and then the preparation is turned out into a watch-glass smeared with 
glycerin. It is important to know which side is uppermost. The 
Zeitschr. f. Wiss. Mikr., viii. (1891) pp. 19-28. 
