PATHOLOGICAL APPEARANCES OF MYELITIS. 837 
removed, the cord is cut into pieces of an inch long but not 
entirely separated from one another, so that their relative 
position is still indicated. These are placed in the following 
solution for twenty-four hours : 
Chromic acid, 4ss ; 
Methylated spirit, 3xx ; 
Water, 3x. 
Dissolve the chromic acid i the water and then add 
the spirit. Place inan extremely cool situation, or if possible 
in an ice chamber. Change the fluid every second day for 
the first week, and at the beginning of the second week 
place it in the following solution : 
Chromic acid, 3ss ; 
Methylated spirit, 3x ; 
Water, 3xx. 
Allow it to le in this for another week, changing if a 
precipitate is thrown down. At the beginning of the third 
week change to the following : 
Chromic acid, 4ss ; 
Water, 3xxx. 
Change this every week until the end of the fifth or sixth, 
when the parts will be ready for cutting. This process is 
infinitely superior for all nervous tissues to anything that I 
have used, as the consistence of the tissue so hardened is 
tough instead of being brittle as in the old chromic acid 
method. For very large animals the solutions used are 
somewhat stronger. Cut extremely thin sections with a micro- 
meter screw apparatus, fixing the cord in the hollow cylinder 
by a piece of carrot, punched out by means of graduated cork 
cutters. Stain with the following : 
Carmine, 3] ; 
Liq. Ammonie fort., 3] ; 
Water, Ziv. 
Allow the sections to lie from five to ten minutes in this 
solution and then wash them in the following : 
Acetic acid, mvj ; 
Water, 3iv.} 
After this, wash them in pure water and place them in 
methylated spirit. Render them transparent with oil of 
cloves, and then mount them permanently in the following : 
Gum Dammar, 3]; 
Chloroform, 3iss ; 
Oil of cloves, 3). 
1 For all chromic acid preparations of the nervous centres it will be 
found that the specimens stain much more rapidly and thoroughly if the 
water in which they are washed is s/ightly acidulated. 
