i.] MICROSCOPIC EXAMINATION. 13 



A. Gottstein 1 places sections of syphilis material for 

 twenty-four hours in fuchsin or aniline oil gentian-violet ; 

 wash with distilled water, then place them for a few seconds 

 into a pure or dilute solution of liquor ferri, then wash in 

 alcohol, clarify in clove-oil, mount in Canada-balsam. 



It may not be unnecessary to point out, that if sections are kept for 

 many hours in the staining fluid, there may be found in them micro- 

 organisms (particularly bacilli) which have been accidentally introduced 

 into them by the solutions of aniline dye. Many of these, particularly 

 when used alkaline, contain organisms, and if the sections are kept 

 in them for many hours, notably in warm weather, bacteria will be 

 found to have not only invaded the tissue but to have multiplied 

 therein. 



In examining fresh or hardened tissues for micro-organisms 

 it is necessary to make thin sections, which can be easily 

 done with the aid of any of the microtomes in common use, 

 amongst which Williams's microtome, and especially Dr. 

 Roy's ether-spray freezing microtome, are no doubt the best 

 and easiest to manipulate. As regards hardened material, it 

 is necessary to remember that the hardening must be carried 

 out properly, small bits about a half to one cubic inch of 

 tissue being placed in alcohol, or better, in Miiller's fluid, and 

 kept there ; in the first instance, for two to five days ; in the 

 second, for from one to three weeks or more. Then small 

 bits are cut out, of which it is desired to make sections. 

 Those hardened in spirit must be soaked well in water to 

 enable the material to freeze, then superficially dried with 

 blotting-paper, and then used for cutting sections with Roy's 

 microtome. Those hardened in Muller's fluid are at once 

 superficially dried with blotting-paper and cut. When 

 making sections with Williams's freezing microtome it is 

 necessary to soak the material first in gum mucilage and then 



1 A. Gottstein, Fortschrittc d. Medizin, Berlin, 1885, No. 16, p. 545. 



