202 BACTERIOLOGICAL DIAGNOSIS. 
water) and must be entirely removed with the same 
fluid before the section is mounted, or it will cause it to 
fade. Clove oil is a very powerful decolorising agent, 
and requires careful use, or the colour may be removed 
from the bacteria. 
7. Eosin—half a minute or more. This is a counter- 
stain, and is used to demonstrate the structural elements, 
which are not coloured by the gentian violet. It may 
be omitted in some cases. 
8. Absolute alcohol—two lots. To remove the water. 
g. Xylol—two lots, or until the section becomes trans- 
parent. 
10. Balsam and a cover-glass. 
This method of staining is very easy of application, 
and the results are exceedingly beautiful; bacteria 
which take the stain are coloured blue or violet, and 
actively-dividing nuclei and keratin are stained in the 
same way, while all other structures are stained 
pink. 
(3). Method for bacteria which do not stain by 
Gram’s method ; suitable for sections of typhoid ulcers, 
lymphatic glands containing plague bacilli, &c. 
The problem before us in this case is not at all easy 
of solution. In the first place, the stains which colour 
the bacteria also colour the tissues, especially the cell- 
nuclei; the bacteria are easy to stain, but it is difficult 
to stain a section in which there is good differentiation. 
In the second place, the stains which are used for 
bacteria are all soluble in alcohol; but alcohol is used 
to dehydrate the sections. The following method will 
be found to serve fairly well in most cases, though it 
requires a certain amount of practice for its successful 
accomplishment. 
I, 2, and 3. Xylol, alcohol, and water, as before. 
