I72 PRACTICAL PHOTO-MICROGRAPHY. 
organisms are deeply stained ; the same holds good 
with methyl-blue, but if these stains are only pale, and 
particularly if the sections are counter-stained, the 
trouble in getting a good plucky negative showing the 
relations of organisms to tissue is infinite. Methyl-blue 
is a special sinner in this respect, that it washes out 
very easily, and some clearing agents too often used, as 
clove oil, are apt to destroy it for photographic purposes. 
We much prefer, when it is possible, to stain the 
bacteria red, with fuchsin or dark violet, by Gram’s 
system, and to stain the tissue blue as with the “ Plas- 
mamethylene-blue,” or red with alkaline carmine, or 
yellow with benzo-purpurin, as the case may be. The 
bacteria, as seen in the microscope, must stand out 
boldly from the tissue ; if this is the case it is our 
business to overcome any colour-difficulty there may 
be. But if the bacteria do not stand out, it cannot be 
expected that we shall make them appear to do so in 
our photographs. For a good photo-micrograph, we 
repeat, we require a good preparation and photographic 
skill. 
The faintly alkaline methylene-blue of Loeffier stains 
cover-glass preparations and bacteria in sections beauti¬ 
fully, provided the preparations are not over washed. 
The same may be said of the carbolic blue (methyl) of 
Kiihne and others. Weigert’s method of making stains 
also answers well—anilin water—but we add alcohol in 
excess of the usual quantity. The addition of alcohol 
certainly tends to make the staining more discrete. 
When fuchsin—carbolic or anilin—-is used, the stain 
