STAINING IN TISSUES. 321 



joiuts become swollen and infiltrated to such an extent 

 as often to interfere with the use of the legs. In male 

 animals the testicles become enormously distended with 

 pus, and on closer examination a true orchitis and epi- 

 didymitis are seen to be present. The internal organs, 

 particularly the lungs, kidneys, spleen, and liver, are 

 usually the seat of the nodular formations characteristic 

 of the disease. From all of these disease-foci the 

 bacillus causing them can be isolated in pure culture. 



Staining in Tissues. — -Though always present in 

 the diseased tissues, considerable trouble is usually ex- 

 perienced in demonstrating the bacteria by staining- 

 methods. The difficulty lies in the fact that the bacilli 

 are very easily decolorized, and in tissues stained by the 

 ordinary processes are robbed of their color even by 

 the alcohol with which the tissue is rinsed out and de- 

 hydrated. If we will remember not to employ con- 

 centrated stains, and not to expose the sections to the 

 stains for too long a time, but little treatment with 

 decolorizing-agents is necessary, and very satisfactory 

 preparations will be obtained. A number of good 

 methods have been suggested for staining the glanders 

 bacilli in tissues, and if what has been said will be 

 borne in mind, no difficulty should be experienced. 



Two satisfactory methods that we have used for this 

 purpose, though perhaps no better than some of the 

 others, are as follows : 



(a) Transfer the sections from alcohol to distilled 

 water. This lessens the violence with which the stain 

 subsequently takes hold of the tissues, by diminish- 

 ing the activity of the diffusion that would occur if 

 they were placed from alcohol into watery solutions of 

 the dyes. Transfer from distilled water to the slide. 



