158 TUBERCULOSIS. 



are straight or curved, and frequently beaded, occur singly, in pairs 

 or in bundles. In the tissues they are found in the interior of 

 giant cells and within and between epithelioid cells. The bacillli 

 of tuberculosis are non-motile and consequently possess no power of 

 locomotion and cannot penetrate into the tissues without assistance. 

 Spore-formation occurs, even within the animal body, the spores 

 having the appearance of clear vacuoles. 



METHODS OF STAINING. For section-staining Ehrlich's method 

 is the best : 



Saturated alcoholic solution of methyl-violet or fuchsin 11 parts. 



Aniline water 100 " 



Absolute alcohol .... . . . 10 " 



Sections are left for twelve hours in this solution. Treat the 

 specimen with 1 : 3 solution of nitric acid a few seconds. Wash 

 in alcohol (60 per cent.) for a few minutes; after-stain with diluted 

 solution of vesuvin or methyleue-blue for a few minutes ; wash 

 again in 60 per cent, alcohol, dehydrate in absolute alcohol, clear 

 with cedar oil, mount in Canada balsam. The examination of 

 fluids can be done rapidly and most satisfactorily by Gibbes 7 

 method. 



Gibbes 7 magenta solution : 



Magenta 2 parts. 



Aniline oil 3 " 



Alcohol (specific gravity 0.830) 20 " 



Distilled water 20 " 



Stain cover-glass preparations in this solution for fifteen or 

 twenty minutes ; wash in (1 : 3) solution of nitric acid until the 

 color is removed ; rinse in distilled water. After-stain with 

 methyleue-blue, methyl-green, iodine-green, or a watery solution of 

 crysoidin, five minutes ; wash in distilled water until no more color 

 comes away. Transfer to absolute alcohol for five minutes, dry, 

 and preserve in Canada balsam. 



CULTIVATION EXPERIMENTS. -The best culture medium is 

 solid sterilized blood-serum of the cow or sheep, with or without 

 the addition of gelatin at a temperature of 37 to 38 C. (98.6 to 

 100.4 F.). The bacillus grows very slowly and only between the 

 temperatures of 30 and 41 C. (86 and *105.8 F.). In about 

 a week or ten days, the culture appears as little whitish or yellowish 

 scales and grains. The bacillus can also be cultivated in a glass 

 capsule on blood-serum, and the appearance of the growth studied 

 under the microscope. The scales, or pellicles, are then seen to be 

 made up of colonies of a perfectly characteristic appearance. The 

 growth ceases after three or four weeks. The blood-serum is not 

 liquefied, unless putrefactive bacteria contaminate the culture. 



