36 METHODS OF EXAMINATION. 



minutes (tubercle sections should be left for from twelve to twenty-four 

 hours), wash in alcohol for three minutes, and then in a solution 

 of ten parts iodine, twenty parts iodide of potassium, and 3000 parts 

 of water, until the dark blue violet is replaced by a dark purple red. 

 Wash in alcohol until most of the colour has disappeared, then clear 

 up in oil of cloves until still more of the colour is removed. The 

 sections may be mounted at once in balsam when the tissues and 

 nuclei have a faint yellow tinge, and the micro-organisms are deep 

 blue or almost black ; or they may be stained with a deeper contrast 

 stain, such as an alcoholic solution of eosin or Bismarck brown, or a 





"?> 







Fig. 5. — Bacillus anthracis. Stained by Gram's method with 

 methyl violet and vesuvin. Mounted in Canada balsam. ( x 700.) 

 Anthrax rods and filaments stained with the methyl violet. Some 

 spores are seen as bright points in the rods. Cells from pulp of 

 spleen of cow from which specimen was taken are stained brown 

 by the vesuvin. 



watery solution of vesuvin. Cover-glasses, with their films of sputum, 

 &c., after being prepared (see § 22, p. 26) are treated in exactly the 

 same manner as sections. 



