SYSTEMATIC AND DESCRIPTIVE. 157 



METHODS OF STAINING THE BACILLUS ANTHRACIS. 



Cover-glass preparations of blood, etc., can be stained 

 with a watery solution of any of the aniline dyes. They 

 may be rapidly stained with a drop of fuchsine or gentian- 

 violet (p. 46), but more satisfactorily by floating the 

 cover glasses for twenty-four hours. The preparations 

 may be dried and mounted in Canada balsam, but the 

 typical appearances are best observed in freshly stained 

 specimens examined in water. 



The sheath and protoplasmic contents can be differen- 

 tiated by staining with eosin after the method of Gram. 



The spores are not stained by the ordinary methods. 

 The cover-glass preparations must be raised to a high 

 temperature in the incubator, or treated with sulphuric acid 

 (p. 148), or passed about twelve times through the flame of 

 the Bunsen burner. 



Tissue sections are best stained by the method of Gram, 

 and after-stained with eosin, picrocarminate of ammonia, or 

 picro-lithium- carmine. 



A more rapid double stain is obtained by immersing the 

 sections in a watery solution of gentian-violet, rinsing in 

 alcohol, and then staining by the method of Orth (p. 58). 



Weigerts Method. Place the sections for two to five 

 minutes in a I per cent, watery solution of gentian-violet. 

 Wash in alcohol, rinse in water, and transfer to picro- 

 carmine solution (Weigert) for from a half to an hour t 

 Treat with alcohol till the colour is almost washed out 

 and finally clear in oil of cloves and mount in Canada 

 balsam. 



Bacillus ulna, Cohn. Cocci, short rods, long 

 rods, and threads. Diam. of the cocci 1*5 2*2 p.. 

 Spore formation in both short and long rods. No 



