STAINING SPORES 5 1 



Inoculate from a culture of Bacillus cholerce suis (furnished) ( 

 a tube of agar and place it in the incubator for the next exer-J 

 else. 



78. A Method for Staining Spores. — Make a cover-glass 

 preparation, dry, and flame as already described. Take the 

 preparation by the edge with the fine forceps, cover the film 

 surface with carbol fuchsin, and hold the preparation over the 

 gas flame until steam is given off, then remove it for a few sec- 

 onds and again heat it. Repeat the heating three or four 

 times. After the stain has acted for from 3 to 5 minutes, rinse 

 the preparation in water, and decolorize it by immersing it in 

 a watch-glass containing about 3 c.c. of a i % solution of sul- 

 phuric acid or of 95% alcohol. After about one-half minute 

 remove the preparation and rinse it thoroughly in water. If it 

 is not decolorized, repeat the bleaching process. This removes 

 the coloring matter from the bodies of the bacteria, but leaves 

 it in the spores. After thoroughly washing the preparation, 

 counter stain it with a saturated aqueous solution of methylene- 

 blue for about 30 seconds, rinse in water and examine. The 

 spores should be stained red (with the fuchsin) and the rest 

 of the organism should be colored blue. 



There is a very satisfactory method recommended by MoUer. 

 For this and other methods for staining spores, see text-books 

 on bacteriology. 



