EXAMINATION OF BACTERIA WITH THE MICROSCOPE. 45 



age. At the time of using, filter and dilute with water as 

 desired. 



Lithium-carmine (Orth). 

 Carmine .... . 2.5 grams. 



Saturated watery solution of lithium carbonate. loo.o c.c. 



Bacteria occasionally stain with hematoxylin -though as a 

 rule but faintly. The stain is not used for bacteria but only 

 for staining the nuclei of the tissue cells. 



Add a few crystals of thymol. The carmine dissolves 

 readily in the lithium carbonate solution. Filter the stain at 

 the time of using. Sections are to be left in the stain five to 

 twenty minutes. 



Sections stained in carmine are placed directly in acid 

 alcohol (i part hydrochloric acid, loo parts 70 per cent, alcohol) 

 for five to ten minutes. They acquire a brilliant scarlet color. 

 When used as a contrast-stain for tissues containing bacteria, it 

 is best to use it before staining the bacteria, which might be 

 decolorized by the acid alcohol. The sections should for this 

 reason be thoroughly washed before applying the Gram stain. 



Staining of Blood-films. — Romanowsky Stain.— There are 

 various modifications of this stain. MacNeaP states that the 

 following formula gives the best result for physicians and for 

 clinical laboratories: 



Prepare crude methylene violet by boiling for 15 minutes 

 over a free flame 0.5 grams of methylene azure, 0.5 grams of 

 sodium carbonate in 200 c.c. of distilled water. Cool slightly 

 and filter. The crude methylene-violet separates out from the 

 filtrate on cooling. Dry the crystals thoroughly. 



Of the above crude methylene-violet. 0.08 gr. 



Of methylene-blue (med. pure) . . 0.08 gr. 



Of eosin (water soluble yellowish) . 0.20 gr. 



Dissolve in 160 c.c. of methyl alcohol, filter, and dilute with 

 10 c.c. of methyl alcohol. The method of use is as follows: 

 *MacNeaI. Journ. Infectious Diseases. Vol. 3, 1906, pp. 412-433. 



