170 BACTERIOLOGY. 



Staining with dahlia and decolorizing with sodium car- 

 bonate solution. Another method that is not very com- 

 monly employed, though the results obtained by its use 

 are in many cases very satisfactory, is to stain the tis- 

 sues iu a strong watery solution of dahlia (about one- 

 fourth saturated) for from ten to fifteen minutes; from 

 this they are transferred into a 2 per cent, solution of 

 sodium or potassium carbonate, and from this into alco- 

 hol, alternating from the one to the other until the sec- 

 tion is almost colorless. From the alcohol they are 

 rinsed out in water and then put into a dilute' watery 

 solution of either eosin, Bismarck-brown, or safranin for 

 one minute, then washed out in alcohol, finally in abso- 

 lute alcohol, and then in xylol, from which they may be 

 mounted in the manner given. 



Especially brilliant results are obtained when tissues 

 containing anthrax bacilli are stained by this process; 

 the bacilli will be of a deep blue color, while the sur- 

 rounding tissues will be.of the color used as contrast. 



Kuhne's carbolic methylene-blue method. Stain the 

 sections in the following solution for from one-half to 

 one hour: 



Methylene-blue, in substance 1.5 grammes. 



Absolute alcohol . 10 c.c. 



Rub up thoroughly in a mortar, and when the blue 

 is completely dissolved add gradually 100 c.c. of a 5 

 per cent, solution of carbolic acid. (The solution de- 

 composes after a short time; it should be made fresh 

 when needed.) From this the sections are washed out 

 in water, then in 1.5 to 2 per cent, hydrochloric acid 

 in water, from this they are transferred to a solution of 

 lithium carbonate of the strength of six to eight drops 

 of a concentrated watery solution of the salt to ten drops 



