126 PRACTICAL BACTERIOLOGY. 



(2) They are conveyed, after the superfluous stain- 

 ing material has been removed, into iodine dissolved 

 in potassic iodide solution (1 iodine, 2 potassic iodide, 

 300 water). After two minutes 



(3) They are placed in absolute alcohol (the sections 

 being carefully spread out), until no more colour is 

 given off. 



(4) They are examined in water. 



According to Giinther, the sections, after having been 

 removed from the alcohol (III. 3), may be placed for 

 ten seconds in alcholic solution of hydrochloric acid 

 (3 hydrochloric, 100 alcohol), from which they are 

 conveyed into absolute alcohol. In this way the nuclei 

 of the animal tissues are completely decolourised, 

 whilst the bacteria do not practically lose any of the 

 intensity of their colour. Gram's method is also suit- 

 able for the demonstration of tubercle bacilli. 



