176 ATLAS OF BACTERIOLOGY. 



and with sixty per cent alcohol for a few moments. 

 It is then dipped for several minutes in a watery 

 solution of Bismarck brown and washed off in water. 

 The tubercle bacilli then appear violet on a brown 

 background. 



In this form the method is suitable for cover-glass 

 preparations from pure cultures and tuberculous 

 sputum with many tubercle bacilli. If very few or no 

 bacilli are found in the first preparations, we must 

 adopt some method for increasing their numbers. 

 We mention two of the innumerable recommen- 

 dations : 



(a) According to Strohschein : 



Five to ten cubic centimetres of the sputum are 

 mixed with a threefold amount of Wendriner's borax- 

 boracic acid solution,* and after vigorous shaking 

 allowed to settle for four to five days. The mixture 

 becomes fluid and the bacilli settle at the bottom. 

 Such sputum may be used for examination even after 

 the lapse of years. 



(&) According to Dahmen, modified by Heim : 



The entire sputum is cooked from fifteen to twenty 

 minutes in a beaker glass in the steam chamber, then 

 allowed to cool, the opalescent fluid is poured off, and 

 the crumbly sediment is used for smear preparations. 



B. Section Preparations. 



1. Universal method, according to Loffler, adapted 

 to the large majority of bacteria. 

 The section, which lies in alcohol, is conveyed 



* Eight grams borax dissolved in hot water, 12 gm. boracic 

 acid added, and then 4 gr. borax ; after crystallization the solu- 

 tion is filtered. 



