GABBETT'S METHOD. 135 



other organisms with which it might be confounded. 

 A number of different methods have been suggested 

 for the staining of tubercle bacilli, but the original 

 method as employed by Koch is so satisfactory in 

 its results that it is not advisable to substitute others 

 for it. The above differs from the original Koch- 

 Ehrlich method for the staining of tubercle bacilli in 

 sputum only in the occasional employment of Ziehl's 

 carbolic-fuchsin solution and in the method of heating 

 the preparation with the staining fluid upon it. 



As Nuttall has pointed out, however, the strong acid 

 decolorizer used in this method can be with advantage 

 replaced by much more dilute solutions, as a certain 

 number of the bacilli are entirely decolorized by the 

 too energetic action of the strong acids. He recom- 

 mends the following method of decolorization : After 

 staining the slip or section in the usual way, pass it 

 through three alcohols ; it is then to be washed out in a 

 solution composed of 



Water 150 c.c. 



Alcohol 80 c.c. 



Concen. sulphuric acid 20 to 30 drops. 



From this they are removed to water and carefully 

 rinsed. The remaining steps in the process are the 

 same as those give^in the_ other methods. 



Gabbett's Method for the staining of tubercle 

 bacilli recommends itself because of its simplicity and 

 the rapidity with which it can be performed. By 

 many it is considered the best method for routine 

 employment. It consists in staining the cover-slips, 

 prepared in the manner given, for from two to five 

 minutes in a cold carbolic-fuchsin solution, after which 

 they are subjected to the action of Gabbett's methy- 



