TUBERCULOSIS 141 



Sections of tissue are stained as under : 



1. The sections are treated with hot carbol-fuchsine solu- 

 tion for ten vninutes. 



2. Decolourise with 25 per cent, sulphuric acid,, dipping 

 the sections for about a minute or so into the acid and then 

 ivater alternately. 



3. Wash well in water. 



4. Gounterstain in solution Tnethylene blue for three 

 minutes. 



5. Wash slightly, then soak in absolute alcohol for two 

 minutes. 



6. Clear in xylol or oil of cloves. 



7. Transfer to glass slip with a section-lifter, blot with 

 filter-paper, and mount in xylol balsam,. 



By this method the bacilli are seen as bright-red slender 

 rods, which are on the average about three-quarters the 

 diameter of a blood corpuscle; The blue counterstaining 

 is not absolutely necessary, but it throws the bacilli into 

 greater relief Ribberts has proposed a method of reducing 

 the troublesome viscous character of tuberculous sputum 

 by a short boiling with a 2 per cent, solution of caustic 

 potash. 



Until ten or a dozen slides have been made and carefully 

 examined with negative results, we cannot safely assert 

 thap'the bacillus is absent. In doubtful cases it will be 

 safest to inoculate a guinea-pig with sputum, when posi- 

 tive results will be obtained. 



Pastor's Cultivation Method. — A gelatine tube is inoculated 

 with a fragment of a caseous particle, or, failing this, with 

 some sputum, well shaken and poured into a plate. 



After three or four days all the organisms except the 

 tubercle will have developed sufficiently to render them 

 visible ; when this has taken place, some of the clear spaces 

 of gelatine between the colonies are cut out and melted on 



