42 METHODS OF EXAMINATION. 



minently as deeply stained rod-shaped bodies. It is, however, ex- 

 tremely difficult to observe the relations of these rod-shaped bodies 

 to the tissues in vfhich they lie, especially when they are present in 

 small numbers, or where they occur as single rods scattered at great 

 intervals. In order to obviate this difficulty, a second or contrast 

 colour is used, a colour which will stain the nuclei and cells deeply, 

 and which will also serve as a background to bring into relief the 

 bacilli. 



If the bacilli are stained with methyl blue or gentian violet. 



> >^ 







Fig. 9. — Tubercle bacilli in sputa. Stained with gentian violet. 

 Contrast stain Bismarck brown. Weigert's method. ( x 450.) 



Bismark brown or vesuvin forms the best contrast stain ; with magenta 

 or fuchsin methyl blue is preferable. 



Since Weigert, Ehrlich, and Koch worked at these methods, there 

 have been innumerable modifications, most of which have for their 

 object the simplification and shortening of the process, and are 

 specially devised for the use of clinicians. 



28. RiiidfleiscK s method. — First prepare a solution as follows : — Satu- 

 rated alcoholic solution of fuchsin, ten drops ; aniline water, freshly 

 prepared and filtered, two drachms. Pour this into a watch-glass, and 

 place the cover-glass prepared face downwards on the surface ; with 

 a pair of forceps hold the watch-glass over a spirit lamp or other 

 flame until steam rises from the surface of the staining fluid. 

 Remove the cover-glass with a pair of forceps ; wash off the super- 



