134 BACTERIOLOGICAL LABORATORY TECHNIC 



I. Loffler's Method. 



(a) Float section in water. 



(6) Remove with section lifter to Loffler's methylene blue from five to 

 thirty minutes. 



(c) Decolorize in i percent solution of acetic acid for ten seconds. 



(d) Dehydrate in absolute alcohol for a few minutes. 



(e) Clear in xylol. 



(/) Mount in balsam. 



II. Weigert's Method. 



(a) Place in lithium carmine five minutes. 

 (6) Then in acid alcohol fifteen seconds. 



(c) Wash in water. 



(d) Transfer to slide and dry with blotting paper. 



(e) Apply Ehrlich's gentian violet for three minutes. 

 (/) Blot and place in Gram's solution for two minutes, 

 (g) Wash and dehydrate in aniline oil, 



(h} Wash with xylol. 



(i) Dry, mount in balsam and examine. 



In Loffler's method all the tissues, especially the nuclei and the 

 bacteria, appear blue. 



In Weigert's method, if the bacteria stain by Gram's method, 

 the tissues appear pink, the bacteria a deep blue-black. Tubercle 

 bacilli are to be stained in tissues, best fixed in formaldehyde solu- 

 tion, by heating with carbol-fuchsin as given on page 106; the sec- 

 tion is decolorized by 3-5 percent hydrochloric acid and cleared 

 by passing it through 95 percent alcohol, absolute alcohol and 

 finally xylol. It is then mounted in balsam. 



Parafnne embedding methods may be employed, but for these 

 and -other methods of staining the student is referred to works 

 solely devoted to technique. The staining methods are the 

 same for paraffine and in experienced hands give better results. 



