42 MANUAL OF BACTERIOLOGY. 



tached to the slide with glycerin-albumen. The different steps 

 in the process follow in the same order. The stain may be 

 poured on the slide, or the slide may be placed in a large dish 

 full of staining fluid. (See page 29.) Celloidin sections may 

 also be stained on the slide. If the section be well spread and 

 flattened thoroughly with blotting-paper, it will usually ad- 

 here to the slide, and is less likely to wrinkle. It must not be 

 allowed to dry. 



Gram's Method may be applied to the staining of sections 

 of tissues as well as to smears upon cover-glasses. 



(a) Place the section in aniline-water gentian-violet, five 

 minutes or longer. See the preceding paragraph for the 

 manner of handling sections. 



(b) Rinse in water. 



(c) Iodine solution (see page 31), one and one-half minutes. 



(d) Alcohol, until decolorized to a faint blue-gray. 



(e) Xylol. 



(/) Mount on a slide in balsam. 



Weigert's Modification of Gram's Method.— (a) Place 

 the section in aniline-water gentian- violet solution, five minutes 

 or more. See page 41 for the manner of handling sections. 



(b) Rinse in water. 



(c) After placing the section upon a slide, and having 

 straightened it carefully, absorb the water with blotting-paper. 



(d) Iodine solution (see page 31), one to two minutes. 



(e) Absorb the iodine solution with blotting-paper. 



(/) Add aniline oil, removing it from time to time with blot- 

 ting-paper, and adding fresh aniline oil until the specimen 

 becomes a faint blue-gray and until the color ceases to come 

 away. (Aniline oil serves in this connection both to decolorize 

 and to dehydrate. It absorbs the water rapidly and efficiently. 

 However, on account of its decolorizing tendency, it must be 

 removed before the specimens can be mounted permanently.) 



(g) Wash in several changes of absolute alcohol. 



