BACTERIOLOGICAL TECHNIQUE 35 



3. Wash the section in four or five changes of water. 



4. Into alcohol. 



5. Into Ehrlich's anilin water, gentian violet, or methyl violet 

 (see 55) one to two minutes. 



6. Remove section into Gram's iodine solution (see 60) for two 

 minutes, and spread the section well out. 



7. Into alcohol thirty seconds. 



8. Into 3 per cent. HC1. alcohol (see 70) for ten seconds. 



9. Now into alcohol many times until a maximal decolorization 

 is obtained, i.e., until no more colouring matter comes away. 



10. Into xylol one-half to one minute. 



11. Jiemove the excess of xylol with filter-paper, and mount the 

 section in xylol balsam. 



When the Gram method is used for sections without Professor 

 Giinther's modification, only the bacteria are stained, but by first 

 staining with picro-carmine a beautiful double-stained specimen is 

 the result, enabling the relation between the bacteria and the tissue 

 to be distinctly observed. 



The Gram method does not stain the cells except plasma or 

 granule cells, which are sometimes mistaken for clusters of micrococci. 

 Some of the epidermis cells also stain, and liver cells decolorize with 

 difficulty. 



The same bacteria are stained in sections by the Gram method as 

 are stained in cover-glass specimens (see 11). 



XXXIX. THE CLADIUS 'CONTRAST STAIN' FOR 

 SECTIONS. 



1. Stain the section with 1 per cent, watery solution of methyl 

 violet for two minutes. 



2. Wash in water, and dry with filter-paper. 



3. Into picric acid solution (see 61) for two minutes. 



4. Decolorize in clove oil, and dry with filter-paper. 



5. Into xylol. 



6. Mount in xylol balsam. 



This stain acts in a similar manner to Gram's method, and for 

 many bacteria it is preferable. For organisms stained by the method, 

 see Gram's method, 11. 



The original paper does not mention the method of applying the 

 clove oil ; but in conducting and testing the special action of this stain 

 it was found necessary to place the section on the slide during the 

 process of decolorizing w r ith the clove oil, to prevent its curling up. 



