112 Manual of Veterinary 31icrobiology. 



avoided in another way ; to this end, the section, after 

 coming from the iodine, or even before staining, is 

 spread out, moist, upon the glass and fixed there in 

 a state of semi-desiccation by slightly heating it or 

 by the aid of tissue paper. On the section, thus 

 fixed, are then deposited in succession a drop of the 

 different reagents, the excess of each being carefully 

 removed with the tissue paper before replacing it 

 with the next. 



In the methods of Gram and Weigert as well as in 

 the method by Xiihne's violet, which we will consider 

 later, the iodine solution of Gram may be replaced by 

 the following : 



Corrosive sublimate, ... 1 gram. 



Water, . . . . . .100 grams. 



Alcohol, enough to dissolve. 



All microbes do not take indifferently the colora- 

 tions obtained by the above methods. For a given 

 germ one method may be more suitable than another ; 

 the manner in which the microbes behave toward the 

 different methods of staining is, indeed, utilized in 

 distinguishing them. But it is often desirable first 

 of all to determine whether or not a given substance 

 contains any germs. We attain this end by the fol- 

 lowing method : 



Kilhne^s method. — Kiihne has succeeded in stain- 

 ing nearly all microbes by employing two processes 

 in succession, one with methylene blue, and the other 

 with crystal violet. Some microbes are colored only 

 by the blue (typhoid bacillus), others only by the 

 violet (bacillus tuberculosis, bacillus of leprosy) ; 

 others, again, and these are the most numerous, take 

 the two colors indiflerently. 



