36 ESSENTIALS OF BACTERIOLOGY 



Jenner's Stain. See page 189. 



/. H. Wright's stain: made in much the same way as 

 Irishman's. The precipitate is not washed, but the saturated 

 methyl-alcohol solution is filtered and further diluted with 

 methyl-alcohol. The stains are used in very dilute form. 

 Where the blood-films or exudates are not first fixed in alcohol, 

 the concentrated stain is allowed to cover the preparation for 

 five to twenty seconds to fix; then water is poured on to dilute 

 and from five to fifteen minutes allowed for staining, the excess 

 removed with water. The stains can be purchased in powder 

 form, and need only be mixed with water to be ready for use. 



CHAPTER V 

 GENERAL METHOD OF STAINING SPECIMENS 



Cover-glass Preparations. The material is evenly spread 

 in as thin a layer as possible upon a cover-glass; then, to spread 

 it still more finely, a second cover-glass is pressed down upon 

 the first and the two slid apart. This also secures two speci- 

 mens. Before they can be stained, they must be perfectly dry, 

 otherwise deformities will arise in the structure. 



Drying the Specimen. The cover-glass can be set aside to 

 dry, or held in the fingers over the Bunsen burner (the fingers 

 preventing too great a degree of heat). Since most of the 

 specimens contain a certain amount of albuminoid material, 

 it is best in all cases to "fix" i. e., to coagulate the albumin. 

 This is accomplished by passing the cover-glass (after the speci- 

 men is dry) three times through the flame of the burner, about 

 three seconds being consumed in doing so, the glass being held 

 in a small forceps, smeared side up. 



The best forceps for grasping cover-glasses is a bent one, bent 

 again upward, near the ends (Fig. 1 1) . It prevents the flame 

 or staining fluid from reaching the fingers. 



