34 ESSENTIALS OF BACTERIOLOGY. 



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 prevent- 

 ing too great a degree of heat). Since most of the specimens 

 contain a certain amount of albumenoid material, it is best in 

 all cases to " fix" it, i. e., to coagulate the albumen. This is 

 accomplished by passing the cover-glass (after the specimen 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. 11.) It prevents the flame 

 or staining-fluid from reaching the fingers. 



FIG. 11. 



Author's Bent Forceps for Hold ing Cover-glass over Flame. 



The object is now ready for staining. 



Staining. A few drops of the staining solution are placed 

 upon the cover-glass so that the whole specimen is covered, 

 and it is left on a few minutes, the time depending upon the 

 variety, the strength of stain, and the object desired. Instead 



