GENERAL METHOD OF STAINING SPECIMENS 37 



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

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

 of placing the dye upon the object, the cover-glass can be 

 immersed in a small glass dish containing the solution; or, if 

 heat is desired to intensify or hasten the process, a watch- 

 crystal holding the stain is placed over a Bunsen burner and 

 in it the cover-glass; the cover-glass may be held directly in 

 the flame with the staining fluid upon it, which must be 

 constantly renewed until the process is completed, or the 

 cover-glass can be heated in a test-tube, containing stain 

 solution. 



Fig. n. Author's bent forceps for holding cover-glass over flame. 



Removing Excess of Stain. The surplus stain is washed 

 off by dipping the glass in distilled water. 



The water is removed by drying between filter-paper or 

 simply allowed to run off by standing the cover-glass slant- 

 wise against an object. When the specimen is to be examined 

 in water (which is always best with the first preparation of 

 the specimen, as the Canada balsam destroys to some extent 

 the natural appearance of the bacteria), a small drop of ster- 

 ilized water is placed upon the glass slide, and the cover-glass 

 dropped gently down upon it, so that the cover-glass remains 

 adherent to the slide. 



The dry system or the oil immersion can now be used. 



When the object has been sufficiently examined, it can be 

 permanently mounted by lifting the cover-glass off the slide 

 (this is facilitated by letting a little water flow under it, one end 



