542 BACTERIOLOGY. 



The section is transferred from eosin to absolute alco- 

 hol for 1 or 2 minutes. When thoroughly dehydrated it is 

 placed in oil of cloves, and should be allowed to remain in 

 this oil till all the violet color has been taken out of the 

 section. The sections may remain in this oil over night 

 without removing- the stain from the bacteria. The section 

 is then passed through two dishes of xylol, transferred to 

 a slide and mounted in Canada balsam. The deep violet 

 organism should stand out in bold relief against a light 

 pink back-ground. 



The section when placed in iodine tends to curl and 

 easily breaks. Very thin sections, therefore, should be 

 fixed on a cover-glass previous to the exposure to iodine. 



The following- summary of the simple and of the Gram 

 method of staining- will be useful: 



Simple Stain. Gram's Stain. 



Dil. anilin stain (5 to 15 min.). Anilin-water gentian violet, 



Wash in Water (2 to 3 min.). (10 to 15 min.). 



Acetic water (1-1 min.). Wash in water. 



Strong- alcohol (i-1 min.). Iodine solution (3 to 5 min.). 



Water and examine. Decolor in absolute alcohol. 



Absolute alcohol (few sec.). Very dilute eosin (i min.). 



Oil of cloves, or cedar. Dehydrate in abs. alcohol, 



Xylol. (1 to 2 min.). 



Mount in Canada balsam. Oil of cloves (till decolored). 



Xylol. 



Mount in Canada balsam. 



The process of simple staining- is a general method 

 which is appliable to nearly all bacteria. It must there- 

 fore be resorted to whenever the org-anism does not take the 

 Gram's stain (p. 290). 



In some instances, where Gram's method fails owing- to 

 the removal of the dye from the org-anism by the alcohol, 

 the so-called WeigerV s fibrin stain can be used to advantag-e. 

 The cover-glass preparations or sections are stained for 5 

 minutes or more in anilin-water gentian violet, then rinsed 



