50 BACTERIOLOGY. 



tions can also be obtained as in Ehrlich's method 

 for staining tubercular sputum, or by staining with 

 eosin after treatment by the method of Gram. 



Ehrlich's Method is as follows : Five parts of 

 aniline oil are shaken up with one hundred parts of 

 distilled water, and the emulsion filtered through 

 moistened filter paper. A saturated alcoholic solu- 

 tion of fuchsine, methyl violet, or gentian violet, is 

 added to the filtrate in a watch-glass drop by drop 

 until precipitation commences. Cover-glass pre- 

 parations are floated in this mixture for fifteen 

 minutes to half an hour, then washed for a few 

 seconds in diluted nitric acid (one part nitric acid to 

 two of water) and then rinsed in distilled water. 

 The stain is removed from everything except the 

 bacilli, but the ground substance can be after- 

 stained, brown if the bacilli are violet, or blue if 

 they have been stained red (Plate XX., Fig. i). 



Double staining with eosin after the method of 

 Gram is described under tissue staining. The 

 cover-glass preparations are treated by the same 

 processes as employed with sections ; superfluous oil 

 of cloves can be removed by gently pressing the 

 cover-glass between double layers of filter paper. 



Babes' Method affords a very rapid means of 

 examining cultivations, etc. A little of the growth, 

 removed by means of a sterilised platinum hook or 

 small ose, is spread out on a cover glass into as thin 

 a film as possible : when almost dry, a drop or two 

 of a weak aqueous solution of methyl violet is 



