STUDIES ON THE PANCREAS OF THE GUINEA PIG 309 



having the color of a good haemalum solution is obtained. Allow 

 this solution to stand twenty-four hours to permit the excess dye 

 to separate out, when it may be employed for staining as follows : 



Stain in neutral gentian solution 24 hours. 



Blot between several layers of filter paper. 



Dehydrate in acetone. 



Place section in toluol. 



Differentiate in: 



Absolute alcohol 1 part 



Oil of cloves 3 parts 



Wash with toluol and mount in balsam. 



b. The safranin-acid violet method. Prepare the stain by pre- 

 cipitating a saturated solution of safranin O with solution of 

 acid violet. The precipitation should be complete, leaving on 

 subsidence a faintly violet supernatant fluid. Dissolve this 

 precipitate in absolute alcohol. To make the solution for stain- 

 ing, dilute this stock solution with its own volume of distilled water, 

 allow to stand thirty minutes, then filter and use. 



The method of using this solution is the same as for neutral 

 gentian except for the fact that staining is from five to thirty 

 minutes. 



c. The acid fuchsin methyl green method. This method has 

 much in common with the well-known method of Galeotti but is 

 somewhat simpler. 



The staining solutions are : 



1. Altmann's acid fuchsin anilin solution: 



Acid fuchsin 20 grams 



Anilin water 100 cc. 



2. 1 per cent solution of methyl green. 



The sections after being prepared for the staining process by 

 treatment with permanganate of potassium followed by oxalic 

 acid, are stained for five minutes in the acid fuchsin solution which 

 has been previously warmed to 60° C. Then they are thoroughly 

 washed in distilled water, and dipped for an instant into the 

 solution of methyl green, then washed, rapidly dehydrated in 

 absolute alcohol (alcohols of intermediate strength must be 



