VARIOUS STAINING PROCESSES 75 



the cover-glass, which is then washed in water, dried, again 

 passed three times through the flame, and mounted in 

 Canada balsam and xylol. 



Weichselbaum's method. This is a modification of the 

 Ziehl-Neelsen method, in which the red-stained cover-glass 

 preparations are transferred directly to an alcoholic methyl 

 blue solution, in which they remain until they show an 

 even blue colour. They are then rinsed in water, dried, 

 and mounted in Canada balsam. The alcohol is here the 

 only bleaching agent. 



Fraenkel's method, The cover-glasses are stained with 

 aniline water fuchsine and transferred to a fluid consisting of 

 a saturated solution of methyl blue in 50 parts water, 30 

 parts alcohol, and 20 parts nitric acid. When the preparation 

 appears blue it is washed in alcohol and acetic acid or in 

 pure water, and is examined in water. 



Gabbet's method. After staining in carbolic acid fuchsine 

 the preparation is brought into a sulphuric acid methyl 

 blue (2 grms. methyl blue to 100 grms. of a 25 per cent, 

 solution of sulphuric acid), and double stained with mala- 

 chite green. 



Method of Pfuhl and Petri. The preparations are stained 

 in a mixture of 10 c.cm. alcoholic solution of fuchsine to 

 100 c.cm. of water, and subsequently decolorised in glacial 

 acetic acid. They are then washed in water and double 

 stained with malachite green, again washed in water, dried, 

 and mounted in Canada balsam. In this case the glacial 

 acetic acid is the decolorising agent. 



Method of Pittion. The cover-glass preparation is dipped 

 for a minute into a mixture of 1 part alcoholic fuchsine 

 solution with 10 parts of a 3 per cent, solution of ammonia, 

 and transferred after rinsing in water to a concentrated 

 solution of aniline green in 50 grms. alcohol, 30 grms. water, 

 and 20 grms. nitric acid, in which it remains J minute. 



