168 ATLAS OF BACTERIOLOGY. 



scope. The immersion oil is always brushed off 

 gently, and now and then the lens is rapidly cleansed 

 with xylol and chamois skin; prolonged action of 

 xylol loosens the setting of the lens. Xylol also re- 

 moves dried particles of oil from the cover-glasses of 

 old preparations. 



2. THE MOST IMPORTANT SOLUTIONS FOR MAKING 

 PREPARATIONS. 



A. Staining Solutions. 



1. Watery alcoholic solution of fuchsin and methyl 

 blue. A concentrated "stock solution" is made by 

 pouring absolute alcohol over the powdered coloring 

 matters (fuchsin, methyl blue) in bottles, shaking, 

 letting them stand for a few hours, and then filtering. 

 Of this saturated solution one part is mixed with four 

 parts distilled water and filtered before using. In 

 order to obtain good preparations it is better to stain 

 for a longer time with weak solutions than for a 

 shorter time with strong solutions. 



2. Carbolized fuchsin (Ziehl's solution) : 



Fuchsin 1.0 gm. 



Acid, carbolic, liq 5.0 ' 



Alcohol 10.0 " 



Aq. dest 90.0 " 



3. Aniline fuchsin: 4.0 aniline oil (anilin. pur.) are 

 well shaken for several minutes with 100 aq. dest., 

 then filtered until all the water runs off clear (then 

 the funnel is removed because otherwise the oil will 

 pass through). In this aniline water are dissolved 4.0 

 gm. fuchsin and it is then again filtered. 



