DIFFERENTIAL STAINS IOQ 



5. Wash in water. 



6. Wash with alcohol until no more colour is dis- 

 charged and the alcohol runs away clear and colourless. 



The following mixture may be substituted for abso- 

 lute alcohol as a decolouriser 



Acetone 10 c.c. 



Absolute alcohol ^100 c.c. 



7. Wash in water. 



8. Counterstain very lightly with aqueous solution of 

 Neutral Red. Other counterstains may be used such 

 as dilute eosin, dilute fuchsin, or vesuvin. 



NOTE. This section may be omitted when dealing with films 

 prepared from pure cultivations. 



9. Wash in water. 



10. Dry and mount. 



Gram=Claudius Method. 



1 . Prepare a cover-slip film and fix in the usual way. 



2. Stain in methyl violet, i per cent, aqueous solution 

 for three to five minutes. 



3. Treat with two lots picric acid, saturated aqueous 

 solution. 



4. Wash in water and dry. 



5. Decolourise with clove oil. 



6. Wash off clove oil witk xylol. 



7. Mount in xylol balsam. 



Qram=Weigert Method. 



1-5. Proceed as for the corresponding sections of 

 Gram's method (quod vide) . 



6. Dry in the air. 



7. Wash in aniline oil, i part, xylol, 2 parts, until 

 no more colour is discharged. 



8. Wash in xylol. 



9. Mount in xylol balsam. 



