DOUBLE STAINING 121 



Schallibaum's solution: 



Clove oil 30 c.c. 



Collodion 10 c.c. 



Keep in a dark blue bottle in a cool place. 

 Staining Paraffin Sections. 



1. Warm paraffin section over the Bunsen flame to 

 soften (but not to melt) the paraffin, then dissolve out 

 the wax with xylol poured on from a drop bottle. 



2. Remove xylol by flushing the section with alcohol. 



3. If the tissue was originally "fixed" in a corrosive 

 sublimate solution, the section must now be treated 

 with Lugol's iodine solution for two minutes and sub- 

 sequently immersed in 90 per cent, alcohol to remove 

 all traces of yellow staining. 



4. Wash in water. 



5. Stain deeply, if using a single stain, as the subse- 

 quent processes decolourise. 



6. Wash in water, decolourise if necessary. 



7. Flood with several changes of absolute alcohol to 

 dehydrate the section. 



8. Clear in xylol. (Oil of cloves is not usually em- 

 ployed, as it decolourises the section.) 



9. Mount in xylol balsam. 



SPECIAL STAINING METHODS FOR SECTIONS. 

 Double=staining Carmine and Gram=Weigert. 



1. Prepare the section for staining as above, sections 

 i to 3. 



2. Stain in lithium carmine (Orth's) or picrocarmine 

 for ten to thirty minutes, in a porcelain staining pot 

 (Fig. 76). 



3. Wash in picric acid solution until yellow. At 

 this stage cell nuclei are red, protoplasm is yellow, and 

 bacteria are colourless. 



Picric acid solution is prepared by mixing 



Picric acid, saturated aqueous solution . 40 c.c. 



Hydrochloric acid i c.c. 



Alcohol (90 per cent.) 160 c.c. 



