STAINING, PRACTICAL AND THEORETICAL 



4. Flood with the stain and allow it to act for fifteen to thirty 

 seconds ; then pour off the stain and wash rapidly in water. 



5. The preparation is then passed directly into absolute alcohol, 

 where it is allowed to remain only as long as the stain continues to 

 be washed out in clouds. 



6. Clear in xylol and mount. 



Results: 



Plasma cells: cytoplasm, brilliant crimson: nuclei, bluish- 

 green. Other cells appear in lighter shades of green and 

 crimson. 



Notes: 



(a) Sometimes the brilliancy of the stain is enhanced by re- 

 staining. 



(b) Readers requiring more detailed information should consult 

 the original paper which shows seven photomicrographs. 



Reference: Hitchcock, C. H. & Ehrich, W. (1930)- 



INDOLE REACTION (Ehrlich) 

 For tryptophane 



Solution required: 

 Ehrlich's indole reagent 



Technique: 



1 . Frozen or paraffin sections are taken to distilled water. 



2. Immerse in the reagent for one to two hours at 60° C, in a 

 stoppered staining jar (which should be only partially filled to 

 allow room for expansion and vaporization of the alcohol con- 

 tained in the reagent). 



3. Take the jar out of the oven and allow it to cool for about 

 ten minutes. 



4. Rinse the sections in absolute alcohol. 



5. Clear rapidly in xylol. 



6. Mount in D.P.X,, Cristalite, or Clearmount. 



248 



