MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



Dissolve the alum in the water: then add the 

 celestin blue, and boil for three minutes. Cool 

 and filter ; then add the glycerine. 



H. Toluidine blue 0*5% aqueous. 



I. Orange G . . . . . . . . 2 gm. 



Phosphotungstic acid 5% aqueous. . 100 ml. 

 Allow to stand for 48 hours ; filter before use. 



Technique: 



1. Human and larger animal glands are bisected in the hori- 

 zontal plane with a sharp knife, and the two halves are fixed and 

 embedded separately. Rat hypophyses are fixed in situ after re- 

 moval of the brain and overlaying meninges, by immersing the 

 whole base of the skull in a beaker of the fixative. 



2. Fix in Helly for eighteen hours (man, goat, sheep), or two 

 to four hours (rat). 



3. Wash from six to twelve hours in running water. 



4. Dehydrate, clear and embed in paraffin wax. 



5. Cut sections 4-5/x (rat), or 5-5jLt (man). 



6. Fix sections to slides; remove paraffin wax with xylol and 

 pass through the usual descending grades of alcohol to distilled 

 water. 



7. Immerse in solution B for three minutes. 



8. Immerse in solution C (sodium thiosulphate) for three 

 minutes by which time the natural colour of the sections should 

 have been restored and mercurial precipitate removed from the 

 fixative. 



9. Wash well with water. 



10. Rinse with 70% alcohol. 



11. Immerse in periodic acid (solution D) for five minutes. 



12. Wash with 70% alcohol. 



13. Immerse in Hotchkiss' reducing rinse (solution E) for one 

 minute. 



14. Wash with 70% alcohol. 



15. Immerse in Feulgen's Fuchsin for ten to thirty minutes. 



182 



