STAINING, PRACTICAL AND THEORETICAL 



C. Solution B (as above) . . . . lo ml. 



Alcohol 20% . . . . Sufficient to impart a rich 



port-wine colour. 

 Allow to stand for twenty- four hours; then filter. 



D. Absolute alcohol . . . . i volume 

 Clove oil . . . . • • 3 volumes 



Technique: 



1. Tissues are fixed in Solution A (as above) for twenty-four 

 hours, and afterwards embedded in paraffin wax in the usual man- 

 ner. 



2. Stain sections for twenty-four hours in Solution C (as above) ; 

 then pour off excess stain, and blot the preparation carefully. 



3. Dehydrate by immersing in two or three changes of acetone. 



4. Clear in xylol; then differentiate in Solution D (as above), 

 controlling under the microscope. 



5. Rinse in two changes of xylol; then mount in balsam. 



Results : 



Zymogen granules, violet; granules of acidophil cells are 

 stained orange-red, while those of basophil cells are violet ; back- 

 ground, brown. 



Reference: Bensley, R. R. (1911). 



ORCEIN 



For staining myelin sheaths of human dental and 

 paradental tissues, etc. 



Solutions required: 



A. Formic acid, 10% aqueous 



B. Sodium citrate, 25% aqueous 



C. Solution A . . . . . . I volume 



Solution B . . . . . . I volume 



D. Orcein (Unna-Taenzer), page 329 



Technique: 



I. Fix adult teeth in 10% formalin, for at least seven days, 

 after cutting the radicular apex to facilitate penetration of the 

 fixative into the pulp. 



328 



