SECTION TWO 



E. Solution A . . , . . . o-8 ml. 



Solution B . . . . . . 0-2 ml. 



Solution C . . . . . . i-i ml. 



Solution D . . . . . , 0*9 ml. 



Distilled water . . . . . . 37 ml. 



Technique: 



1. Slices of tissue 3-4 mm. in thickness are fixed in neutral 

 buffered 10% formalin or Lillie's (1954) " B-5 " fixative for 

 six to twenty-four hours. Zenker-formalin can be used instead, 

 but acetic-Zenker and Bouin's fixatives are stated to give poor 

 results. 



2. Wash in running water; dehydrate; clear; and embed in 

 paraffin wax as usual. 



3. Cut sections at 5/x, fix them to shdes; dewax and pass 

 through the usual graded alcohols down to distilled water. 



4. Immerse in a Coplin jar containing solution E at room 

 temperature, then immediately transfer the whole to an oven at 

 60° C, and leave the stain to act at that temperature for an hour. 



5. Wash in running water for five minutes. 



6. Dehydrate and clear through 50%, 80% and anhydrous 

 acetone, acetone xylol (i :i), xylene (two changes), and mount in 

 a synthetic medium such as Cristalite, Emexel, Clearmount, or 

 D.P.X. 



Note: The authors suggest cellulose caprate as a mountant, 

 but this product does not appear to be available in Britain, except, 

 as far as I am aware, in very small quantities, and at a cost which 

 would be considered wholly prohibitive by the vast majority of 

 biologists. 



Results: 



Beta-cell granules: blue-black. Acidiphil granules: dark red. 

 Chromophobe granules: slate grey to pale pink. Colloid: red to 

 bluish violet. Erythrocytes : orange. Collagen : blue. 

 Notes: 



(a) It is stated that no differentiation is necessary, and that the 

 above results are consistently obtained. 



(b) The authors state that the method can be modified for 

 duodenal enterchromaffin cells and alpha cells of the pancreatic 



191 



