STAINING, PRACTICAL AND THEORETICAL 



(iii) Place i ml. of solution C (iodine solution) in a small 

 tube. 



(iv) Draw up and hold 2 ml. of Schiff 's solution, prepared 

 as above, in a pipette graduated in o-i ml. 



(v) Drop Schiff's reagent from the pipette into the tube 

 containing the i ml. of iodine test solution, cautiously, 

 shaking the tube after each addition, until the iodine is de- 

 colorized and note what volume of the Schiff reagent is re- 

 quired. Best results are obtained when 0-8-2 ml. of the 

 Schiff reagent is required to decolorize i ml. of the iodine 

 solution. To achieve this it may be necessary, depending 

 upon how recently the Schiff reagent has been prepared, 

 to reduce the amount of sulphur dioxide present in the 

 solution by heating (in a fume cupboard) or by mixing with 

 a Schiff solution already depleted by continued use. 



H. Orange G . . . . . . . . 3 gm. 



Distilled water . . . . . . 100 ml, 



HCl, cone. . . . . . . I ml. 



Note: 



Elftman states that the pH of the orange 03% aqueous should 

 be adjusted to 2-0 with HCl. In my laboratories, using orange 

 G (Michrome No. 411), it was found that a 3% aqueous solution 

 of this dye (in distilled water at pH 7*0) registered a pH 8-75 

 and it was necessary to add i ml. of N/i HCl to reduce the pH 

 of the staining solution to 2-0. In other laboratories, the amount 

 of acid necessary will vary according to the pH of the distilled 

 water available, and possibly the make of dye used. 



Techiiique: 



1. Remove the pituitary from the animal and fix in solution B 

 (freshly prepared) at room temperature overnight, although the 

 time may be prolonged up to forty-eight hours. 



2. Transfer to 70% alcohol. 



3. Dehydrate, clear, and embed in parafHn wax as usual. 



4. Cut sections at 5 ju. and attach them to slides. 



5. Remove paraffin wax with xylol. 



6. Carry through the usual graded alcohols into water. 



7. Treat with 1% iodine in 70% alcohol for ten minutes. 



120 



