TRYPTOPHANE AND TYROSINE 59 



and Romieu (1931) presented evidence that the effect was the 

 result of tryptophane groups in the protein. As in the other protein 

 tests, the drastic nature of the reaction seriously interferes with its 

 use in most instances, as does the diffusibility of the color formed. 



Romieu Reaction for Tryptophane in Proteins 



SPECIAL REAGENTS 



Syrupy Phosphoric Acid. 



PROCEDURE 



1. Fix tissue in alcohol, formalin, or Bouin fluid. 



2. Prepare fairly thick paraffin or celloidin sections and remove 

 the infiltrating agent. 



3. Place a drop of the phosphoric acid on a section and set in 

 an oven at 56° for a few min. 



4. Examine on removal from oven. 



Result. A positive test is manifest by the formation of a red or 

 violet color. 



TYROSINE IN PROTEINS 



Bensley's histochemical adaptation of well-known Millon reac- 

 tion for proteins containing tyrosine has been employed in studies 

 by Bensley and Gersh ( 1933b) . 



Millon Reaction for Tyrosine in Proteins 

 (after Bensley and Gersh) 



SPECIAL REAGENTS 



Millon Reagent. Add 1 vol. 40% nitric acid (add 600 ml. distilled 

 water to 400 ml. cone, nitric acid, sp. gr. 1.42; let stand for 48 

 hr.) to 9 vol. distilled water and saturate with mercuric nitrate 

 crystals by frequent shaking over several days. Filter, and, to 400 

 ml. of filtrate, add 3 ml. 40% nitric acid and 1.4 g. sodium nitrite. 



1 % Nitric Acid. 



PROCEDURE 



1. Mount sections on slides without using water. The freezing- 

 drying technique is preferable. 



2. Place in cold Millon reagent. Since the maximum color is 

 developed in about 3 hr., remove each slide at a different time, dip 



_(Ll$ii^ARY 



