300 TITRIMETRIC METHODS 



13. Add a little thymol blue soln. and bring to a bluish-grey 

 color with 1 A'' sodium hydroxide. If the end point is passed, bring 

 to the proper color with 0.1 N hydrochloric acid. 



14. Set up a control by neutralizing 35 fxi. 0.6 N hydrochloric 

 acid to thymol blue. 



15. Determine the glucose by the method of Linderstr0m-Lang 

 and Holter (page 269). 



Hcatley and Lindahl Method for Desmo- and Lyoglycogen 



SPECIAL REAGENTS 



The same as in the preceding method for total glycogen. 



PROCEDURE 



1. Place the tissue in a little distilled water in a tared reaction 

 tube cooled by ice. 



2. Plunge the tube into a current of steam, and shake it at 

 intervals for 10-15 min. while in the steam. A mechanical shaker 

 is recommended. 



3. Centrifuge, and transfer the supernatant to another tube. 



4. Add another portion of distilled water to the residue and 

 again heat and shake as before. 



5. Centrifuge, and add the supernatant to that previously 

 drawn off. 



6. Make one or two more extractions in the same way and 

 evaporate the water from both tubes. Dry the tubes at 100° for 

 2 hr. and reweigh. The sum of the increases in weight of the tubes 

 represents the dry weight of the tissue sample taken. The extracted 

 material contains the desmoglycogen and the material in the super- 

 natant is the lyoglycogen. 



7. Add 35 [A. 30% potassium hydroxide to the material in each 

 tube and proceed with the glycogen determination as previously 

 described. 



ASCORBIC ACID 



The method introduced by Tillmans and associates for the deter- 

 mination of ascorbic acid by titration with 2,6-dichlorophenoIindo- 

 phenol was applied by Glick ( 1935b) to measurements on microtome 

 sections of tissue. This micro method has a reproducibility of ±0.1 

 /Ltg. ascorbic acid. Since the publication of the procedure, the use of 



