44 MICROSCOPIC TECHNIQUES 



will not give the reaction and cerebrosides, if present, would be 

 expected to react. 



Method of Hotchkiss for Polysaccharides 



SPECIAL REAGENTS 



Periodic Acid Solution A. Dissolve 400 mg. periodic acid (H5IO6, 

 obtainable from G. Frederick Smith Chemical Co.) in 10 ml. dis- 

 tilled water, add 5 ml. M/5 sodium acetate and 35 ml. alcohol. 

 ^Periodic Acid Solution B. Dissolve 400 mg. periodic acid in 45 ml. 

 distilled water and add 5 ml. ilf/5 sodium acetate. 



lodide-Thiosidfate Solution. Dissolve 1 g. potassium iodide and 



1 g. sodium thiosulfate (Na2S203.5H20) in 20 ml. distilled water 

 and add with stirring 30 ml. alcohol followed by 0.5 ml. 2 N 

 hydrochloric acid. A sulfur precipitate forms and settles out 

 slowly although the soln. may be used immediately. 



Feulgen Reagent. See page 67. 



Sulfite Wash Solution. Add 0.5 ml. cone, hydrochloric acid and 



2 ml. 10% potassium metabisulfite to 50 ml. distilled water. 



PROCEDURE 



1. If water-soluble polysaccharides are to be stained, fix the 

 tissue in a dehydrating soln. such as Carnoy fluid (page 45), 

 Otherwise, use any of the usual fixatives. After fixation remove 

 traces of mercury, if present, with iodine and be sure any formalde- 

 hyde is completely removed by washing. (70% alcohol may be used 

 as a washing soln. if it is desired to avoid removal of water-soluble 

 polysaccharides.) 



2. Place section or smear in the periodic acid soln. A or B 

 (depending on whether an alcoholic or aqueous soln. is desired) 

 for 5 min. 



3. Flood with 70% alcohol (or water) and transfer to the iodide- 

 thiosulfate soln. for 5 min. 



4. Again wash with 70% alcohol (or water) and then transfer 

 to the Feulgen reagent for 15-45 min. 



5. Rinse with the sulfite wash soln., dehydrate, and mount as 

 usual. ^ 



^ Result. Polysaccharides are indicated by the violet fuchsin color. 



note: If free tissue aldehydes are present it is necessary to remove them 

 first as on page 93. 



