Organic Substances 75 



scribed here mainly because it is useful for the demonstra- 

 tion of some types of mucin. 



Method 



Prepare a colloidal solution of ferric hydroxide by the 

 method of Rinehart and Abul-Haj.^*^ Dissolve 30 g, of ferric 

 chloride (lumps) in 100 ml. of distilled water, add 40 ml. of 

 glycerol and, in small portions and under continuous stirring, 

 22 ml. of concentrated ammonia water. Dialyze the mixture 

 under the tap for about 48 hours ( caution: fill the dialyzing 

 bag less than halfway because there will be about a 2.5-fold 

 increase in volume). Filter the dialyzate; it will keep indefi- 

 nitely. For use, mix about 10 parts of the dialyzate and 1 

 part of concentrated acetic acid. This mixture is stable for 2 

 days only. Stain slides in the mixture for about 10 minutes, 

 rinse them in repeated changes of distilled water, and im- 

 merse for 10 minutes in a fresh solution containing about 1 

 per cent each of hydrochloric acid and potassium ferrocya- 

 nide. Counterstain with a red nuclear dye, dehydrate, and 

 mount. 



The mannitol-FeCls method of Lillie and Mowry*^^ gives 

 results almost identical with those of Hale's technique. 



Ritter and Oleson"^^ suggest the McManus stain as a coun- 

 terstain. Some substances will appear in a blue, others in a 

 red shade; the interpretation of this difference is not clear. 



c) Heparin (granules of mast cells) .—Holmgren and Wi- 

 lander"^^ suggest primary fixation in a 4 per cent solution of 

 basic lead acetate for 12-24 hours; this may be followed, for 

 better cytological detail, by formalin. Lead acetate precipi- 

 tates heparin in the form oiF an insoluble lead salt. After this 



76. Rinehart, J. F., and Abul-Haj, S. K.: Arch. Path., 52:189, 1951. 



77. Lillie, R. D., and Mowry, R. W.: Bull. Intemat. A. M. Mus., 30:91, 

 1949. 



78. Ritter, H. B., and Oleson, J. J.: Am. J. Path., 26:639, 1950. 



79. Holmgren, H., and Wilander, O.: Ztschr. f. mikr.-anat. Forsch., 

 42:242, 1937; Holmgren, H.: Ztschr. f. wissensch. Mikr., 55:419, 1938; 

 Holmgren, H.: Ztschr. f. mikr.-anat. Forsch., 47:489, 1940. 



