Organic Substances 73 



chondroitinsuKate.'^^ While both the mucinoids and amyloid 

 will stain metachromatically with all tlie dyes enumer- 

 ated,^^' '^^ the metachromasia of mucinoids with methyl yiolet 

 is very much less marked than with the thiazin and oxazin 

 dyes, and the opposite holds for amyloid. This fact shows 

 that the phenomenon of metachromasia is more complex 

 than it would appear from the relatively simple theory of 

 Michaelis and Granick.^^ 



The results of metachromatic staining of mucin vary 

 greatly with the tissue, fixation, and other incalculable details 

 of technique. Actually, these random and uncontrollable vari- 

 ations appear to be more important than the quaUty of the 

 dye used or the special method followed. Of course, it can- 

 not be denied that a certain batch of dye may give unusually 

 good or unusually bad results, or that one of the specific 

 techniques may yield better pictures than other methods in 

 a given case. However, there is no single method which can 

 be depended upon to give optimal results with all types of 

 material. In our hands, satisfactory results were usually ob- 

 tained with pinacyanol, introduced by Sylven,"^* with toluidin 

 blue and with celestin blue."^^ For the metachromatic stain- 

 ing of mucin, the use of almost any type of fixative, with the 

 exception of bichromate-containing mixtures, is permissible. 



Methods 



a ) Toluidin blue or pinacyanol.— Use a dilute ( about 0.02- 

 0.05 per cent ) solution of either pinacyanol in distilled water 

 or toluidin blue in a citrate buffer of pH 3.5-4.5. Stain section 

 for 10-15 minutes or until, on inspection under the micro- 



71. Hass, G.: Arch. Path, 34:92, 1942. 



72. Johansson, G. A, and Wahlgren, F.: Acta path, et microbiol. Scandi- 

 nav., 15:358, 1938. 



73. Bignardi, C., and Casella, C.: Boll. Soc. med.-chir. Pavia, 55:843, 

 1941. 



74. Sylven, B.: Personal communication. 



75. Lendrum, A. C.: In Recent advances in clinical pathology (London: 

 J. & A. Chm-chiU, 1947), p. 457. 



