On account of its weaker reactions for tryptophan, tyrosine, proteolipids, and lipoproteins, sarcoidotic-hyaline (Sa. Hy.) is immediately distinguishable from caseosis. However, protein histochemistry fails to differentiate Sa. Hy. from normal (fixed and insoluble postfixed) and pericaseous collagen. Evidence of this is provided by the present study on carbohydrate histochemistry. Sa. Hy. differs from both normal collagen and pericaseous dense connective tissue in that S-mucopolysaccharide A (0.7 MgCl2) is absent, while C-mucopolysaccharide is present. Moreover, Sa. Hy. contains U-mucopolysaccharide and traces of S-mucopolysaccharide B 4.0 T which are not detectable in caseosis. Interesting collateral findings are the histochemical tests for copper and ferric iron, which are both positive in Sa. Hy. The former is only weakly positive in the collagen of both types; the latter is negative in the remaining structures studied. Pericaseous dense connective tissue does not differ, histochemically, from normal collagen, while Sa. Hy. presents a well-established histochemical pattern suggesting the appearance of a modified connective tissue.