A close correlation between the intensity of tissue reaction in skeletal muscles and the localization of some enzymes in the bladder of C. bovis was demonstrated by histochemical methods. The most intensive tissue reaction was observed around the portion of bladder surrounding the opening of spiral canal, the tegument and subtegumental cells of which exhibit a high activity of alkaline phosphatase and acid phosphatase. Around this portion of bladder the tissue reaction is very strong, whereas around the remaining portion of the bladder, without any activity of these enzymes, the reaction is weak. The basic type of the reaction around the portion with alkaline and acid phosphatase activity is the formation of a pseudoepithelial rim, in which occur secondary changes leading to histochemical changes inside and around this rim. The cells of the unchanged pseudoepithelial rim contain proteins with tyrosine, tryptophan and cysteine. Among the cells is a large number of reticular fibres. Flat foci localized directly in this rim contain mostly fibrilar structures rich in acid mucosubstances with carboxyl and sulphate groups which are labile to testicular hyaluronidase and neuraminidase. They contain also a small amount of neutral mucosubstances and give negative reactions for tyrosine, tryptophan and cysteine. Fibrilar structure in these foci undergo dystrophic calcification. A conspicuous accumulation of mast cells is visible in the layers under the pseudoepithelial rim and clusters of cells containing lipopigment are present at the periphery of the connective tissue layer.