[Problem in the determination of calcinosis by means of hematoxylin]

The histochemical analysis of a number of dystrophic and metastatic calcifications revealed that the haematoxylinophilia of calcified tissues is not based on the inorganic component, but on their organic component. In most of the cases the material examined contained protein on the basis of its staining properties, as well as neutral and acid mucosubstances and, most probably, also covalently bound phosphate. Exceptionally the organic component appeared to be unequivocally acidic phospholipid, tigtly bound to an inorganic component. The significance of the findings has been discussed.