[On the birefringence of formazans (author's transl)]

The enzyme succinate dehydrogenase was demonstrated histochemically in organs of rats, especially in experimentally infarcted hearts. 88 tetrazolium salts were used as indicators, the resulting formazans were examined for birefringence. Formazans with cristalline shapes show birefringence, but formazans of amorphous character do not. In the atypic species of nitrogroup-substituted monoformazans it is possible to form an oriented association to cell structures in spite of an amorphous precipitation. Therefore, anomalous colours of polarization, and dichroism is observed. Relations are discussed between shape of formazan deposits, polarity of formazans, and the occurrence of optical anisotropism.