Abstract
1) A method is proposed for the demonstrations of dehydrogenases and diaphorases using the principle of simultaneous chelation of an enzymically produced monoformazan by means of metallic ions.
2) Using 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyl tetrazolium and M/60 cobalt a black metal-formazan complex is produced. Its nature is such that fine intracellular localisation becomes possible.
3) Chelation occurs under histochemical conditions with cobalt, copper, nickel and uranium and it is suggested that the electron opacity so induced may facilitate localisations of dehydrogenases on the electron microscope level.