“…The second is a histochemical technique in which mercury is detectable by colored precipitates in metal chelating mechanism using diphenylthiocarbazide (Brandino 1927, Okamoto, Seno andOkumura 1944), dithizone (Okamoto, Seno and Okumura 1944) and rhodizonate (Feigl and Suter 1942). The third is to make metal precipitates detectable by use of stannous chloride (Christeller & Sammartino 1928, Kuroda 1951. The fourth is a silver impregnation technique (Timm 1958, Voigt 1958, Shiraishi 1964, Silberberg et al 1969.…”