Histochemical Detection of Barium and Strontium

SMALL amounts of barium and strontium can be detected in the tissues of many insects by means of the extremely sensitive rhodizonate reaction. This reaction was described for microchemical use by Feigl 1 , who has since investigated its limitations 2,3 . In the present histochemical method, tissues are fixed in carefully neutralized 10 per cent formalin in 70 per cent alcohol and immersed for 30–60 min. in a freshly prepared 1 or 2 per cent solution of sodium rhodizonate, in distilled water or in phosphate buffer at p H 7. Excess sodium rhodizonate is afterwards removed by washing in dilute alcohol. Stained tissues can be sectioned in the usual manner and permanent preparations obtained.