EN
The effect of hexachlorethane, 1, 4, 2, 3-chlormethylbenzene and hexachlorophene, given in therapeutic doses, on the vitamin B₂, B₁₂ and PP levels in the caecum content and liver of rats as well as on the serum vitamin B₁₂ level was studied. Histological and histochemical changes in internal organs of rats receiving the same compounds were also examined. Hexachlorethane produced significant changes in the level of vitamins B₂ and B₁₂. These changes were observed chiefly in the first stage of experiment. The remaining compounds, i. e., 1, 4, 2, 3-chloromethylbenzene and hexachlorophene inhibited slightly the synthesis of vitamins B₂ and B₁₂ in the caecum during the first 12 or 24 hours after application but, in general, they had no practical effect on the level of vitamins B₂, B₁₂ and PP in rats.