“…Ditranol, a common lopical antipsoriatic drug, as also acridines, is pro posed to act thus, probably by intercalation (13,24,27). An induction of respiration-deficient mutants of yeast with c. v. in concentrations of I 0 ' -10-• g/ml has recently been shown (23). This type of mutation is caused by interaction with the mitochondrial DNA.…”