The phenomenon of flicker fusion requires no elaboration to the modern reader. Its psychological, physiological, physical determinants have been outlined by an immense literature (1). Even the limited field of the effects of chemical agents on flicker and fusion is great. In a recent review Landis (2) went so far as to suggest that CFF might be employed as a method of standardizing the depressant effects of somnifacient drugs (Landis (2)). Despite contradictions, which may occur due to the biphasic characters of certain drug effects, the barbiturates and similar depressant compounds tend to depress CFF whereas the stimulants tend to raise it. The effects of alcohol and caffeine are still unclear (Simonson and Brozeck (3)). Whether the drugs affect the organism towards greater or lesser total sensitivity or whether the changes are due to some complex function of, say, the light/dark ratio is also unclear.