AN ARTICLE by Davis1 on the differential diagnosis of paralysis of a superior oblique muscle and paralysis of the opposite superior rectus muscle has revived the argument between Bielschowsky and Duane as to the relative frequency of these paralyses, the former believing that most vertical anomalies are due to paralysis of the superior oblique, while the latter credited the superior rectus with the majority. Davis found the superior oblique paretic in 54.5 per cent of 88 cases of vertical anomalies and the superior rectus in 45.4 per cent. White and Brown2 had previously reported that only 4 per cent of cases of vertical anomalies were due to paralysis of the superior oblique and that 96 per cent were due to paralysis of the superior rectus. Smith3 recently pointed out the serious discrepancy between these two sets of figures and pleaded for a more uniform standardization of methods