Majovski''s method for assay of vit. P effects on capillary permeability was subjected to a critical test. White mice were exposed to a vacuum of 85 mm. Hg for 10 secs. Fed mice showed hemorrhages in the lungs, while fed mice injected up to 45 mins. before the test with rutin did not show any or only a few pulmonary hemorrhages. In control tests with the solvents used for the rutin and with other substances, it was found that the "protection" given to animals by rutin was not specific, since mice were protected as well by propylene glycol, ethylene glycol, ethyl alcohol, and glucose.