The debated question as to whether allergic and anaphylactic manifestations in experimental tuberculosis are basically similar or different has been reinvestigated by Corper.1 His results strongly support the view that the phenomena are of fundamentally different nature. Significant facts partly here reported and partly cited seem to establish the following facts: Guinea pigs which receive intravenous injections of protein from tubercle bacilli are sensitized so that typical anaphylactic shock is caused by later injection of this protein. The sensitization can be transferred passively to normal guinea pigs with the blood. However, guinea pigs rendered "allergic" by infection with a strain of tubercle bacilli of low virulence do not demonstrate the characteristic anaphylactic type of hypersensitiveness when injected with the tuberculoprotein. In appropriate amounts the latter will kill such pigs, but only after several hours, a type of death in clear contrast to the rapidly occurring death of anaphylaxis.