Whereas the injections of trypsin in the peritoneum of the rat cause every time a polyseritis (ascites and pleuritis) the trypsin inactivated by di-iso-propyl-fluoro-phosphate remains without effect; this fact proves therefore that the proteasic properties of the trypsin are responsible of this exsudative effect on peritoneum and pleura. 2. The intra-peritoneal injections of elastase cause also a polyseritis in the rat, but it is complicated by shock. 3. The dosage of the proteasic activity in the effusions caused by the trypsin and the elastase, shows a progressive reduction of this activity. At the beginning there is more protease in the ascites than in pleural serositis and the volume of the ascites is greater; later, the findings about the proteases are opposite and the protease content becomes greater in the pleural effusion. This evolution is a new proof of the transdiaphragmatic propagation of the proteasic polyseritis.
