The proteases, amylase and lipase of the pancreas and intestinal contents of germ-free and conventional rats

I . Measurements were made of the proteases, amylase and lipase of the pancreas and of the corresponding intestinal, caecal and colonic contents of germ-free and conventional rats. 2. Little difference was found between the concentration of the enzymes in the germ-free and conventional rats. 3. The results indicate that intestinal bacteria had only a minor part in determining the fate of the pancreatic enzymes in the contents of the intestine, caecum and colon. 4. The enzyme concentrations decreased caudally. The proteases were the most stable, and the amylase was the least stable; the stability of lipase was intermediate between that of the proteases and amylase. 5 . Evidence of bacterial activity in the caecal contents of conventional rats was seen in the greater percentage of protein nitrogen and in the lower percentage of the non-protein nitrogen.