Formation of protein in the pancreas.

1. The total known secretory enzyme content of the mouse pancreas has been determined and found to represent about 20 per cent of the weight of the dry, fat-free tissue. 2. The changes in secretory enzyme content that occur during the cycle of secretion and synthesis have been measured. 3. In the course of the cycle no significant changes have been found in DNA or RNA content of pancreatic tissue. 4. Constancy of DNA content, along with other observations, indicates that total protein content of the gland remains substantially unchanged during the cycle of secretion and synthesis. These facts point to the conclusion that following upon the secretion of enzyme protein, synthesis of new protein takes place relatively rapidly in the exocrine cells of the pancreas and this protein is then gradually transformed into the characteristic pancreatic enzyme proteins.