The determination of the phospholipase content of pancreases from all species was performed in a homogenate prepared in a Waring Blendor (2 × 30 s) with 10 ml, per gram of fresh tissue, of 10 mM Tris-HCl, 150 mM NaCl, and pH 8.5 at room temperature. After centrifugation at 12.000 rpm during 20 min, the amount of enzyme was estimated on an aliquot of the supernatant using PC emulsion as substrate in the presence of 4 mM NaTDC and 8 mM CaCl2. The phospholipase activity was measured titrimetrically at pH 8.0 and at 37°C using a pH-stat. One phospholipase unit corresponds to one μmole of fatty acid released per min using PC emulsion as substrate in the presence of 4 mM NaTDC and 8 mM CaCl2. For each species, the activity represents the average ± standard error mean of five assays obtained from three different pancreases.