1. The enzyme present in the pneumonic lung exudate still remains active after preservation for 18 months.
2. The enzyme is active at incubator temperature before and after heating to 65°C. for 1 hour. It is slightly active at room temperature and inactive after heating at 75°C. for 1 hour.
3. Dialysis of the enzyme is not demonstrable.
4. Activity persists when the enzyme is mixed with concentrations of sodium chloride varying from normal to thirty-two times normal.