1. Though in general in pneumococcus pneumonia the appearance of protective substance coincides rather sharply with the fall in the temperature, antibody may appear spontaneously in the blood serum as early as the 3rd or 4th day and crisis and recovery may be delayed until the 6th to the 10th day.
2. Recovery at times occurs without demonstrable protective substance in the blood in patients who later develop protection.
3. The amount of antibody developed in the course of pneumococcus pneumonia is small and in the majority of cases tested was insufficient to protect against more than 100 lethal doses of homologous pneurnococci and never against more than 10,000 lethal doses.
4. Treatment with Felton's antibody late in the course of the disease materially increases the amount of protective substances in the blood. A high degree of protection may be established by treatment in fatal cases. After the 3rd day doses of more than 200,000 Felton units are usually necessary to produce a greater degree of protection than might otherwise be expected.
5. The formation of protective substances by the patient himself is not an assurance against progress of the infection to a fatal termination.
6. Protective substance in the blood and pneumococcic septicemia may occur simultaneously.