1. A method is presented for the quantitative comparison under various conditions of the activity of the lipolytic enzyme of the hemolytic steptococcus. The speed of acid production as shown in the color change from pH 8.0 to 7.2, when the living streptococcus is suspended in association with ethyl butyrate, is considered to be indicative of the amount of ferment elaborated by the organism.
2. The lipolytic action is a function of living, actively growing organisms such as are present in 4 to 8 hour cultures.
3. The speed of the lipolytic action is approximately in linear proportion to the concentration of the organisms.
4. The lipolytic action is most rapid at 37.5°C., slower at 50°, and absent at 62°.
5. The organisms are partially destroyed and the lipolytic action is markedly delayed by previous heating to 55°C. for 10 minutes. Both the organisms and the lipolytic activity are completely destroyed by continued contact with this temperature for 30 minutes.
6. Increasing the virulence of the organism for rabbits by repeated animal passage does not increase the lipolytic action.
7. The predilection of the hemolytic streptococcus for the subcutaneous fat in local streptococcus infection associated with extensive superficial gangrene cannot be explained on the basis of an increase of lipolytic ferment in the organisms recovered from these cases over that of heterologous strains of streptococci.