STUDIES ON NATURAL IMMUNITY TO PNEUMOCOCCUS TYPE III : I. THE CAPACITY OF STRAINS OF PNEUMOCOCCUS TYPE III TO GROW AT 41°C. AND THEIR VIRULENCE FOR RABBITS

1. A correlation appears to exist between the failure of certain strains of Pneumococcus Type III to grow at 41°C. and their lack of virulence for rabbits.

2. It is likely that the capacity to grow at 41°C.—an attribute constantly but not exclusively associated with strains of Pneumococcus Type III virulent for rabbits—is a prerequisite, but not the sole factor, in determining their virulence for these animals.