Complement Levels in Mammals.

Summary 1. A sensitive, reproducible method capable of measuring complement levels in 7 different mammalian species is described. This method is a modification of the technic of Mayer and co-workers (1). 2. In sera of hamster, rat and dog the hemolytic complement activity is about the same as in that of normal humans; in guinea pig serum it is 7 times greater; in rabbit serum it is one-fourth of that in humans and in mice it is one-sixtieth, although readily measurable. 3. The slope of the hemolytic curve for C3H mice differs from that of all other species examined and also varies for individual mice.