Abstract
Since coagulase-positive staphylococci from animals are heterogeneous, another test is necessary to distinguish Staphylococcus aureus from them. Staphylococcal thermonucleases appear to be heterogeneous; antisera raised against S. aureus isolated from humans inhibit thermonuclease activity as demonstrated by the metachromatic well-agar diffusion method. The serological specificity of the thermonuclease elaborated by S. aureus of human origin was demonstrated using three antisera and 407 strains of staphylococci from diverse human and animal sources.