Thesis (Ph.D.)--Boston University / The purpose of this investigation was to concentrate, purify, and assay the enzyme elaborated by certain strains of Micrococcus pyogenes var.aureus (Staphylococcus aureus), whereby these organisms are capable of effecting the lysis of fibrin. These studies included the selection of strains capable of producing filtrates containing potent kinase; the selection of a culture medium which woud support the growth of the organism, and at the same time insure adequate enzyme production; a method of concentration and assay of enzyme activity; and studies of the concentrate for properties characteristic of various pathogenic staphylococci. A review of the literature pertaining to staphylokinase or as it had formerly been designated, staphylococcal fibrinolysin, is presented. Few data are available for the production of staphylokinase specifically; however, it has been generally agreed that coagulase activity, hemolysin and pigment production, as well as kinas activity, are intimately related to the pathogenicity of the organism. Therefore, strains used in these studies of kinase production were selected primarily on the basis of these other criteria. [TRUNCATED]