Abstract
A pathogenic strain of Staphylococcus aureus grown in the presence of a high concentration of lactose, mannitol and gelatin produces a great deal of soluble coagulase and a comparatively small amount of gelatinase. Owing to the nature of the growth conditions, the soluble coagulase may be prevented from diffusing into the medium. This results in the formation of a capsulelike structure which has been termed "pseudocapsule." Presence of soluble coagulase about the cells in vivo might offer some protection to the staphylococci against the humoral and cellular defenses of the host.