Extracts containing acid hydrolases and lysozyme derived from human and rabbit blood leukocytes, from rabbit peritoneal and lung macrophages and from peritoneal PMN are highly lytic for relabeled Staphylococcus albus, Streptococcus faecalis, and Streptococcus mutans. On the other hand, extracts of human and rabbit platelets and of rabbit lymphocytes, thymocytes, synovia and muscle are not lytic for these bacteria. A phenomenon is described in which lysozyme which is not lytic to these bacteria collaborates with nonlytic extracts of lymphocytes platelets, thymocytes, synovia and muscle in the lysis of Gram positive bacteria. Lysozyme also enhances the lysis of bacteria by extracts of PMN and macrophages. It is postulated that the bacteriolytic system present in PMN and macrophages comprises a group of preparatory nonlytic enzymes, also present in lymphocytes, thymocytes, platelets, and other tissues that prepare the peptidoglycan to cleavage by lysozyme. The preparatory enzyme systems of leukocytes and tissues have a pH optimum of 5.0 and are strongly inhibited by heparin and chondroitin sulfate. The relationship of the synergism between lysozyme and tissue enzymes in the degradation of microbial cells is discussed in relation to the pathogenesis of granulomatous inflammation.