Abstract
Three methods at present available for the purification of staphylococcal delta-haemolysin were compared as to the purity and identify of the product obtained. None yielded a pure preparation of delta-haemolysin; one of the three preparations did not contain demonstrable delta-haemolysin when tested electrophoretically, but it contained deoxyribonuclease, penicillinase, phosphatase and alpha-haemolysin. The second preparation had delta-haemolysin activity and was free of alpha-haemolysin, but it contained lipase, egg-yolk factor, esterase, deoxyribonuclease, penicillinase, phosphatase and hyaluronidase. The third preparation contained all of the products mentioned above, except phosphatase, and it also contained alpha-haemolysin, staphylokinase, lysozyme and caseinase. These findings are discussed with special reference to the requirement for criteria of purity in work with staphylococcal products.