Under controlled conditions of maintenance and treatment of test cats, and with inducement of decisive vomiting as the criterion of enterotoxicity, the "Dolman kitten-test" has provided a high degree of positivity for the detection of an emetic principle in preparations from staphylococcal cultures. These conclusions are based on 315 individual cat injections. Under the conditions of these experiments and with the use of 133 control preparations, false positive reactions likely to cause confusion in normal determinative tests were not encountered.

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A substance present in culture filtrates of enterotoxigenic staphylococci that is distinct from alpha-, beta-, or delta-lysins causes vomiting; in cats when injected by the intraperitoneal route. An emetic fraction containing only vestigial traces of lysins can be resolved into three protein components and one polysaccharide by use of the Durrum ionophoresis method. The only component of this group that gave indications of enterotoxicity was a protein with specific mobility, relative to the others. Hemolytic proteins were separated by paper ionophoresis using the method of McKinley, Maw, Oliver, and Common.

The reported study of the l;no~vn toxins of six different strains of enterotoxigenic staphylococci of diverse lysin productivity allows the conclusion that the enterotoxin, as indicated by the emetic response of cats, is a specific entity that is distinct from or-, p-, or 6-lysins. Emesis in cats may also be caused by p-lysin if injected in quantities greater than SO units per ligm. The Dolman Ititten test for enterotoxin may be made less eq~~ivocal by selective removal of all traces of lysins by boiling of the test specimen followed by incubation in the presence of ascorbic acid. Lysins inactivated by heat, formalin, homologous antitoxins, or ascorbic acid do not cause emesis. Immunization of cats with specific enterotoxic filtrates has demonstrated the existence of antigenically distinct enterotosins. a t 57" C. than a t temperatures above 80" C.On the other hancl, North (15) has shown t h a t a number of strains t h a t produced alpha-lysin were not enterotoxigenic, while Dolinan (3) was able t o inhibit the production of alpha-lysin by incubating cultures a t room temperature without curtailing the enterotoxicity of a filtrate. Dolman and Wilson &Ianz~script received Janz~ary 26, 1955. A contrihz~tion from the laboratories of the Food and Drug Directorate Department of National Healtlt attd Welfare, Ottawa, Canada. Can. J. Microbiol. Downloaded from www.nrcresearchpress.com by McMaster University on 11/26/14 For personal use only.

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