Abstract
1. There is no denying the fact that many organisms identified biologically as Erysipelothrix rhusiopathiae are isolated in a high rate from the body surfaces of dead marine fish through mouse inoculation, while none are isolated from live fish. 2. The organisms isolated from the body surfaces of dead fish must have multiplied after the fish were caught and had come into contact with surrounding articles which were contaminated with various organisms. 3. Most of the fish strains of Erysipelothrix rhusiopathiae showed, serologically, different behaviours from the pathogenic groups (Groups A and B) of swine erysipelas. Accordingly, they have scarcely any epizootiological significance in relation to swine erysipelas. 4. A discussion was made, in relation to the above mentioned results, on the high isolation rate of Group B organisms obtained from the tonsils of apparently healthy pigs.
