In countries where vaccination against swine erysipelas has been practiced during the last half century, there is a consensus among veterinarians that the best results are obtained when the live culture-vaccine is not only fresh and highly virulent but is endowed also with a good capacity for growth on artificial culture media. Apparently avirulent culture-vaccines are apt to engender only a transitory immunity or fail altogether. The problem presented by undesirable culture-vaccines was deemed to be of such importance to the swine industry that this Station undertook a series of experiments, to determine what influences might be accountable for the production of inferior vaccination materials
