Abstract
Mice treated with an antigen prepared from livers infected with Bacillus piliformis developed antibodies to the microorganism which reached a peak on the 7th day and disappeared within 40 days: antibody titres in experimentally-infected mice remained at a high level throughout life. The antibody titres in naturally-infected mice, rats and rabbits remained positive throughout life and followed the same pattern as that of the experimentally-infected mice.