The joints of rabbits are predilection sites of disease in chronic avian infections and are nearly always found affected in rabbits which have lived longer than 3–4 months after an intravenous or subcutaneous inoculation of fully virulent avian strains. Highly attenuated avian strains, namely, those which have ceased to be infective for fowls, also give rise to joint disease in rabbits when injected intravenously; for example, twelve rabbits which lived over 5 months after intravenous inoculation of 2·5–10·0 mg. of attenuated avian strains all showed joint tuberculosis, and in eleven of these the joints were the only affected parts (Griffith, 1925).