It has been found that when a toad is injected subcutaneously (e.g. in the dorsal sac) with tubercle bacilli the micro-organisms disseminate but are stored in the liver mainly, where they multiply slowly without producing visible lesions and can be recovered by culture or injection of guinea-pigs after several years. Bovine tubercle bacilli were recovered in culture from the liver 1, 2 and over 3 years after subcutaneous injection and tubercle bacilli of avian type were still viable after 900 days in the liver.