Since 1968 the authors have collected the tonsils from pigs infected experi一 mentally or naturally with hog cholera. These pathological changes of the tonsils infected hog cholera showed small necrostic areas. The main results obtained are summarized as follows
1.The tonsils of pigs infected with hog cholera remarkably showed small necrostic areas on macroscopical findings, coagulation necrosis of lymph nodule to be caused by infarction on histological examination. The necrostic tonsillaritis were found 95.6 per cent of 68 cases artificially inoculated with the virus of hog cholera, 86.7 per cent of 30 cases infected naturally with hog cholera respectively.
2. The tonsillar necrosis began to appear at the First day or second daf of the initial rise in temperature. The lesions between right and left side oy tonsil showed no remarkable difference.
3. Among macroscopical finding of pigs infected with hog cholera, necrosis in tonsillar tissue and petech in the kidney were chiefly main changes. Accordingly, the observation of tonsil was useful for clinical diagnosis, because the tonsil of pig is easily observed by opening snout
4.The hog cholera-infected pig should differentiate from pigs infected with toxoplasmosis. because both tonsils showed necrostic tonsillaritis. Then they were some differences in that necrostic tonsillari tis of toxoplasmosis were less lesion, a somewhat longer course to'.began apparing necrosis, and easily finding vetegtative toxoplasma.