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ABSTRACTS
Double the thickness of the normal skin on the D. I. D. test with 0.1 c.c. of the
synth tic johnin and P. P. D. johnin was the criterion of a positive reaction. The
P. P. D. johnin was a slightly better diagnostic agent than synthetic johnin which
was superior in potency and specificity to avain tuberculin. Goats infected with
intestinal scrapings or with cultures developed allergy very slowly. The lag phase
in the development of allergy varied between about one to six months and is com-
parable to that of cattle. The allergy waned in advanced cases but in those which
developed progressive disease the allergy remained for a long time. Although a
positive reaction was more significant a negative reaction did not mean that the
animal was not harbouring the organisms or shedding out the bacilli in faeces.
Artificially infected young goats can replace cattle for testing of johnin prior to their
use in the field.
Antiformin 10 and 20 per cent was usually used for the isolation of cultures from
the faeces. Dunkin's medium was used and Gentian Violet (1:10,000) was incor-
porated into the medium whenever intestinal materials were cultured. When
administering per os large doses of the organisms were necessary to establish infection.
The bacilli could be found in faeces during the incubation period and long before
the onset of symptoms. A correlation between the results of the johnin test and the
presence of the bacilli in the faeces was found and the balance on the whole was in
favour of the allergic test.
In early cases the naked-eyes lesions of the intestines were difficult to detect.
In mesenteric glands in clinical cases oedema and sometimes enlargement with the
thickening of the capsule and degeneration with caseous or calcified foci arranged
peripherally presenting a bosselated surface were found.
Histologically the intestinal lesions were similar to those seen in cattle. In the
mesenteric nodes islets of epitheloids and giant cells were seen which showed a
tendency to localise in the lymphatic sinuses and progressively formed syncytial
masses while in advanced cases the normal glandular structure got obliterated.
Caseation and calcified degeneration of the epitheloid cells was also sometimes
observed. Johne's bacilli were found in smears and sections of nodules. Caseation
and calcification were not found in the tonsils submaxillary and pharyngeal lymph
glands, though specific histological changes were found in most of the clinical cases,
the bacilli probably having had a direct entry in the lymphatics of the mouth and the
pharyns. Specific bacilli were also recovered in culture from the bronchial pharyn-
geal portal tonsillar and submaxillary glands in advanced clinical cases but the
bacilli remained confined to the intestines and mesenteric glands in all early cases.
The liver and bile were also found to be infected on culture. One infected goat
which showed avain tubercle bacilli in the mesenteric gland revealed johne's bacilli
in the tonsils and pharyngeal nodes but not in the mesenteric glands and intestines.
The author has discussed in the end, the portal of entry of the bacillus and affirms
that the main entrance is through the intestinal wall whence the lymphatic glands
are invaded and the spread of infection takes place afterwards possibly through the
blood stream. (P. C. G.)