336
ABSTRACTS
In the first experiment which was of a preliminary nature, four pairs of calves were
used, the animals being fed morning and evening. Two pairs received 14 daily doses of
ordinary raw milk, which constantly contained small numbers of tubercle bacilli sufficient
to infect guinea-pigs, though not usually demonstrable in smears of centrifuged deposit.
The other calves received three doses of half-a-pint of heavily contaminated milk ob-
tained by mixing several samples from cows with tuberculous mastitis. This milk
infected guinea-pigs in a dilution of 1 : 100,000 and tubercle bacilli were readily
demonstrable in smears of the deposit. It was diluted 1 : 4 with pasteurized milk before
being fed to the calves, whilst the ordinary raw milk was fed undiluted.
In each group of 4 animals one pair drank the contaminated milk out of an ordinary
bucket, while the other pair was given it by stomach tube passed into the rumen. Dur-
ing withdrawal of the tube pasteurized milk was run through so as to minimize-the risk
of carrying infected milk into the throat. The total amount of slightly contaminated
milk given to each calf was about 30 pints, while the amount of the highly contaminated
milk received by each of the four calves was 1½ pints. It is calculated that the total
number of bacilli given to the two series of calves were in a ratio of about 1 : 5,000.
Of the four calves given ordinary raw milk two failed to develop tuberculosis, viz.
one which received the contaminated milk by tube and the other by bucket. The other
two showed at autopsy primary lung tuberculosis of the aspiration type with caseous
bronchial nodes and involvement of the anterior mediastinal nodes. One of these had
regurgitated and aspirated some of the contaminated milk and recovered only after several
days' severe respiratory distress.
Of the four given highly contaminated milk, one was killed in extremis 27 days after
the last feed and on autopsy showed an acute focal interstitial nephritis and no tuber-
culosis. Of the other three, which all proved infected, one showed primary tuberculosis
of the tonsil and intestine, the second primary tuberculosis of the .ung and bronchial
node with a second primary lesion in the right suprapharyngeal node, while the third
which had regurgitated showed primary tuberculosis of the lung and bronchial node
besides a calcified lesion in a mesenteric node. The tonsil and suprapharyngeal node
of this animal were positive on guinea-pig inoculation.
Further experiments were carried out in which an attempt was made to introduce
a culture of bovine tubercle bacilli about 4 weeks old directly into the duodenum under
general anaesthesia. The anaesthetic first tried was nembutal intravenously but this
proved unsatisfactory and two calves were lost. Later pentothal sodium was substituted
and this proved satisfactory, as it gave a period of anaesthesia lasting some 20 minutes,
which was long enough for such operational interference as was required. In the first
trials the culture was injected into the duodenum by means of a syringe, but as this
resulted in the formation of a tuberculous nodule in the wall of the duodenum, in later ex-
periments the culture was enclosed in a gelatin capsule, which was sealed by immersing in
collodion. The capsule was introduced into the duodenum by means of an ejector inserted
into it through an incision made in the abdominal wall. Two calves were given in this
way 0.01 and 1.0 mg. of culture respectively. The first showed no lesions of tubercu-
losis when killed 36 days later, while the second which was killed 17 days after operation
showed at autopsy tuberculosis of the abomasal wound and of the regional lymph node,
the capsule having come apart in the abomasum during insertion. Histological examina-
tion showed small foci of epithelioid cells in the hepatic and 2 mesenteric lymph nodes.
A series of 6 calves was then given varying doses of tubercle bacilli in double gelatin
capsules, a small capsule containing the culture being enclosed immediately within a
larger capsule and the latter sealed by dipping several times in collodion.
Two calves received 1.0 mg. of culture. One of these died 36 hours after the opera-
tion from an acute streptococcal infection. The other killed 58 days after the operation
showed extensive tuberculosis of Peyer's patches throughout the small intestine. Lesions
were also present in the mediastinal, hepatic and bronchial nodes and there was generali-
zation involving the lungs and spleen. In this calf the abomasal wound also showed tuber-
culous foci, the gelatin capsule having come apart during insertion.
Two calves received 10.0 mg., but in both these animals the capsule had probably
been accidentally liberated from the ejector in the abomasum. One was killed 36 days
after operation and at autopsy showed lesions in all the mesenteric nodes and Peyer's
patches. The other was found dead 14 days after operation. There was no microscopic