1. In guinea-pigs a sufficient degree of infection with the organism of
tuberculosis can be set up by artificial means so that reactions with tuberculin
are given within from 24 to 30 days. This means that the period of 6-8 weeks
usually elapsing before subjects injected with suspected tuberculin material
are killed for diagnosis can be shortened by testing the subject and a control,
with tuberculin in from 24 to 30 days, thus expediting results of tests.
2. Animals infected with Br. abortus may give strongly suspicious
reactions when tested with tuberculin.
3. Reactions strongly suspicious of positive tuberculin reactions have
been observed in cattle that were pregnant and' close to the time of parturition.
A similar case was observed in a control guinea-pig.
4. Guinea-pigs infected with strains of non-pathogenic acid-fast
organisms gave reactions in some cases when tested with tuberculin in a
dilution of 1 to 100. More marked reactions to tuberculin were obtained
when lower dilutions were used, viz., 1 to 10 to 1 to 40 dilutions.
5. Extracts prepared from non-pathogenic acid-fast organisms, in the
same way as tuberculin is prepared, appear to contain some antigenic factor
common to all members of this , group that gives rise to reactions
when inoculated into small animals artificially infected with separate
members of this group.
6. Extracts prepared on the lines of L'anaexo-Tuberculin may contain
products that are specific for each member of the acid-fast group of organisms.
7. Cattle up to 2½ years of age can be sensitized by the subcutaneous
inoculation of 10 mg. of strains of M. butyricum and M. phlei suspended in
liquid paraffin. Larger amounts of the organisms do not appear to give rise
to a greater degree of sensitivity.
8. Cattle sensitized by subcutaneous inoculation of strains of M. butyricum
and M. phlei gave definite suspicious reactions when tested with
tuberculin by the double intradermal method.
9. These same animals when tested with avian tuberculin showed no
more marked suspicious reactions than when tested with standard tuberculin.
10. Thirteen and a half months after subcutaneous inoculation with
strains of M. butyricum the non-pathogenic organism M. butyricum could
be cultivated from pus obtained from the resultant lesion.
11. Sections cut from the lesions set up by these two organisms showed changes indistinguishable from those set up by tuberculosis.
12. Four months after the surgical removal of the lesions set up by the
inoculation of the non-pathogenic acid-fast organisms the animals still gave
definite positive reactions when tested against the corresponding extracts.
13. It is probable that some non-specific reactions shown by animals,
when tested with tuberculin, may be due to these animals being sensitized
naturally by a strain or strains of some non-pathogenic acid-fast organism.
14. This may also be an explanation for some of the "no lesion"
reactors to the double intradermal tuberculin test.