12 BULLETIN 517, U. S. DEPARTMENT OF AGEICULTUEE. 
COMPARISON OF RESULTS OF AGGLUTINATION AND INTRA- 
DERMAL TESTS ON NATURALLY INFECTED BIRDS. 
Through the assistance of Eoy E. Jones, we located and purchased 
47 birds that had given positive or questionable agglutination tests, 
applied by the Connecticut Agricultural Experiment Station. These, 
together with nine controls, were injected for the intradermal test 
on June 23, 1916, and readings were taken at 24 and 48 hours. 
Of the birds reported positive to the agglutination test applied by 
the Connecticut station, there was total agreement in 28, or TO per 
cent, of the cases in that they also gave positive intradermal test as 
determined 24 hours after injection and displayed unquestionable 
lesions when eventually slaughtered. Of those reported positive to 
the agglutination test, 30, or 75 per cent, revealed lesions at autopsy. 
Thirty-five birds gave positive reactions to the intradermal test. 
Autopsy revealed that of these 29, or 83 per cent, possessed un- 
doubted lesions, in 5 the lesions were questionable, and in 1 no lesions 
occurred. Of those reported positive to the agglutination test, 3 
birds, or 7 per cent, failed to react to the intradermal test, and 
autopsy revealed no lesions. On the other hand, 2 birds, or 5 per 
cent, that had given positive agglutination tests, gave negative in- 
tradermal tests, and autopsj^ revealed lesions. Thus, the percentage 
of absolute failures of each test as judged by the other test and by 
the autopsy findings were very similar in amount. 
Seven birds had given questionable agglutination tests. Of these, 
3 were negative to the intradermal test and negative at autopsy. 
One reported questionable gave a positive intradermal reaction and 
autopsy revealed lesions. The intradermal test on the other 3 yielded 
positive, negative, and questionable results, respectively, and autopsy 
of all 3 furnished inconclusive information. 
Of the nine controls, one displayed a marked reaction at 24 hours, 
consisting of a swelling of the wattle to three times its normal thick- 
ness. Autopsy revealed undoubted lesions, and a pure culture of 
Bacterium pullorum was isolated from the ovar}^ Four others dis- 
played traces consisting of swelling of the lower border of the wattle 
to about twice the normal thickness. On autopsy, one of these was 
found to contain undoubted lesions and a pure culture of B. pullorum 
was obtained. 
The examination of the wattles at 48 hours revealed swellings vary- 
ing from a trace to positive in only 22 birds, or 46 per cent, of those 
tested. This result compared with the 28 birds regarded as positive 
at 24 hours and verified by subsequent autopsy, again indicates that 
48 hours is too long to secure all the positive reactions. Among the 
controls only 1 displaj^ed any swelling whatsoever, and this case 
proved on autopsy to be positive. 
