jan. 2,19x7 Diagnosis of Tuberculosis by Complement Fixation 
*3 
antigen. It may be possible that future investigation will establish a 
greater accuracy of this test, but the results obtained warrant the state¬ 
ment that the comparative tests with various antigens have proved that 
an antigen prepared from a bacillary emulsion and tuberculin precipitate 
is most suitable for the completement-fixation test. 
Tablk VIII .—Summary of the tests conducted with an antigen prepared from a bacillary 
emulsion and tuberculin precipitate 
Bovine serum. 
Total 
Degree of fixation. 
Percent- 
number. 
H—1—i—H 
+ + + 
+ + 
+ 
db 
- 
age. 
Group 1: 
Serums from animals without 
lesions of tuberculosis and nega¬ 
tive to the tuberculin test. 
320 
3 
2 
10 
13 
X 7 
275 
85-94 
Group 2: 
Serums from animals showing ar¬ 
rested lesions of tuberculosis.... 
207 
21 
28 
39 
48 
19 
52 
77*15 
Group 3: 
Serums from animals with pro¬ 
gressive lesions. 
79 
II ■ 
16 
23 
16 
5 
3 
83-56 
Group 4: 
Serums from animals showing 
generalized, well marked, or 
extensive lesions. 
43 
13 
9 
4 
7 
4 
7 
74 - 42 
Group 5: .... 
Serums from animals showing 
acute or miliary lesions. 
3 i 
9 
4 
4 
10 
I 
3 
87.1 
Total. 
680 
56 
59 
80 
94 
46 
345 
81.63 
As indicated in Table VIII, out of 320 negative serums a total of 
only 275, or 85.9 per cent, proved distinctly negative on the test; whereas 
of 360 positive serums 290, or 80.5 per cent, were positive. Furthermore, 
of the affected animals 81, or 25.8 per cent, gave only slight positive 
reactions, and 80, or 7.6 per cent, were atypical. The grand total of 
81.6 per cent of accurate reactions obtained is by no means sufficient to 
make the test practical for the control of the disease, especially since the 
allergic tests which we have at our command are more reliable. 
No* satisfactory explanation can be given for the failure of reactions in 
known tuberculous infections or for the positive reactions in apparently 
healthy individuals. In regard to this various theories have been 
advanced; but since there is no confirmatory data available for any of 
these, it appears superfluous to discuss them here. The fact, however, 
that there existed a possibility that some of the positive results in the 
negative cases might have been due to a previous tuberculinization of the 
animals can not be overlooked, since no history was available regarding 
the animals which furnished the serums. It is therefore probable that 
a number of the atypical and possibly also some of the positive reactions 
in the apparently healthy animals might have resulted from an injection 
of tuberculin, which to-day is quite extensively practiced for diagnostic 
purposes. 
