12 
Journal, of Agricultural Research 
Vol. VIII, No. i 
Inactivation at 55 0 for one-half hour was not uniformly satisfactory; 
it was found that an inactivation of 58° gave the best results. Buck’s 
method of inactivation (unpublished) was also employed, in which 
equal parts of salt solution are added to the serums and the inactiva¬ 
tion is carried at 62°. Both methods were uniformly satisfactory, 
though in a few instances Buck’s method appeared to have an advantage 
over the former. The quantity of the inactivated serum used for the 
test was 0.2 c. c. 
Table VII describes in detail the procedure of the test, in which the 
incubation time is designated as one hour. In order to obtain the best 
results in the preliminary experiments, care was taken to establish the 
length of time the racks should be kept at incubation before adding the 
hemolysin and the suspension of blood corpuscles. By subjecting 
various racks to incubations from one to four hours it was found that 
one-hour periods served to the best advantage. 
RESULTS OF TESTS 
In all 958 samples were tested, of which 816 samples were of bovine, 
120 of porcine, and 22 of human origin. A summary of the tests is con¬ 
tained in Table VIII, which also describes the lesions found on post¬ 
mortem examination of the cattle in the abattoirs. 
In order that a clearer conception might be obtained as to whether 
there exists any relation between the degree of reaction and the character 
of the disease it was deemed advisable to separate the cases into five 
groups according to the lesions found on post-mortem examination, as 
follows: 
1. A ni m als which showed no lesions of tuberculosis and which failed 
to react to the tuberculin test. 
2. Animals which showed arrested lesions with a limited number of 
small slight caseo-calcareous foci confined to the lymph glands. 
3. Animals with progressive lesions of a glandular type involving also 
some of the organs. 
4. Animals with well-marked or generalized lesions. 
5. Acute and miliary tuberculosis. 
In considering the results of these tests there appears to be no constancy 
in the reaction; and furthermore, the degree of the reaction appears 
to have no relation to the extent of the disease. It was also noted that the 
condition of the animal has apparently no effect on the reaction, which 
as a matter of fact is also the case in the subcutaneous tuberculin test, 
although in the latter advanced generalized cases may fail to respond. 
The degree of the fixation is also irregular, since the slight positive 
reactions (4*) do not occur proportionally with a greater frequency in mild 
cases than the complete fixation (+ + + +)* This must be considered a 
great disadvantage, as a slight reaction might be overlooked or might be 
obtained as a result of the slightest neglect in the standardization of the 
