98 
Contagious or Epizootic Abortion in Cows. 
1 in 50 of emulsion, 
1 in 100 of emulsion, 
1 in 200 of emulsion. 
In carrying out the test with any suspected serum it is 
necessary to make at the same time two similar sets of, tubes, 
one containing serum from an animal which is known to have 
been- infected with contagious abortion, and one with serum 
Fig. 3. — The three right hand tubes marked “Negative Control” each contain serum from a healthy cow. 
and. in each case, the emulsion of abortion bacilli retains its original cloudy appearance. 
The three tubes marked “Positive Control” each contain serum from a cow known to be affected with 
contagious abortion. The tube nearest the left shows complete agglutination, the bacilli have fallen to the 
bottom and lelt the liquid quite clear. In the middle tube the agglutination has been less complete, and 
in the one to the right it is only recognisable. 
The figures beneath the tubes indicate the proportion of serum present in each. 
from an animal which is known to be free from contagious 
abortion. One also includes in the test a single tube of bacterial 
emulsion without any serum whatever. The whole of these 
tubes are placed in an incubator at the body temperature for 
twenty-four hours, at the end of which time the tubes are 
inspected. 
NEGATIVE CONTROL 
Im50 IinIOO Iin200 
POSITIVE CONTROL 
Iin50 IinIOO Iin200 
