100 
Contagious or Epizootic Abortion in Cows. 
in the incubator. The appearances presented by the different 
sets of tubes can be gathered from the accompanying 
illustrations (Figs 3 and 4). « ,, 
When it is declared that this test is a valuable one tor the 
diagnosis of contagious abortion, that is equivalent to stating 
that in the immense majority of cases blood serum from an 
animal which has not been infected with contagious abortion 
will not agglutinate emulsions of abortion bacilli in the propor- 
tions given above, but that blood serum from animals that have 
been infected with contagious abortion will cause agglutination 
in these proportions. With regard to the first of these points, 
it may be stated that McFadyean and Stockman 1 tested blood 
serum from 535 presumably healthy cattle, viz., 4b5 steers, 
34 bulls, 6 heifers and 10 calves, and found that in only three 
cases (2 bulls and 1 steer) did the blood serum cause complete 
agglutination in the strength of 1 in 50. . The history of these 
three animals was not obtainable, but, since it is now known 
that both steers and bulls can be infected with contagious 
abortion, it would not be justifiable to regard the agglutination 
in these cases as accidental, that is to say, resulting from 
something else than previous infection with abortion bacilli. 
However, even allowing that they were of that nature, it is 
important to observe that, if one had been relying upon the 
agglutination test to determine whether any of these 535 
animals had been infected with contagious abortion, an error 
in diagnosis would have been made in only three cases. 
Turning next to the other point, viz., the question whether 
the blood serum of infected animals generally or always causes 
agglutination, it may be stated that the authors above mentioned 
tested blood serum from 127 cows which had actually aborted 
or which came from herds in which cases of abortion had 
recently occurred, and they found that in fifty of these cases 
complete agglutination occurred in serum dilutions of 1 in 50. 
More recently blood from over 2,000 cows belonging to herds 
in which cases of abortion had recently occurred has been 
tested at the Royal Veterinary College, and the results (of 
which details will hereafter be published) support the opinion 
that with few or no exceptions blood serum from cows which 
have aborted from infection with the abortion bacillus will 
cause complete agglutination in serum dilutions of 1 in 50. 
The great value of this test, however, lies in the fact that it 
enables one to detect the disease during its early stages, or, at 
least, before abortion has occurred. It can also be relied upon 
to determine the nature of an abortion although weeks or even 
months have elapsed since the act. 
1 Journal of 'Comparative Pathology and Therapeutics , Yol. xxv., page 22 
