Contagious or Epizootic Abortion in Cows. 
97 
A bacteriological examination of the matter which comes 
away with the foetus, or of the latter and its membranes, will 
in nearly t all cases enable an expert to diagnose a case of 
contagious abortion, but this applies only to the first day or 
two after abortion. Within less than a week diagnosis in this 
way becomes impossible. 
A material analogous to tuberculin, and termed “abortin,” 
has been employed for diagnosis, but it cannot be said that 
there is sufficient evidence to warrant an opinion as to its 
actual value. 
There are, however, two recently introduced tests for 
contagious abortion which have been proved to be remarkably 
trustworthy, named, respectively, the complement and the 
^•gg^tination test. These appear to give closely concordant 
lesults, but, inasmuch as the first is much more complicated 
and difficult to carry out, and no more accurate than the second, 
only the latter will be here described. 
The agglutination test depends upon the fact that when an 
animal becomes infected with contagious abortion a substance 
■which has a special affinity for and exerts a peculiar action on 
abortion bacilli appears in the blood. This substance is termed 
“ agglutinin.” When blood serum in which this agglutinin is 
present is added to an emulsion or suspension of abortion bacilli 
in water, it acts on these in such a way as to cause them to 
collect together in clusters or clumps, and this clumping or 
agglutination of the bacilli can be observed under the micro- 
scope. It can, however, also be made manifest to the naked 
eye, because the clumps w T hich are thus formed in a suspension 
of abortion bacilli tend to fall more rapidly under gravitation 
than the single unagglutinated bacilli do. Hence, when marked 
agglutination occurs in a test-tube, the original slightly hazy 
liquid gradually becomes quite clear and transparent, while the 
clumps of bacilli at the same time settle to the bottom of the 
tube. 
Briefly stated, the test is carried out as follows : — A sufficient 
quantity of abortion bacilli obtained from a pure artificial 
culture is added to water in such proportion as to make the 
mixture slightly hazy when a test tube containing it is held up 
to the light. Care must be taken that this suspension does not 
contain any coarse clumps of bacilli, but is for the most part 
made up of single bacilli suspended in the liquid. Measured 
small quantities of this suspension are then poured into a series 
of small test tubes and to each of these a measured quantity of 
serum from the suspected animal is added, the proportion 
of serum varying in the different tubes. In general one 
employs at least three such tubes, which respectively contain 
the serum in the proportion of — 
E 
