96 
Contagious or Epizootic Abortion in Cows. 
reveals no evidence of disease, the existence of which can 
only be proved by the agglutination or complement tests. It 
is of interest to notice also in this connection that although at 
the post-mortem examination of infected pregnant cows abortion 
bacilli have never been found external to the womb, it is 
obvious that they must in many if not in all cases exist in 
other parts of the body at a certain stage of the disease, for, to 
account for the fact that cows can be infected by the mouth, 
one must assume that the bacilli find their way into the 
bloodstream, and by that means reach the uterus. The known 
facts also make it practically certain that an actual multiplica- 
tion of the bacilli must take place either in the blood or in 
other organs besides the uterus. 
It has already been stated that abortion is not a constant 
result of infection even in pregnant cows, and the fact must be 
emphasised here. That many infected cows carry their calves 
to full term has long been suspected, but the fact has now been 
proved by the employment of the agglutination test in large 
numbers of infected herds. In such circumstances one often 
finds that cows which have recently calved at full term are 
condemned by the test, or that pregnant cows condemned 
by the test do not afterwards abort. There is, of course, 
nothing remarkable in this fact, for a considerable amount 
of structural disease is required in order to provoke the womb 
to expel its contents prematurely, and the normal period 
of parturition may arrive before that point has been reached. 
The reader may here be warned not to jump to an explana- 
tion of the fact which may appear to him much simpler, 
namely, that the agglutination test is in error when it con- 
demns a cow that carries her calf to full term. Judgment 
with regard to that point may be suspended until the evidence 
bearing on the reliability of the agglutination test has been 
dealt with. 
Diagnosis . When a cow has just aborted there are various 
ways in which one may attempt to determine whether the act 
has been caused by infection with the abortion bacillus or has 
been due to some other cause. 
Some guidance in the matter may be obtainable by con- 
sidering the condition of the cow, the ease or difficulty with 
which the foetus has been expelled, and the appearance of the 
latter and its membranes. Thus, absence of any indication of 
illness on the part of the cow and almost effortless expulsion 
of the foetus are points in favour of the case being one of 
contagious abortion. It is, however, not necessary to discuss 
the value of such evidence at any length, for nothing is 
more certain than that there are many cases in which the 
cause of the abortion cannot be determined in that way. 
