90 
Contagious or Epizootic Abortion in Cows. 
bodies of infected animals and by some means or another is 
passed on from the diseased to the healthy individuals. It is 
therefore not surprising that contagion should long ago have 
been suggested as the probable cause of multiple cases of abor- 
tion among cows. The idea is more than a century old, but 
what is surprising is that in spite of its obvious reasonableness 
it is only in quite recent times that it has found anything 
like general acceptance. In what follows it will be shown that 
the occurrence of multiple cases of abortion in a herd is nearly 
always due to the spread of a particular contagious disease 
among the cows, meaning by the word “ particular ” that the 
disease is caused by a definite species of organism which can 
be recognised and identified by a number of special features 
or characteristics. It may be observed that in the preceding 
sentence it is not asserted that this organism is responsible 
for all multiple cases, or outbreaks, of abortion in the same 
herd, for it is obvious that some of the earlier mentioned 
causes may occasionally operate simultaneously on a considerable 
number of pregnant animals and bring about abortion. More- 
over, it must be admitted as conceivable that other microbes 
than the one referred to above may be capable of causing 
abortion in cows, and that there might thus be two or more 
different kinds of contagious abortion in these animals. The 
writer, however, is in possession of evidence which proves that 
beside the special organism which in the remainder of this 
article will be called the abortion bacillus all other causes of 
abortion among cows sink into insignificance. 
The abortion bacillus . — The accompanying figure (Fig. 1) 
may serve to give the reader a fairly correct idea of the shape of 
abortion bacilli, and also of their size, if it is remembered that 
they are in reality two thousand times smaller than they here 
appear on the paper. In cases of contagious abortion, the bacilli 
are always present in large numbers in the diseased womb, and 
in the discharges and afterbirth. A pecular feature of the bacilli 
is that they are often collected together into large clusters 
or clumps, one of which may contain hundreds of individual 
organisms. 
There is no great difficulty in inducing the bacilli to grow 
outside the body under entirely artificial conditions in test tubes 
or flasks containing various nutritive materials of which the 
basis is meat extract. It does not appear to be necessary to 
describe here in any detail the various appearances presented 
by artificial crops or cultures of the abortion bacillus, but one 
of its so-called cultural characteristics may be described because 
it is of value for the identification of the organism. The 
medium or nutritive substance in which this peculiar appearance 
is exhibited is one which is transparent and solid at temperatures 
