198 INFECTIOUS ABORTION IN CATTLE 
15. Tworr. The agglutination and complement-fixation reactions in animals 
experimentally inoculated with Johne’s bacillus, etc., Centralblatt fiir Bakt. Originale, 
Bd. LXVI (1912), S. 316. 
16. Twort anp Craig. The Pathogenicity of Johne’s bacillus compared with 
that of Other Acid-Fast Bacilli for some of the Jaboratory animals, Centralbl. ftir 
Bakt. Originale, Bd. LX XVIII (1913), S. 455. 
17. Twort anp Incram. A Method for isolating and cultivating the IMycobac- 
terium enteritidis chronice pseudotuberculose bovis Johne, and some Experiments on the 
Preparation of a Diagnostic Vaccine for Pseudotuberculous Enteritis of Bovines, 
Proceedings Roya! Society, B., Vol. LX XXIV (1912). 
18. Tworr and INcram. Further Experiments with the Mycobacterium 
enteritidis chronice pscudotuberculose bovis Johne, and with Vaccines prepared from 
this Micro-Organism, Centralblatt fiir Bakt., Bd. LX VII (1912), S. 126. 
19. Twort anp INcram. Johne's Disease. London, 1913. 
INFECTIOUS ABORTION IN CATTLE 
Synonyms. Cattle abortion; contagious abortion; “picking,” 
“slipping,” ‘‘casting.”’ 
Characterization. The disease known as infectious abortion con- 
sists in the expulsion of the immature fetus, usually before it has 
sufficiently developed to live after birth, by a large proportion of 
pregnant animals that are kept together. Usually the abortion 
occurs in cattle between the fifth and eighth month of gestation. 
It is characterized by certain morbid changes in the uterine mucosa 
and fetal membranes. It usually affects the young cows. Williams 
defines infectious abortion in cattle as a widespread and highly 
destructive chronic infection having its chief seat in the genital organs 
of cattle and expressing itself by a variety of symptoms, four of the 
most prominent of which are sterility, expulsion of fetus, premature 
birth and metritis with retained fetal membranes. 
Other domesticated animals such as mares, swine and sheep suffer 
from infectious abortion but the cause seems to be different. Surface 
has described an epizodtic in guinea pigs caused by the Bang organism. 
History. Abortion in epizoédtic form has been recorded from very 
early times. Mascal, in 1859, gives directions in his work on cattle, 
“How to keep cows which are great bellied with calf.” In Germany 
the disease seems to have existed in a somewhat severe form in the 
latter part of the eighteenth century. 
A number of important scientific investigations have been made 
into its nature in France by Nocard, 1885; in Great Britain, by a com- 
mittee appointed in 1886 by the Highland Agricultural Society of 
Scotland consisting of Drs. Woodhead, Aitken, M’Fadyean and 
