484 Veterinary Obstetrics 



The period of incubation is comparatively short, or we 

 might say that it corresponds quite closely to that observed in 

 most contagious diseases of animals. According to our personal 

 observations, the incubation period usually ranges from 8 to 10 

 days. Guillerey considers the period of incubation from 3 to 5 

 days in virulent outbreaks. In the milder cases, according to 

 his observations, the duration of incubation was from 10 to 18 

 days. This observation is interesting in that it would appear to 

 indicate that the earlier during gestation infection occurs, the 

 longer the period of incubation. The observations of G. in ref- 

 erence of the period of incubation do not materially conflict with 

 our own. He gives, in a supplementary table, the average dura- 

 tion of incubation in the mild outbreaks as 12 days and in the 

 severe outbreaks as four days. 



The bacteriology of infectious abortion in mares has not been 

 determined in a manner universally acceptable. Ostertag found, 

 in the blood of the fetal heart, in the thoracic cavity, and in the 

 intestinal tract, short streptococci which were readily stained by 

 the Gram method. In serum agar, this micro-organism grew in 

 very small areas scarcely visible to the naked eye, while in a 

 stick culture it assumed the form of a thread-like colony through- 

 out the length of the tube. It also grew in a serum bouillon 

 and caused, after two days, a general cloudiness of the entire 

 mass. Sometimes Ostertag secured pure cultures from the body 

 of the aborted fetus, while from the surface of the chorion he 

 obtained the same cocci in company with various bacteria. 



In one experiment Ostertag injected a pure culture of this 

 streptococcus into the jugular vein of a pregnant mare. Twenty 

 days later the mare aborted. 



A question of the -correctness of the findings of Ostertag is 

 raised by the fact that he is in apparent conflict with Bang, who 

 finds in the infectious abortion of the cow a short bacillus instead 

 of a streptococcus. Bang even claims, as we shall dwell upon 

 more particularly in the next article, that his abortion bacillus is 

 capable of producing abortion in almost any pregnant animal, 

 and would apparently have us believe that the contagious abor- 

 tion of various animals is identical and interchangeable. As we 

 have already stated, we consider that clinical evidence shows 

 very clearly the non-identity of infectious abortion in the vari- 

 ous species of animals. Nevertheless, we should expect that 



