OSTERTAG'S STREPTOCOCCUS IN ABORTION IN MARES 321 



to work out an accurate method of diagnosis by means of vaccine or 

 serum tests. An agglutination test was devised, based upon the same 

 principle and technique as the agglutination test for glanders. It 

 was found, however, that the difference between the agglutinating 

 powers of the serum of a cow affected with abortion and that of 

 normal animals was too slight to inspire confidence in such a test. 

 It was found during these experiments that the milk of an animal 

 which had aborted possessed agglutinating properties up to 1 to 25, 

 but owing to the opacity caused by the addition of milk to a culture 

 the lacteal fluid was found unsuitable for such agglutination tests. 

 Another test tried was one based upon the principle of complement 

 fixation, which has found such wide application in the diagnosis 

 of latent human syphilis (see Chapter VII). The serum for this 

 test for epizootic abortion is obtained from blood drawn from the 

 jugular veins of the cows. The antigen is prepared from a pure 

 culture of the abortion bacillus emulsified in physiologic salt solution. 

 The complement is derived from the serum of guinea-pig's blood; 

 the hemolytic amboceptor from the serum of goats sensitized for 

 ox-blood corpuscles, and the latter were, of course, used for the final 

 hemolytic test. As controls the blood serum of healthy cows and of 

 cows infected artificially with the abortion bacillus were used. Un- 

 fortunately, the results of these complicated and painstaking tests 

 of the authors, the first to apply the principle of complement fixation 

 to the diagnosis of an animal disease, were not uniform and trust- 

 worthy. The last series of experiments for the diagnosis of epizootic 

 abortion was made with a vaccine prepared according to the principles 

 which underly the preparation of tuberculin and mallein. This 

 abortin, derived from pure cultures of the abortion bacillus, was 

 injected, and the following conclusions as to its value as a diagnostic 

 were drawn: "It would appear that a rise of temperature to 104 F. 

 or more after the injection of abortin may possibly be indicative of 

 infection, but it will be necessary to carry out a large number of tests 

 in practice before deciding upon the value of the method of diagnosis." 



OSTERTAG'S STREPTOCOCCUS IN ABORTION IN MARES. 



An extensive epizootic of abortion among mares was studied in 

 1899 and 1900 by Ostertag. While he expected to find as its cause 

 Bang's bacillus, he failed entirely in spite of the use of the proper 

 culture medium to encounter this organism, but instead of it, he 

 obtained from the edematous fluid between the uterine mucosa and 

 the fetal membranes, from the heart's blood, the pleural fluid, and the 

 gastric contents of the dead feti a short, immobile, Gram-negative 

 streptococcus. The organism was difficult to cultivate; it grew best 

 in serum bouillon, serum agar, and the transudate of dead feti. The 

 fluid media are clouded by these growing streptococci in two days, 

 21 



