10 BULLETIN 70, U. S. DEPARTMENT OF AGRICULTURE. 



appearance appeared to be active, they were of smaller sizes, ranging 

 from a pinhead to the size of a pea. Horses Nos. 110, 120, and 124 

 were killed on the same day, although they had failed to show any 

 indication of glanders by the eye test, which was also substantiated 

 by the complement-fixation test with the blood of these animals. 

 Post-mortem examination showed no signs of glanders in these animals. 



The final results are quite striking relative to the deficiency of 

 immunization against glanders by killed bacteria. 



Of the remaining horses which were kept under observation, as 

 indicated in Table 2, Nos. 117 and 119 died on October 17 and 25, 

 respectively, of acute glanders after developing the clinical form 

 of the disease. No. 86 also showed indications of the disease in 

 the early part of October. The final test on the remaining horses, 

 namely, Nos. 86, 111, 121, and 123, was undertaken in the early 

 part of January, 1914, when they were subjected to the ophthalmic 

 and subcutaneous mallein tests and also to the complement-fixation 

 and agglutination tests. All horses reacted to these different tests 

 with the exception of No. 86, which reacted to the fixation, agglutina- 

 tion, and ophthalmic tests but failed to react to the subcutaneous 

 mallein test. Two days following the tests all the animals were 

 destroyed and careful post-mortem examinations were made. The 

 results showed glanders lesions in all animals, including No. 86, in 

 varying degrees. The lungs in all cases contained numerous glanders 

 nodules most of which were in an active stage, and in horse No. 86 

 the apex of .the left lung showed a typical glanderous pneumonia 

 with the characteristic gelatinous infiltration and numerous nodules 

 of various sizes throughout the remainder of the pulmonary tissue. 



It is interesting to note that all these vaccinated horses returned 

 to the normal serum reaction of a negative case on or before the 

 twelfth week after the vaccination, as may be seen from Table 4. 

 The exposure in the corral was continued the same as during the 

 entire course of the experiments and the weekly changes of stable 

 exposure were also carried out. The appearance of the disease in 

 these remaining animals seems to offer a more substantial basis for 

 drawing conclusions as to the unsatisfactory results of these vaccina- 

 tion tests. 



From our experience with outbreaks of glanders in stables, it 

 appears that these experimental horses did not develop clinical 

 manifestations of the disease in greater proportion than is the case 

 with the average exposed horse. It is true that the exposure of the 

 horses in the experiments was continuous although not unusually 

 or unreasonably severe. Whether the horses which were included 

 in this final test possessed a certain degree of immunity as a result of 

 the vaccination, during the period including the time between the first 

 exposure and the last negative eye test, it is impossible to say; but 



