EXPERIMENT STATION REPORTS. 171 



pose of giving two herds of dairy cattle the vaccine^rcatment for infectious 

 abortion. 



The following papers have been submitted during the past year: 



Studies in infectious abortion. Presented at the annual meeting of the 

 American Veterinary Medical Association, Columbus, Ohio, August, 1920., 

 Journal of the American Veterinary Medical Association, Vol. II, No. 5, 1921. 



The accurate diagnosis of bovine infectious abortion. Presented at the 

 annual meeting of the U. S. Live Stock Sanitary Association, Chicago, Illinois, 

 December, 1920. Vide annual report for 1920 of the U. S. Live Stock Sani- 

 tary Association. 



The bleeding of cattle and swine for the blood test for infectious abortion. 

 Vide Michigan Agricultural Experiment station cjuarterly, November, 1920. 



The importance of an increased carbon dioxide tension in growing Bad. 

 abortus (Bang). Presented by Ward Giltner at the annual meeting of the 

 American Society of Bacteriologists, Chicago, December, 1920. Vide 

 Cornell Veterinarian, July, 1921. 



The problems in the investigation of infectious abortion which were sul)- 

 mitted in the report for 1919-20 have been studied further together with new 

 problems whfch have suggested themselves in the course of the investigation. 

 Very little progress has been made in one or two of the important problems 

 owing to the limitations of the experimental herd and to the fact that the same 

 animals could not be used for two investigations at the same time. 



We have housed, in the experimental barn at the present time twelve cows, 

 fourteen heifers, one bull and two male calves. In addition I have adcUxl 

 seven sows for the purpose of conducting investigations in swine abortion. 



The problems which are under investigation are : 



1. The immunization of cows and heifers against infectious abortion using 

 killed and living cultures of Bact. abortus (Bang). 



Owing to the large number of factors involved, the solution of this problem 

 is slow. A large number of animals must be employed and experiments 

 repeated before conclusions can be drawn. The data which have accumu- 

 lated from our own experimental herd while yet few, are very encouraging. 

 Several herds in the State have been treated, but sufficient time has not 

 elapsed for the tabulation of the final results. 



2. The routes through which Bad. abortus gain entrance to the body. 

 This problem is still under investigation. 



3. The bactericidal effect of different chemical agents in vivo against Bad. 

 abortus. The work on this problem did not progress very rapidly during the 

 past year owing to the employment' of the anim.als in other experiments. 



4. A study of the antigenic and pathogenic properties of many strains of 

 Bad. abortus. The work on this problem is nearing completion, and will 

 soon be ready for publication. 



The specificity of the intradermal test and its value in differentiating be- 

 tween infection and immunity. 



This problem has not progressed as rapidly as was planned, owing to the 

 discovery that the abortin when injected into the animal would give rise 

 to the development of agglutinating and complement fixing antibodies in 

 the blood of the animal in question. Since the majority of the animals are 

 on immmiization experiments, and others are under oljservation for the re- 

 turn of the above antibodies, the appearance of antibodies from the injection 

 of abortin is very misleading and interferes with the correct interpretation of 

 results. 



