EXPERIMENT STATION BULLETINS. 655 



lesions and blood reactions when five cubic centimeters are inoculated 

 into the abdominal cavity of guinea-pigs. 



A lower antibody and cellular content in the strippings than in the 

 fore milk seems to indicate that infection is slight and that Bad. abortus 

 is not present in sufficient numbers to cause infection with the five 

 cubic centimeters used for inoculation. 



The agglutination test is of value in studying the presence of Bad. 

 abortus in milk when it is desired to study a large number of samples. 



If Bad. abortus is found to be pathogenic for humans, this test may 

 be of value in safeguarding certified and all unpasteurized milk. 



If this disease is found to be spread to calves through ingestion of 

 infected milk this test may prove a means by which such milk could 

 be eliminated for this purpose. 



SUMMARY AND CONCLUSIONS. 



Part II. 



We have no proof that Bad. abortus is pathogenic for human beings. 



It is j)ossible to cause antibodies for Bad. abortus to appear in the 

 blood serum of adults by feeding a milk which is naturally infected witli 

 Bad. abortus and which contains the Bad. abortus antibodies. 



Antibodies appearing as above apparently indicate a passive immunity 

 due to the absorption in the intestine of tlie antibodies present in an 

 infected milk. 



SUMMARY AND CONCLUSIONS. 



Part III. 



Twenty-seven per cent of the cattle studied upon seven farms had 

 Bad. abortus infected udders. 



The infection was either present in a high percentage of the animals 

 of the herd or was entirely absent indicating the very infectious nature 

 of the disease. 



Once the infection is established in the udder the milk becomes a car- 

 rier of Bad. abortus and a possible source of the infection for years. In 

 no instance has the udder infection died out after being firmly estab- 

 lished during the three years that observations have been made. 



The rear quarters are usually the first to show the Bad. abortus in- 

 fection indicating that the genital discharges and switching of the tail 

 are its source. The infection may then be carried to the front quarters 

 upon the hands. 



The age of the cow apparently has no connection with the first appear- 

 ance oi the infection. 



