EXPERIMENT STATION BULLETINS. 409 



It has seemed desirable to determine in eacli case the limit of the 

 agglutinative power of each serum tested. In order to do this, we have at- 

 tempted to test the serum at dilutions both above and below the limit and 

 at the same time to employ only five different dilutions. This is possi- 

 ble only when we can make a close estimate as to the probable maxi- 

 mums at which agglutination will occur. Previous tests with blood 

 serum from the same animal and a knowledge of the treatment to which 

 the animal has been subjected are the only indications. The agglutina- 

 tive power of a serum, as measured by the system of dilutions, does 

 not always diminish at a ratio capable of being computed from the data 

 furnished by the observation (of a considerable number of dilutions. 

 To make this point clear, it is only necessary to study a table of reactions 

 when it will be found that a complete reaction at one dilution is followed 

 in some cases by a gradual diminution of the strength of the reaction 

 thriough several succeeding dilutions while in other cases a complete 

 reaction may be followed in unvarying intensity throughout a consider- 

 able number of dilutions. This discussion is of more general interest, 

 however, than the subject of this paper will permit. Still, we are con- 

 vinced that our understanding of the nature of the agglutination re- 

 action and the technic involved in making the test is very crude. 



CULTURES USED. 



Two cultures from different sources, but probably the same strain, 

 were used in all the tests recorded here. Comparative tests demonstrated 

 that there was no appreciable difference in the agglutinability of these 

 two cultures of B. cJvolerae suis. Indeed they must have had a common 

 source unless the B. diolerae suis found in the blood and other tissues of 

 "virus pigs" finds its way there from its alleged normal habitat, the in- 

 testines, of each pig treated. 



Culture 'S'irus 122" came fiiom the spleen of virus pig 122. 



Virus pig 122, wt. 75 lbs., was inoculated in the muscles of the ham 9-23-09 with 

 5 cc. virus blood from Expt. pig 216. The pig was killed 9 days after inoculation 

 after showing characteristic symptoms of hog cholera. 



Autopsy: Inguinal glands quite hemorrhagic; iliac glands enlarged and hemor- 

 rhagic; renal glands hemorrhagic; kidneys show few petechiae in both cortex and 

 medulla; spleen enlarged and friable. 



Culture "virus 13G" came from the spleen of virus pig 13G. 



Virus pig 136, wt. 81 lbs., was inoculated in the muscles of the ham 11-30-09 

 with 5 cc. of virus blood from virus pig 128. Was killed 11 days later after show- 

 ing symptoms of hog cholera. 



Autopsy: Cortex of inguinal and iliac glands hemorrhagic; kidneys show 

 petechiae in both cortex and medulla; spleen enlarged, dark and friable; liver 

 shows slight superficial necrosis; intestinal mucosa sprinkled with numerous 

 petechiae; lungs, hemorrhagic. 



These cultures were plated on agar and typical colonies were seeded 

 on the various media necessary for the identification of B. cJiolerac 

 suis. Infectiousness for rabbits was also determined. Pathogenicity for 

 pigs was not detemiined excejit tliat large quantities of culture "virus 

 136" were^ injected intramuscularly into an immune ]ng (Expt. 315) 

 with the result that only local abscesses were produced.* 



*The object and results of this work will l.e recorded later. 



