EXPERIMENT STATION BULLETINS. 407 



STUDIES OF AGGLUTINATION REACTIONS IN HOG CHOLERA 

 DURING THE PROCESS OF SERUM PRODUCTION. 



{Continued.) 



I. INTRODUCTION. 



PURPOSE. 



Tlie purpose of this paper is to set forth the results of experiments 

 made in an effort to complete the work previously published.^ We are 

 able to present a greater amount of data coverinj; some of the points 

 already considered and, in addition, a more or less comprehensive ac- 

 count of many features not previously considered. 



A scientific understandincr of swine epizootics, covering such points 

 as their etiology, serum therapy, and control, demands an answer to 

 the preplexing question of the relation of B. cholerae suis (B. suipesUfer) 

 and Bact. septicacmkie hemorrlmgicae {Bad. smsepticmn) to these dis- 

 eases. We have concerned ourselves only wnth the former of these or- 

 ganisms, the latter not having been isolated by us. As a result of our 

 preliminary work, we were encouraged in the belief that a study of ag- 

 glutination reactions in all the various stages of serum production might 

 furnish a positive solution for some of the unsettled problems. We also 

 hoped that there might be some definite relation between the agglutina- 

 tive power of a serum toward B. cholerae suis and its immunizing power 

 in vivo. In other words, we hoped to standardize the serum by the 

 agglutination test. 



PREVIOUS RESULTS. 



Our work, in accord with that of many others, shows the pathogenic- 

 ity of pure cultures of B. clwlrroe stois ffor swine under certain condi- 

 tions. As a result of a limited number of observations, we have con- 

 cluded that, "Pigs immunized according to the Turner-Kolle method 

 may withstand intravenous injections of virulent cultures of B. cholerae 

 suis." We are not aware of any one having demonstrated an outbreak 

 of hog cholera due to B. cholera suis only,* excluding the possibility of 

 the presence of the filterable virus as an etiological factor. A careful 

 study of the literature added to our experience with hog cholera in 

 connection with the production and application of Dorset-Niles serum 

 leaves us undecided as to the necessity of opposing an artifl^cial im- 

 munity against an organism regarded by many, as Hottinger- puts it, 

 as a colon-like organism invading the blood from its habitat, the intes- 

 tinal canal, and possessing only acquired pathogenic properties. What 



* The work of Dammann and Stedefeder (Rep, 4) may furnish afpofsiHeexceptiop tothisftatenient 



