46 Veterinary Medicine. 



Suis until the blood of the third 2i-aA fifth day (in difiEerent cases) 

 was reached. The blood of the inoculated pig was therefore in- 

 vaded by the infinitesimal microbe from one to three days before 

 it was invaded by the B. Cholera Suis. 



Of 36 pigs injected subcutem with unfiltered serum from cas- 

 ual cases of hog cholera, all sickened, 24 died, 10 were killed 

 when moribund, and 2 recovered. Of 61 pigs injected subcutem 

 with an equal amount of serum from casual hog cholera cases, 

 but which had been passed through a Ghamberland or Berkefield 

 filter, 58 sickened, 39 died, 10 were killed when moribund, 9 

 recovered, and 3 showed no illness. Though there is here a slight 

 reduction in the mortality from the filtered product, and though 

 sickness often occurred slightly earlier from the unfiltered mate- 

 rial, this is of little account in solving the question before us. 

 That the filtered serum was free from B. Cholera Suis was shown 

 by its inability to produce these in culture tests as well as by its 

 harmlessness when inoculated on rabbits and Guineapigs. The 

 9 hogs that recovered proved immune, for all resisted when 

 placed in a pen with casually infected hogs, one died but without 

 evident lesions of hog cholera. Finally, the blood of the pigs 

 injected with the filtered hog cholera blood proved infecting^ to 

 other pigs when inoculated or fed to them. 



Assuming that due care was exercised to prevent the casual 

 introduction of B. Cholem Suis the following conclusions seem 

 warranted : 



TTie infinitesimal filterable hog cholera Bacillus Cholem Suis. 



microbe. 



Very contagious from pig to pig by simple Not contagious by exposure. 



exposure. 

 Filtered injections subcutem constantly Pure cultures injected subcutem, 



virulent, usually fatal. usually harmless to pig ; dead- 



ly to rabbit and Guineapig. 

 Injections of blood subcutem, constantly Injections of blood subcutem, 



virulent and fatal. usually harmless. 



Intravenous injections of blood constant- Blood intravenously virulent and 



ly virulent and fatal. fatal. 



Cases that recover strongly immune. Recovered cases show little im- 



munity. 



Accessory Causes. These are especially those conditions which 

 favor the transmission of the germ from animal to animal. They 

 include the reprehensible habit of allowing swine to run at large 



