1898.] MICROSCOPICAL JOURNAL. 177 



stock pens, infected farms, and all other places harboring 

 the contagion. The other is the treatment of diseased and 

 exposed animals with antitoxic serum. 



The stamping-out method is attended by many difficul- 

 ties and limitations. Farmers often object to the slaughter 

 of exposed animals which are still healthy, unless paid 

 more than the animals are worth, and they are unwilling 

 to have their breeding stock killed so long as there is a 

 chance of saving a part of it. On the other hand it is 

 embarrassing, if not impossible, to utilize in any way the 

 carcasses of exposed animals which have not yet de- 

 veloped symptoms of disease, and to destroy these adds 

 largely to the expense. Again, it is next to impossible 

 to control transportation and the disinfection of cars so 

 as to prevent constant reinfection. The disinfection of 

 farms is also a troublesome matter, as the germ of hog 

 cholera has great vitality, and is able to maintain its ex- 

 istence and virulence in the soil, in moist organic matter 

 and even in mater, for several months. Finally, the 

 wide distribution of the disease, the ease with which the 

 contagion is carried, the numerous agencies which contri- 

 bute to its spread, are all elements which increase the 

 gravity of the problem and militate against the success 

 of the stamping out method. 



The use of antitoxic serum appears at present to he a 

 much more promising method of diminishing the losses, 

 and it is possible that it may he combined with sanitary 

 regulations, such as quarantine of infected herds, disin- 

 fection of premises, and supervision of transportation, 

 so as to give the advantages of the stamping-out method 

 while avoiding many of its embarrassments. The serum 

 is prepared hy inoculating horses or cattle with cultures 

 of the disease germs and repeating these inoculations 

 with gradually increasing doses until the animals have at- 

 tained a high degree of immunity. The blood of such 

 animals injected under the skin possesses the power of 



