352 DISEASES OF SWINE 



of worthless serum following the use of this method of hyperim- 

 munization. Not only is the quality of serum obtained by the 

 use of the intravenous method more reliable, but it is also far 

 less liable to contain bacterial contamination than that which is 

 prepared by the subcutaneous system. 



There is another disadvantage, from an economic standpoint, 

 in the use of .the subcutaneous method. This is the amount of 

 virus necessary for use. With the injection under the skin all 

 operators agree that it is necessary to use a much greater quantity 

 of virus blood than when giving the same virus by the intravenous 

 system. As the cost of the virus is one of the main expenses con- 

 nected with manufacture of serum, this is a point worthy of serious 

 consideration. It is desirable to obtain a serum at the lowest 

 possible cost consistent with a high-grade product, and if we can 

 cheapen the cost by means of the intravenous method and get 

 a better serum, there is no question in the wisdom of the course 

 being followed in adopting this plan of hyperimmunization. 



Still another item of expense that is added in the use of the 

 subcutaneous method is the disposition of the carcass of the hyper- 

 immune after final bleeding. In many cases that have been treated 

 by the subcutaneous method such enormous abscesses form that 

 the carcass cannot be used for food after slaughter. This means 

 a considerable loss to the manufacturer, as with the intravenous 

 method the body of the animal can be disposed of in the usual 

 manner. There is nothing connected with the manufacture of 

 serum that in any way lowers the value of the meat for food. 

 In a large plant the condemning of even 10 per cent, of the car- 

 casses for abscess would mean a big loss at the end of the year. 

 The price of serum is high enough at best, and we should practice 

 every possible economy to get the cost of production to the lowest 

 possible figure, and make the treatment available to the greatest 

 possible number of farmers and stockmen. The high cost of the 

 treatment is to-day one of the biggest drawbacks to increase in 

 number of serum-treated herds. 



The Intraperitoneal Method. — There is still remaining a 

 third method of hyperimmunization that is worthy of mention. 

 This consists in injecting the virus not beneath the skin, but 

 directly into the peritoneal cavity itself. This plan has been 



