INFECTIOUS DISEASES 195 



securing the animal. Various devices are used in making 

 the injection. The principle involved is to force the virus 

 into the vein sb^ly. The virus should be near the body 

 temperature when injected. In the intra-muscular meth- 

 od the virus is injected in the interstices between the 

 muscle bundles, selecting two, three, or four locations, 

 as the inner thigh muscles and the sub scapular region. 

 The intraperitoneal injection is made by passing a long 

 needle through the abdominal parietes into the peri- 

 toneal cavity. 



The hyperimmunes are kept in clean, sanitary pens 

 and a temperature record maintained in order that the 

 producer may know when the reaction is over. When 

 the temperature assumes the normal the blood contains 

 the antibodies. Two methods of bleeding hyperimmunes 

 are in use the slaughter method and tail bleeding. By 

 the slaughter method practically all of the blood is ob- 

 tained. By the tail-bleeding process from two to four 

 bleedings are made, and the swine are re-hyperimmunized, 

 and after the reaction they are used for bleeding. Some- 

 times the hyperimmune is tail bled for one, two, or three 

 times and then slaughtered. Each method has some 

 advantages and some disadvantages. The slaughter 

 method is the most rapid in other words, more serum 

 can be produced in a given length of time than by tail 

 bleeding. Tail bleeding is the most economical method 

 of producing serum, and antiseptic precautions can be 

 carried out more effectually. 



Proper equipment is required for either process, and 

 the instruments, bottles, and other utensils used must be 

 sterile and the environment must be conducive to asepsis. 



The blood obtained from hyperimmune swine is 

 whipped, the fibrin being removed and the remaining 

 portion of the blood filtered through gauze. "When ob- 

 tained by the slaughter method, the blood from each hog 

 is kept separately until the carcass is autopsied and the 

 absence of cholera and other diseases is demonstrated. 

 The blood may also be kept in one container. Centrifu- 

 gation of the blood is being practiced by some producers, 



