PEEPABATION OF ANTI-HOG-CHOLERA SERUM 87 



trifuge of which the essential part is an enclosed, 

 revolving, perforated cylinder; others pour the 

 contents of the jars directly into funnels into 

 which one or more thicknesses of sterile gauze 

 have been placed ; still others empty the jars into 

 perforated funnels which fit into the tops of tall re- 

 ceptacles into which the fluid drains, and near the 

 bottom of which is a turncock for drawing it off. 

 Formerly clot presses were used universally as a 

 final means of extracting the last drop of blood 

 from the fibrin and clot, but this practice is gradu- 

 ally being abandoned. It increases the yield but 

 little, and adds unnecessary debris to the blood, 

 whether it is serum or virus. In all methods of 

 handling the final act is to strain the blood through 

 gauze, after which it is placed in storage bottles 

 and refrigerated pending the time when it is re- 

 quired for hypering. The blood of several virus 

 pigs is mixed after autopsies have confirmed its 

 fitness for use. 



This "hypering virus " may be kept forty-eight 

 hours or even longer, but it is best to use it after 

 it has been refrigerated about one day. It is well 

 to strain it a second time just before it is to be in- 

 jected. Preservative is never added to hypering 

 virus. 



The autopsy. The two essential requirements 

 for a virus pig are that it shall show complete evi- 

 dence that it was suffering with acute hog cholera 



