PREPARATION OF ANTI-HOG-CHOLERA SERUM 103 



taminated, and which, in any event, is sure to 

 hasten coagulation of the blood. 



We have not found defibrinating during the 

 bleeding process either necessary or desirable. If 

 it is done by shaking the jar into which the blood 

 is flowing, it causes the hog to struggle, thus re- 

 tarding the bleeding process and rendering break- 

 ing of the vacuum imminent ; and if it is done by 

 any device which renders shaking unnecessary 

 during the time the blood is being drawn, com- 

 plete defibrination can be brought about only by 

 shaking the jar after bleeding is discontinued. 

 On the other hand, if the hog is allowed to lie per- 

 fectly quiet, and if moderate and steady traction 

 is applied after the vacuum is established, bleed- 

 ing takes place rapidly, and almost without excep- 

 tion perfect defibrination will be secured if the 

 blood is shaken immediately after bleeding is com- 

 pleted. Individuals differ, but the average hog 

 bleeds best under about fifteen inches of vacuum. 

 Contrary to what might be expected, a more per- 

 fect vacuum than this usually tends to retard 

 bleeding rather than to hasten it. 



Each hyper is bled once each week during a 

 series of from two to four bleedings, after which 

 it may be rehypered at any time. In rehypering 

 only 21/2 mils of virus per pound body weight are 

 required. Following this second dose of virus a 



