PREPARATION OF ANTI-HOG-CHOLERA SERUM 93 



which it has been placed in the vein, as well as by 

 individual differences in hogs that are not well 

 understood. When the required quantity of virus 

 has been injected, the pinch-cock is closed, the 

 needle is withdrawn, and the hog is wheeled away 

 and released. 



This describes the hypering operation in its 

 simplest form with everything favoring the oper- 

 ator. Volumes could be written about the at- 

 tempts that end in failure. Practice is important, 

 but a natural surgical touch amounting almost to 

 instinct is required of the expert operator, and 

 even he may experience unexplainable lapses in 

 the execution of his technique. However, most of 

 the annoyances experienced may be overcome, and 

 it seems desirable to include a few suggestions 

 which may aid the beginner in his work. 



At first select hypers with ear veins straight 

 and prominent; later it will be possible to hyper 

 practically all subjects : begin the operation soon 

 after the ear has been shaved ; otherwise the vein 

 may recede and be very difficult to distend so that 

 the needle may enter it : use a needle with a per- 

 fect point ; a dull one will roll the vein under it : 

 Hold the ear out straight; otherwise the skin will 

 be relaxed and the vein will be unnecessarily tor- 

 tuous : after the needle has entered the vein do not 

 release it until it is clamped firmly in position; 

 the nub may drop carrying the point upward and 



