HISTORY AND ECONOMIC IMPORTANCE O 



usefulness of anti-hog-cholera serum in checking 

 the inroads of hog cholera in the field. 



Since 1908, rapid advances have been made in 

 providing for an adequate supply of serum, in 

 refining it, in working out methods for its use in 

 the field, and in regulating its production so as to 

 prevent sale of that which is contaminated or im- 

 potent. All important hog-raising states in the 

 Union have made provision to manufacture serum, 

 and scores of private laboratories which have 

 been established are being operated under super- 

 vision of the Bureau of Animal Industry. In the 

 refinement of the serum the aim has been to pro- 

 duce, at low cost, a clear, sterile, potent product 

 with good keeping qualities. This ideal is rapidly 

 being attained, but there are still serious questions 

 regarding uniform potency and keeping qualities 

 of the clear serum, and the equipment required in 

 making it is rather crude, and cannot be said to 

 have passed the developmental stage. 



Finally, it should be related that with the 

 knowledge that hog cholera can be controlled, 

 there has appeared a quickened interest in all 

 other maladies that affect swine, especially those 

 frequently complicated with hog cholera. Undue 

 importance has sometimes been attached to some 

 of these diseases, and such extravagant claims 

 have been made for certain biologies used as pro- 

 phylactic or therapeutic agents that there has 



