238 HOG CHOLEBA 



mumzing. When the effectiveness of serum-virus 

 immunization was first demonstrated the demand 

 for these products far exceeded the supply, and 

 hasty preparations were made to produce them in 

 enormous quantities. Enthusiasm for immuniza- 

 tion ran high, and it was looked on as the final 

 solution of the hog cholera problem. Men with- 

 out previous experience with disease and with 

 no fundamental knowledge of the processes that 

 produce immunity were drafted into service to 

 produce and use products potentially capable of 

 doing great harm. It was the accepted belief that 

 all hogs should be immunized, that the process of 

 immunization was a simple one requiring only a 

 low grade of mechanical skill, that serum and 

 virus could be administered without a suggestion 

 of danger, and that the hogs receiving them were 

 from the moment the doses were administered 

 permanently immune to hog cholera. It is little 

 wonder that impotent serum was sent out, that 

 potent serum often fell into unskilled hands, and 

 that some of the laboratories that featured " virus 

 q. s. with all serum orders " sometimes sent out 

 quantities that were just a little more than suffi- 

 cient. 



The Bureau of Animal Industry laboratory in- 

 spection service with the aid of many far-sighted 

 serum companies has done much to correct these 

 initial evils. The sale of impotent serum for use 



