108 HOG CHOLEEA 



as is required in a satisfactory test, or when inter- 

 current disease or accident intervenes. 



Too much stress cannot be placed on the test, 

 for it is here that all technique leading up to com- 

 pletion of the finished product receives its final 

 confirmation. Careful observations are necessary 

 as well as strict interpretations which withhold 

 from use all doubtful serum. Regulations are a 

 valuable guide, but they themselves require skill- 

 ful interpretation, and no exact rules can be laid 

 down which will serve their intended purpose 

 under all circumstances. Is the serum highly po- 

 tent? Is it free from organisms that will injure 

 hogs into which it is injected? When test con- 

 ditions answer both questions definitely in the 

 affirmative, the serum is fit for use. If doubt re- 

 mains it may be retested, and if it has failed to 

 protect healthy pigs in average condition it should 

 be discarded. 



In our own work we greatly prefer an eight pig 

 test in which two of the serum pigs receive 10 

 mils each of serum, two 15 mils each, and two 

 others 20 mils each. We believe that these low 

 doses give much more complete information re- 

 garding the potency of the product, thus allowing 

 a greater margin of safety and adding to the con- 

 fidence with which it may be used in the field. 

 Out of the last 45 tests conducted in this manner 

 37 have passed without incident, intercurrent dis- 



