354 



DISEASES OF SWINE 



the simultaneous treatment. As a result, the army of toxins meets 

 with an equally well-trained defensive army of antibodies, and the 

 battle is on. The cells, stimulated by calls for help from the strug- 

 gling antibodies at the front, immediately put on full steam in 

 the turning out of new receptors that enter the blood as germ- 

 destroying antibodies. These swell the number in the blood- 

 stream until they reach an enormous total by the end of the first 

 week or ten days. The invading foe has long since been van- 

 quished, and the cells are keeping up the supply of antibodies to a 



Fig. 64.— Tail bleeding for serum. (Photo by Dr. Geo. R. White.) 



high standard to prevent any surprise by a lurking germ enemy. 

 The blood is now at its highest standard of strength, and this is 

 the time at which it should be drawn and prepared for use in de- 

 fense of other hogs that may be threatened with attack. 



Bleeding for Serum. — The animal is now brought back into the 

 operating room and prepared for bleeding. This preparation con- 

 sists in restraining the animal again in a suitable crate or upon an 

 operating table. The animal is weighed, and this weight compared 

 with that on the date of hyperimmunization. The animal should 

 show a gain in weight between these two dates of approximately 



