MANUFACTURE OF HOG-CHOLERA SERUM 341 



instruments should be perfectly clean and should be handled by 

 no one except the operator. It is also advisable for this man to 

 wear a perfectly clean white gown or white duck suit, a clean one 

 being provided every morning. 



Just as soon as the animal ceases to bleed a clean cotton stopper 

 should be inserted into the bottle, to prevent entrance of dust 

 and dirt from the air. These bottles and corks should, of course, 

 be prepared beforehand by thorough washing of the bottles, 

 followed by rinsing in boiling water and sterilization with dry 

 heat. The corks should be in the bottle at time of sterilization 

 in the oven, and in this manner they are sterilized at the same 

 time with the bottles. 



The virus blood should be immediately shaken as soon as drawn 

 for the purpose of preventing the formation of a clot. This can 

 be done by hand or in a regular machine provided for the purpose. 

 In small plants the virus bottles are usually shaken by hand for 

 several minutes. This causes all the clot-forming materials to 

 gather in shreds, and leaves the balance of the blood as a clear, 

 red liquid. 



After shaking for a few minutes, the blood is then poured into 

 a large filter funnel and filtered through several layers of clean 

 cotton or gauze. This filters out all the clot and allows only the 

 serum and blood cells to pass through. It is now received in 

 another perfectly sterile bottle, corked with a clean cotton stopper, 

 and set aside for future use. This filtered blood constitutes the 

 finished virus, which is used for injection into the immune animals 

 for the purpose of stimulation of the production of immune bodies. 



There is one other method of drawing virus that is practised 

 by a few serum manufacturers. This is by means of injection of 

 salt solution into the peritoneal cavity and later withdrawing this 

 fluid. About 1000 to 1200 c.c. of normal salt solution are injected 

 into the peritoneal cavity of the virus animal. Two hours later 

 the animal is killed and the salt solution recovered from the abdo-' 

 men. This method is used by Dr. Craig at Purdue University, 

 but does not seem to meet with any very general favor by other 

 serum manufacturers. Dr. Craig, however, reports very good 

 success with the method, and the serum produced at the Purdue 

 plant is well above the average in quality. Still another means of 



