PROPHYLACTIC IMMUNIZATION OR VACCINATION 



673 



mass cureted off with a special, spoon-like curet and collected in a 

 sterile vessel. After the curetage, serum exudes from the excoriated 

 base of the vesicle, and ivory tips may be charged in this. The sticky 

 and pulpy exudate is then mixed with four times its weight of glycerin 

 and water (50 per cent, glycerin, 49 per cent, water, 1 per cent, phenol), 

 and this is done most effectively by passing the mixture between the 





FIG. 131. PRODUCTION OF COWPOX VACCINE. 



Note the lines of cowpox lesions over the abdomen and flanks of the calf. The 

 surgeon is about to cleanse this area in a thorough and careful manner, after which 

 the cowpox material is removed with a curet and collected in a sterile vessel. All 

 precautions are taken to insure as thorough aseptic technic as possible. 



rollers of a Doring mill. The glycerinated pulp is allowed to stand for 

 three or four weeks in order to allow bacteria, which are invariably 

 present, to undergo dissolution. At the end of this time the glycerinated 

 pulp is thoroughly titrated in specially constructed triturating machines, 

 and put up in small capillary tubes, which are sealed, or "vaccine 

 points" may be prepared. If properly preserved in sealed tubes in 

 a dark, cool place the virus should remain active for at least three months. 

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