728 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



should be carefully cleansed with disinfectant solutions at frequent 

 intervals. 



After the heifers are prepared for the work, they are inoculated with 

 the seed virus. The animal under treatment is placed on a special 

 operating table, the ventral surface of the body is shaved and cleansed, 

 and, with a sterile instrument, is scarified in parallel straight lines over 

 the greater portion of the abdomen and inner surface of the flanks. 

 The stock virus or "seed" is inoculated in the scarified areas and the 

 animal is released and placed in the propagating room. During the 

 process of propagation of the vaccine all possible precautionary meas- 

 ures should be used to avoid the introduction of contaminating bacteria. 

 It is important that an attendant be constantly present, day and night, 

 whose duty it is to remove instantly all dirt and faeces and keep the 

 room as clean and free from microbial contamination as possible. 



At the expiration of from seven to nine days, characteristic vesicles 

 will have developed on the inoculated areas. These are filled with a 

 thick, sticky, purulent material. At this time the animal is removed to 

 the operating table, the field of operation is washed with sterile water 

 and the contents of the vesicles removed with a sterile curette. Accord- 

 ing to regulations of the Federal Government all animals used in this 

 work must be slaughtered before the vaccine is removed and later 

 submitted to careful autopsy. After removing the pulp, or vaccine, 

 the material is handled under aseptic precautions and mixed with 

 about 50 per cent glycerin, which serves as a preservative. Small 

 portions of the material are then inoculated into guinea-pigs for safety 

 tests and the product is placed in the refrigerator. Under the in- 

 fluence of the glycerin extraneous microbial contamination gradually 

 disappears. Potency tests of the vaccine are conducted by the cutane- 

 ous application of the vaccine on calves, rabbits or on slightly scarified, 

 scrotal surfaces of guinea-pigs. In addition to the safety and potency 

 tests, inoculations are made into culture media which are placed under 

 both aerobic and anaerobic conditions to insure the absence of harmful 

 bacteria. For the detection of the presence of B. tetani the product is 

 submitted to a special test by transferring i c.c. into a quantity of 

 glucose beef bouillon or other special culture media, placing the 

 culture under anaerobic conditions and incubating at body-temperature 

 for about ten days. After the incubation any resulting growth is 

 removed by filtration and the filtrate is injected into guinea-pigs. 



