Contagious and Epizootic Diseases. 69 



effect on the system, without at any time endangering life 

 by any sudden increase of germs, and their deadly products 

 within the body. 



7th. The inoculated animal may be kept throughout 

 among the uninoculated, or may be sent at once to any part 

 of the country to mingle with other, stock without a shadow 

 of risk to such stock. It carries no living germ. 



8th. Neither the inoculated animal nor its surroundings 

 is in any need of seclusion during the process, as there is no 

 living gefm present which visitors may carry away with 

 them. 



9th. Neither inoculated animals nor their surroundings 

 are in any need of disinfection before contact with suscepti- 

 ble animals can be allowed. 



Drawbacks to the Method of Protection hy Sterilized 

 Virus. 1st. The main objection to the method is the neces- 

 sity of keeping up a constant cultivation of the germs in 

 their virulent form. This must be done eithei- in living 

 animal bodies or by means of culture-fluids and solids out 

 of the body. In either case we must maintain a centre of 

 infection to supply the inoculating material, and there is al- 

 ways the risk that germs escaping from such centres will 

 start new outbreaks of the plague. 



2d. Such cultures must be conducted with the greatest 

 care, as, alike in and out of the animal body, there is always 

 the liability that the germ may change its habit somewhat, 

 lose its potency, and produce an ineffective virus only, lack- 

 ing in either quantity or quality. Even if grown out of the 

 animal body, therefore, a continuous chain of test cases, in 

 inoculated animals, must be kept up to test the eiHcacy of 

 the cultures. This makes the centres for culture extremely 

 dangerous centres of infection. 



3d. Extreme care is requisite in the sterilizing of the virus, 

 as the slightest failure here is fatal to the procedure, and 

 unless the precautions are extreme there is the strongest 



