PREVENTIVE TREATMENT 



167 



Pasteur was enabled to obtain the virus in all 

 degrees of activity : he could always keep going 

 one or more series of cords, of known and exactly 

 graduated strengths, according to the length of 

 time they had been dried — ranging from absolute 

 non-virulence through every shade of virulence. 



And, as with fowl-cholera and anthrax, so with 

 rabies ; a virus which has been attenuated till it 

 has been rendered innocuous, can yet confer im- 

 munity against its more virulent forms : just as 

 vaccination can protect against small-pox. A man, 

 bitten by a rabid animal, has at least some weeks 

 of respite before the disease can break out ; and, 

 during that time of respite, he can be immunised 

 against the disease, while it is still dormant : he 

 begins with a dose of virus attenuated past all 

 power of doing harm, and advances day by day 

 to more active doses, guarded each day by the dose 

 of the day before, till he has manufactured within 

 himself enough antitoxin to make him proof against 

 any outbreak of the disease. 



The cords used for treatment are removed from 

 the bodies of the rabbits, by an aseptic method, 

 and are cut into lengths and hung in glass jars, 

 with some chloride of calcium in them, for drying. 

 The jars are dated, and then kept in glass cases in 

 a dark room at a constant temperature. To make 

 sure that the cords are aseptic, a small portion of 

 each cord is sown on nutrient jelly in a test-tube, 

 and watched, to see that no bacteria occur in the 

 tube. For each injection, a certain small quantity 

 of cord is rubbed-up in sterilised fluid ; and these 



