HYDROPHOBIA, OR RABIES. 387 



attenuated, then with moderately strong, and finally with, 

 strong, virus, the dog developed an immunity which 

 enabled it to resist the infection of an amount of viru- 

 lent material that would certainly kill an unprotected 

 animal. 



It is remarkable that this thought, which was a theory 

 based upon a broad knowledge, but experience with 

 comparatively few bacteria, should every day find more 

 and more grounds for confirmation as our knowledge 

 of immunity, of toxins, and of antitoxins progresses. 

 What Pasteur did with rabies is what we now do in 

 producing the antitoxin of diphtheria — i. e. gradually 

 accommodate the animal to the poison until its body-cells 

 are able to neutralize or resist it. As the poison cannot 

 be secured outside of the body because the bacilli, micro- 

 cocci, or whatever they may be cannot be secured outside 

 of the body, he does what Behring originally did in diphr 

 theria — introduces attenuated poison-producers — bacilli 

 crippled by heat or drying, and capable of producing only 

 a little poison — accustoms the animal to these, and then to 

 stronger and stronger ones until immunity is established. 



The genius of Pasteur did not cease with the produc- 

 tion of immunity, but, we rejoice to add, extended to the 

 kindred subject of therapy, and has now given us a cure 

 for hydrophobia. 



For the production of a cure in infected cases very 

 much the same treatment is followed as has been der 

 scribed for the production of immunity. The patient 

 must come under observation early. The treatment con- 

 sists of the subcutaneous injection of about 2 grams of 

 an emulsion of a rabbit's spinal cord which had been 

 dried over caustic potash for from seven to ten days. 

 This beginning dose is not increased in size, but each 

 day the emulsion used is from a cord which has not been 

 dried so long, until, when the twenty-fifth day of treat- 

 ment is reached, the patient receives 2 grams of emulsion 

 of spinal cord dried only three days, and is considered 

 immune or cured. 



