Ill PASTEUR AND HYDROPHOBIA 145 



same time lie inoculated also a rabbit. When the 

 second rabbit went mad and died, the dogs were again 

 inoculated from it, and a third rabbit was also inocu- 

 lated from it. When this rabbit died the process was 

 repeated with the dogs and with a fourth rabbit, and 

 so on until the virus had become (as above stated to 

 be the case) greatly increased in activity, its incuba- 

 tion period being reduced to eight days. The dogs 

 were not rendered rabid by the first inoculations ; they 

 certainly would have been by the last, had they not 

 undergone the earlier. The harmless virus rendered 

 the dogs insusceptible to the rabies-producing quality 

 of the second dose introduced, the second did the same 

 for the third, the third for the fourth, and so on until 

 the dogs were able to withstand the strono-est virus. 



It would seem that this method of using a gradu- 

 ated series of poisons was not intentional on Pasteur's 

 part at first, but merely arose from the convenience of 

 the arrangement, since the effect of the previous in- 

 oculation could be tested and a new inoculation to act 

 as a preventive could be made at one and the same 

 time. Nevertheless, Pasteur has retained for reasons^ 

 which it is possible to imagine but have not been given 

 as yet by him, this method of repeated doses of gradu- 

 ally increasing strength in his subsequent treatment. 



In 1884 a Commission was appointed at M. 

 Pasteur's request by the Minister of Public Instruction 

 to examine the results so far obtained by him in regard 

 to a treatment by which dogs could be rendered re- 

 fractory to rabies. The Commission comprised some 

 of the ablest physiologists in France ; it consisted of 



L 



