Ill PASTEUPv AND HYDROPHOBIA 137 



liealthy men that they have started on the path 

 leading to hydrophobia, and then treat six by a 

 remedial process, and leave six without such treat- 

 ment, in order to see whether the remedial process 

 has an effect or not. *Tliis is the kind of diffi- 

 culty which is met with in all attempts to take a 

 step forward in medical treatment. Nevertheless, 

 although such definite experimental arrangement of 

 the subject of inquiry is not possible where human 

 beinpfs are concerned, there is another method — 

 extremely laborious, and less decisive in the results 

 which it affords — by which a more or less probable 

 conclusion may be arrived at in regard to the effect 

 of treatment of diseased human beings. This method 

 consists in bringing together for experimental treat- 

 ment a very large number — some thousands — of cases 

 in which the disease under investigation has, independ- 

 ently of the experimenter, been acquired, or is supposed 

 to have been acquired, and then to compare the pro- 

 portion of cases of recovery obtained under the new 

 treatment with the proportion of recoveries in cases 

 not subjected to this treatment. 



Hydrophobia presents peculiar difficulties in the 

 application of this method, and the treatment which 

 M. Pasteur is now testing is also one which in its 

 essence renders the statistical method difficult of 

 application. M. Pasteur's treatment has to be applied 

 hefore the definite symptoms of hydrophobia have 

 developed in the patient. Accordingly, there is no 

 certain indication in the patient himself that he has 

 really been infected by the virus of rabies ; the infer- 



