INTRODUCTOKY NOTE. xiii 



without. On such occasions a reply, in the strict sense 

 affirmed by William Budd, was always at hand ; for I 

 was able to adduce cases of solitary mushrooms, found 

 upon out of the way Alpine slopes, to which the 

 evidence would apply with greater force than to the 

 cases on which the physicians referred to based their 

 conclusions. With the atmosphere as a vehicle of 

 universal intercommunication, it is hard to see any 

 just warrant for the reliance of medical men upon the 

 negative evidence stigmatized by Budd as valueless. 

 It is, however, evidence by which many physicians are 

 still influenced, and the etfects of which it will 

 probably require a generation of doctors, brought up 

 under other conditions of culture and of practice, to 

 wholly sweep away. 



These conditions are growing up around us, and 

 their influence will be all-pervading before long. Never 

 before was medicine manned and officered as it is now. 

 To name here the workers at present engaged in the 

 investigation of communicable diseases would be to 

 extend beyond all reasonable limits this Introductory 

 Note. On the old Baconian lines of observation and 

 experiment the work is carried on. The intercommuni- 

 cation of scientific thought plays here a most important 

 part. It will probably have been noticed, that while 

 physiologists and physicians in England and elsewhere 

 were drawing copiously from the store of facts furnished 

 by the researches of Pasteur, that admirable investigator 

 long kept himself clear of physiology and medicine. 

 There is, indeed, reason to believe that he was spurred 

 on to his most recent achievements by the papers of 



