DISEASE-GERMS. 259 



tion of Professor Burdon-Sanderson and myself to take an early 

 opportunity of personally obtaining this from Lira, with a view to a 

 careful and thorough testing of his experiments, with every precaution 

 that experience can devise. 



The recent meeting of the Medical Congress has given me the 

 opportunity of personal communication on this subject both with M. 

 Pasteur and M. Chauveau. From the former I learned that his use 

 of the term " vaccination " in connection with his employment of the 

 mitigated virus of " charbon " and " chicken-cholera," as a protective 

 against the malignant forms of those diseases, was intended rather as 

 a compliment to Jenner than as expressive of any belief in the iden- 

 tity of vaccinia and variola. This question, he said, was one which 

 he had not himself investigated, and on which he did not feel himself 

 justified in forming an opinion. But, when I asked him whether he 

 considered it to have been already decided in the negative, and further 

 informed him of the positive evidence afforded by Mr. Badcock's 

 experiments, he expressed himself strongly in favor of regarding the 

 question as still open, to be decided by further researches carried on 

 under the new light afforded by the results of his own recent investi- 

 gations. I found M. Chauveau himself not less willing to admit the 

 force of the strong analogy between the protective agency of the 

 Jennerian and what I may term the Pastorian " vaccination," and not 

 less ready to accept the results of any thorough reinvestigation of 

 the subject. Such a reinvestigation I hope shortly to see carried out 

 at the Brown Institution by the accomplished young successor to Pro- 

 fessor Greenfield, under the superintendence and with the co-opera- 

 tion of Professor Burdon-Sanderson, in whose great knowledge, long 

 experience, and wise judgment, all who know him and his pathological 

 work have the fullest confidence. 



Now, putting altogether on one side the purely scientific interest of 

 this investigation, let us see in what position we shall be, if it should 

 issue in the confirmation of Jenner's view of the fundamental identity 

 of vaccinia and variola, proving cow-pox to be not a disease sui gene- 

 ris, but small-pox modified by passing through the cow. 



In the first place, we shall have the scientific basis for the practice 

 of vaccination, which it has never yet possessed ; for it will be then 

 clear that the protective power of vaccination is exactly the same in 

 kind as it has long been known to be about the same in degree as 

 that of a first attack of small-pox. 



Secondly, the " common-sense " argument in favor of vaccination 

 will be greatly strengthened by the proof that we are not poisoning 

 the blood of our children with a new disease (which some of the most 

 vehement of the anti-vaccinationists maintain to be already destroying 

 the vitality of the nation), but are merely imparting to them in its 

 mildest form a disease which every one is liable, without such protec- 



