tion of Professor Burdon-Sanderson and myself to take an early opportunity of personally obtaining this from him, 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 identity 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 investigations. 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 Professor Greenfield, under the superintendence and with the co-operation 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 generis, 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-
