What you say about the confusion existing in the minds of the medical profession as shown by medical text-books regarding the origin of vaccine is entirely true. No one seems to know positively the exact nature of this product. It would seem to us, however, that the theory that cowpox is but modified smallpox, is the most tenable one. Particularly does this seem true in view of the facts reported by Dr. Monckton Copeman, Director of the Government Vaccine work in London, that he had been able to take smallpox virus, transmit it to monkeys, from monkeys to heifers, and from heifers to man, the resulting vaccination on the human subject being identically the same as that produced by vaccine as ordinarily prepared. Furthermore it was shown that the persons vaccinated with this vaccine, when exposed to smallpox, were immune. In other words, the chain of evidence seems very complete, that by properly transferring the smallpox virus from man to animals of different species it became so modified in the transmission that, when applied to heifers, it produced typical vaccinia, and was found to fill every requirement as a means of protecting against smallpox when applied to unimmunized children. On theoretical grounds it seems to us that this is a very plausible explanation of the origin of vaccinia. During Jenner’s time smallpox was very prevalent and nothing could be more natural than for persons recovering from smallpox to transmit the disease to the udders of cows, producing an infection which, on account of the difference in the species of the animal, modified the smallpox virus. Regretting that we are unable to state more positively the exact relation between the two diseases and the origin of the seed as used by manufacturers, we remain, Very sincerely yours, (Signed) PARKE, DAVIS & CO. THE DISPUTED OR UNKNOWN ORIGIN AND NATURE OF MODERN VACCINE VIRUS EMPHASIZED. LETTER FROM PARKE, DAVIS & CO., ONE OF THE LARGEST MAKERS OF VIRUS IN THE U. S. This letter, like the preceding one, frankly admits the doubt, ignorance and confusion as to the origin of vaccine virus, and the practically unknown origin and nature of the seed virus used by manufacturers, except that it most probably originates in human smallpox, pure and simple. This letter is given in full on the left and speaks clearly for itself and is worth reading carefully on this most important point as it shows the crude, unknown and unscientific basis of all bovine vaccination which is proved out of the mouths of the arch-vaccinators themselves. See also page 82. AN ENGLISH SAILOR LOSES HIS ARM FROM COWPOX VACCINATION [Illustration: FIG. 14. Before Vaccination] [Illustration: FIG. 15. After Vaccination] CASE OF HENRY PLANT