Reverting to Jenner’s suppression of the origin of cowpox in horsegrease, it may be suggested that he had changed his mind: but he had not changed his mind. As observed, various attempts were made to inoculate cows with horsegrease, and that these attempts were failures; but subsequent attempts were successful. Tanner, a veterinarian, of Rockhampton, Gloucestershire, succeeded to Jenner’s complete satisfaction. Dr. Loy of Whitby dispensed with the cow altogether, and inoculated with horsegrease, or horsepox, producing vesicles identical with those of cowpox. The great success, however, in this line was reserved for Sacco of Milan. From the hand of a coachman poisoned with horsegrease he inoculated nine children, and from the virus thus engendered operated on every side. Writing to Jenner in 1803, Sacco said--“It is now admitted and settled that grease is the cause of vaccine, and we cannot too soon alter the designation to equine.” De Carro of Vienna received this equine from Sacco, and used it so freely and successfully among the Viennese, that, in his own words, it became impossible to say which of the citizens were equinated and which vaccinated. What did Jenner make of these confirmations? He was adjudged mistaken in asserting that the cowpox good against smallpox was derived from horsegrease. Did he appeal with triumph to the evidence of Sacco, and say, “You thought me wrong, but see, I was right!” Not he. He kept silence. He consented to be treated as in error. He stood by and allowed cowpox to be used in which he had no confidence whatever. Nay more. He consented to be rewarded and honoured as the discoverer of a pox (which he did not discover) in which he was without faith, and had at the outset of his career expressly rejected and condemned. He recognised that it was expedient that the connection between horsegrease and cowpox should be denied. He had his bill to settle with the English people, and it was not for him to make difficulties. When, however, he had obtained all he could expect from public favour, and had got clear of London and the oppression of its savants, why then he resumed the expression of his original opinion; and still further, like Sacco of Milan, he dispensed with the cow, and inoculated straight from the horse. He supplied the National Vaccine Establishment with horse virus; he sent it to Edinburgh; he distributed it among his medical acquaintances; he described it as “the true and genuine life-preserving fluid.” What more need I say? Such was Jenner; such were his tactics; and whoever assumes his defence will assume a task in which he is not to be envied. WHICH SHALL IT BE?