Jenner's claim to priority of discovery has been subject to dispute, and the objection seems to be, in some particulars, founded on fact. There appears to be but little doubt that a farmer by the name of Benjamin Jesty, living in Downshay, Isle of Purbeck, was the first who is known to have practised vaccination. He inoculated his wife and two sons with matter taken from cows suffering from cowpox. All were affected. His wife s arm became very much inflamed and produced no small alarm in the family and no small sensation among his neighbors. Fifteen years after (1789), the sons, together with other persons, were inoculated with matter taken from a smallpox case, as was then the custom, to protect against the smallpox contracted in the ordinary way. None of those previously vaccinated with cowpox be came ill with inoculated smallpox, whereas others inoculated passed through the several stages of the disease. There was a great pre judice against Jesty's experiments, and the peo ple would have none of them. Jesty's remark was that for his part he "preferred taking in fection from an innocuous animal like the cow, subject to so few disorders, than to take it from a human body liable to so many diseases; and that he had experience on his side, as casual smallpox was not attended with dangers like the variolous infection, and that besides there appeared to him little risk in introducing into the human constitution matter from the cow, as we already, without danger, eat the flesh, drink the milk and cover ourselves with the skin of this innocuous animal." Also, there is recorded that a Holsteiner, by the name of Plett, inoculated three children with matter taken from the udder of a cow suffering with °cowpox° using his pocket knife to make the insertion. All the inoculations were successful ; later when smallpox appeared all had the dis ei.se but these children. On an examination of Jenner's papers, it seems that he makes no claim as to priority, simply recording his own obser vations and giving in detail his experiments to support the theory that smallpox can be pre vented by vaccination. He also proves that the prevailing opinion shared by the milkers, that cowpox contracted by them was protective against smallpox, was founded on fact. Had it not been for Jenner's brilliant, painstaking work, replete with accurate observations, in all probability Jesty's inoculations would have been lost, and a long time might have elapsed before the beneficent discovery of vaccination would have become known. The principal conclusions of Jenner's discovery may be summarized thus: (1) That vaccinia or cowpox casually induced in man renders him insusceptible to smallpox.
(2) Only the specific agent of vaccinia or small pox, and no other eruptive disease of the cow, has this power. (3) Cowpox may be induced at will from cow to man. (4) That engrafted cow pox may be continued indefinitely from man to man, conferring on each in succession insus ceptibility to smallpox, the same as could be produced by inoculation of the virus direct from the cow to man.
Origin and Distribution of Vaccinia or Vaccinia in the cow is an eruptive vesicular disease, usually occurring on the teats and udder, sometimes on the muzzle and mucous membrane of the mouth and nose. It may occur in isolated instances, sometimes affecting one or only a few of the herd; at other times it may attack the whole herd. Its origin among cattle has been the subject of much dispute, some claiming that it always occurs spontaneously, citing as examples those isolated cases not in frequently met with, while others claim with equal positiveness that before an animal can have the disease it must contract it from some other source. The latter contention is more probable, as there is no instance of an analogy to the former existing in other infectious dis eases. The contagion, therefore, must be trans
mitted in some manner to the animal, and its source must be either an animal or man having this disease. No other conclusion seems pos sible. It sometimes is met with occurring in horses, and is known as the °grease.° Jenner demonstrated that the grease° and cow pox were one and the same malady, and that matter taken from the horse could be trans mitted to the cow, causing an inflammation and symptoms identical with cowpox and, moreover, protecting equally as well against smallpox as does vaccinia. Bouley of Alfort has also made a study of the disease of horses, to gether with cowpox, and concludes that they are one and the same disease. In further support of the theory that the disease is transmitted to the bovine species largely through human agencies, it is a well-known fact that it is more frequently met with among milch cows than in either the heifers or males of the same herd. The reason for this is that the cowpox virus is transferred from cow to cow by means of the milkers' hands. The prevalence of cowpox appears to be in some way influenced by the seasons, more cases having been reported occurring during the spring months than at other times of the year. Suckling calves are also quite susceptible. It cannot be said however, that vaccinia affects only cows, or tie young calf, as all animals of the bovine species can be readily inoculated with the virus and the lesions caused by such inocu lations are identical with those occurring taneously." Jenner supplied many countries in his time with vaccine virus, originally from the cow, and subsequently propagated from arm to arm. The American stock of vaccine virus was introduced into the United States in either 1801 or 1802 by Waterhouse in Boston, and Hosack in New York, and at the same time in the Southern States through the interest of Presi dent Jefferson. Some of the strains were propagated for a long time by the arm-to-arm method. In Europe a strain of the original, re ceived from Jenner in 1802, was still being propagated at Vienna as late as the 80's. The celebrated Beauagency stock, originating from a °spontaneous') case of cowpox in 1864, has furnished many strains. This was largely employed in France, Belgium, Germany and England, and was introduced in the United States in 1870 by Dr. Martin of Boston, just before the original was lost, during the siege of Paris. It is not known whether this par ticular strain is in existence at the present time. Many strains became so attenuated that they failed to cause the typical lesions and character istic symptoms of vaccinia, and, most important of all, their protective property was very slight, if it existed at all. The result of employing such virus during what may be termed a pan demic prevalence of smallpox was that many persons who had been previously inoculated with it contracted smallpox. This made it necessary to abandon these weak strains for others of greater strength. Such experiences are not un common in the history of the vaccine virus, even as far hack as Jenner's time. Jenner emphasized this point of the attenuation of the virus, and regarded it necessary to renew the strain from cases of cowpox wherever possible. Retro vaccination, or inoculation of the cow with human virus, was often resorted to for the purpose of reviving the strain. The number of cases of natural cowpox have become ex ceedingly rare during the last half of the past century, only a few instances being reported from year to year, whereas in Jenner's time the disease was very prevalent. The fewness of the cases may he accounted for by the rarity of cases of smallpox at the present time, as compared with those of the past.