VACCINATION. 



patient being conftitutionally affefted with the cow-pox, and 

 the following obfervations upon this important fubjeft merit 

 particular attention. " I recollefted (fays he) fome experi- 

 ments which had been made with regard to the inoculation of 

 fmall-pox. It was found, that if the fame perfon was ino- 

 culated every day, until the fever induced by the firft inocu- 

 lation fupervened, all the other punftures quickly advanced 

 in their progrefs ; and that, in the courfe of a day from the 

 time the fever or general affeftion began, even that punfture 

 which had been laft made, perhaps only twenty-four hours be- 

 fore, equalled in maturity the one firft made, perhaps eight 

 or nine days before, and from which the fever had arifen. 



" In this cafe it appears to me evident, and I think it muft 

 be admitted by every perfon, that even had no other puftules 

 appeared on the body but thofe occafioned by the repeated 

 inoculations ; nay, had there even been no fever obferved in 

 confequence of the inoculation ; yet as the puflule occa- 

 fioned by the laft punfture had been fuddenly accelerated in 

 its progrefs to maturation, at the time the general or confti- 

 tutional afFeftion (hould have appeared ; this alone was a fuf- 

 ficient proof of the prefence of the variolous aftion in the 

 fyftetri. 



- " Judging again from analogy, I expcfted that the fame 

 thing, which thus happened in the fmall-pox inoculation, 

 might alfo take place in that for the cow-pox ; and the unex- 

 pefted appearance of one or two veficles upon children that 

 I had inoculated, which veficles were quite charafteriftic of 

 the ailmeut, and the appearance of which I could only ac- 

 count for from a fecond and accidental inoculation during 

 the courfe of the difeafe, ftrengthened my hopes. And, 

 certainly, if we find in cow-pox, where the inflamed and 

 hard areola does not take place, at leaft in the regular 

 courfe of that affeftion, until the end of the feventh, or 

 beginnning of the eighth day from inoculation, that a fe- 

 cond inoculation, performed, for example, at the end of the 

 fifth, or beginning of the fixth day, is fo much accelerated 

 in its progrefs, about the time the general affeftion of the 

 fyftem ufually takes place, as to have an areola formed within 

 a few hours, or very fhortly after the firft, and that this 

 areola increafes with the firft, and again fades at nearly the 

 fame time, we muft be ftruck with the fimilarity, and be 

 forcibly led to draw the fame conclufions in this cafe as in the 

 former, refpefting the fmall-pox, viz. that although the 

 inoculated affeftion had appeared very flight, and no fever 

 had been obferved, yet that a certain aftion had been ex- 

 cited in the conftitution. That this was the true conftitu- 

 tional affeftion of cow-pox, may be judged by the accelera- 

 tion of the fecond veficle to a ftate of maturity five days be- 

 fore this could have happened, had there been no confenta- 

 neous general aftion, or change in the fyftem." 



Mr. Bryce next details a feries of experiments, which 

 tend to prove, that if, during the regular progrefs of cow- 

 pox, a fecond inoculation be performed a certain number of 

 days after the firft, the affeftion produced by this fecond 

 inoculation will be accelerated in its progrefs fo as to arrive 

 at maturity, and again fade at nearly the fame time as the 

 affeftion arifing from the firft inoculation ; and that this 

 will take place, although the conftitutional affeftion be fo 

 flight as otherwife to pafs unnoticed. 



From feveral examples related by Mr. Bryce, and a great 

 many other cafes, in which the fecond inoculation was per- 

 formed at different periods of the primary affeftion, it is 

 concluded, that the moft proper time for performing the 

 fecond inoculation, is about the end of the fifth, or begin- 

 ning of the fixth day, from the firft inoculation ; reckoning 

 each day to confift of twenty -four hours. Thus, if the firft 

 inoculation be performed on Wedncfday at noon, the fecond 



inoculation ihould be performed on Monday, at the fame 

 hour, at which time the fifth day is confidered to be finilhed, 

 and the fixth day to begin. If the fecond inoculation be 

 delayed beyond the fixth day, the affeftion produced by it 

 will be very indiftinft, and of ftiort duration ; and if per- 

 formed at an earlier period than the fifth day, the contraft 

 between the progrefs of the two affeftions, with regard to 

 duration, will not be fo great as may be thought neceffary. 



" Thefe obfervations, however, ( fays Mr. Bryce, ) are ap- 

 plicable to thofe cafes only, in which the firft inoculation 

 advances by a perfeftly regular courfe, and in which the 

 areola begins to form about the end of the feventh, or begin- 

 ning of the eighth day ; for in thofe cafes, in which the 

 firft inoculation is from certain caufes accelerated or re- 

 tarded one or two days, as frequently happens, then the 

 fecond inoculation fliould be performed at a more early or 

 late period accordingly. 



" In ftiort, my obfervations on this point lead me to con- 

 clude, that in order to obtain the propofed criterion in the 

 greateft perfeftion, the fecond inoculation fliould be per- 

 formed between thirty-fix and forty-eight hours before the 

 areola of the firft inoculation begins to appear. Tliis is 

 neceffary in order that the fecondary affeftion may have 

 proceeded fome length, and that a fmall veficle, containing 

 virus, may have been formed by it, before the conftitutional 

 aftion from the firft inoculation begins, otherwife no areola, 

 but merely a flight degree of hardnefs will take place from 

 the fecond punfture. 



" As, on the one hand, the acceleration of the fecond 

 inoculation in the manner above-mentioned, is to be re- 

 garded as a certain mark of a conftitutional affeftion in 

 cow-pox, fo, on the other, if it ftiall be found that no fuch 

 acceleration takes place, but that the fecond inoculation 

 proceeds by a flow progrefs througli all the ftages, and has 

 the duration of a primary affeftion, it is to be concluded 

 that no conftitutional aftion has taken place from the firft 

 infertion of the virus ; and when this is the cafe, the fecond 

 inoculation muft be regarded as a primary affeftion, and a 

 third punfture be made according to the plan laid down for 

 condufting the fecond inoculation ; and thus we may go on 

 until the proper teft be obtained, or until we be fatisfied 

 that the conftitution completely refills the aftion of cow- 

 pox." See Bryce's Praftical Obfervations on the Inocula- 

 tion of Cow-pox, edit. 2. 



Many other particulars relating to the fubjeft of vaccina- 

 tion will be found in another place (fee Cow-pox), and we 

 ftiall therefore merely add, that the new praftice is on every 

 account deferring of the confidence and encouragement of 

 the public. The cow-pox is greatly milder than the fmall- 

 pox, even under the moft approved mode of treatment ; 

 being never attended with danger, feldom with ficknefs, and 

 never producing puftules generally over the body, nor 

 indeed any disfigurement of the fl<in, except at the part 

 where the virus has been direftly inferted by the inoculator. 

 The fmall-pox is erne of the moft contagious difeafes to 

 which the human race is fubjeft ; and, when propagated in 

 this way, it is one of the moft fatal. On the other hand, 

 the cow-pox is not at all contagious, and can only be com- 

 municated by the application of the vaccine virus to the 

 part affefted, as happens in the accidental inoculation of the 

 hands of milkers, and the ordinary praftice of vaccination. 



Many hundreds of thoufands have now been vaccinated in 

 thefe kingdoms, and yet there is not on record a fingle une- 

 quivocal inftance of the cow-pox having proved fatal. 

 Correfponding agreeable accounts are alfo received from 

 every part of the civilized world. The weight which this 

 confideration ought to have may be well conceived, when it 



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