VACCINATION. 



It continues out for a day or two, and then begins to 

 fade, fometimes forming two or three concentric circles. 



After the areola is formed, the veficle begins to decline. 

 The centre tirll turns brown, and the whole gradually 

 changes into a hard fmooth fcab, of a very dark mahogany 

 colour. This dry cruft ufually drops off about the end of 

 the third week, leaving a permanent circular cicatrix, about 

 five lines in diameter, and a little depreffed ; the furface 

 being marked with very minute pits, or indentations, de- 

 noting the number of cells of which the veficle had been 

 compofed. 



f^arietles in the Progrejs and Appearance of the vaccine 

 Veficle, not preventing the Succefs of Vaccination. — The firft. 

 appearance is feldom earlier, but often later, than has been 

 defcribed. In fome rare inftances, the veficle commences 

 even a fortnight or three weeks after vaccination ; and if the 

 proigrefs is then regular, it is equally efficacious. 



When the veficle is ruptured at an early period, if the 

 progrefs continue regular, fuccefs is not prevented ; nor is 

 It when the cruft of a regular veficle is rubbed off in the 

 decline of the difeafe, though ulceration Ihould enfue. 



Of irregular and imperfeU Vefichs and Puflules, •which are 



not to be depended upon In thefe deviations, there is ufually 



a premature itching, irritation, inflammation, vefication, 

 or fuppuration ; or the progrefs of the veficle is too rapid, 

 its texture foft, its edge not well defined, its centre ele- 

 vated, and the contents difcoloured or purulent ; or, inftead 

 of a proper areola, a premature efflorefcence of a dulky 

 purple hue takes place, and the fcab is of a light brown or 

 amber colour. 



The inegular veficle or puftule is more liable to be 

 broken than the other, both from its more pointed form 

 and fofter texture, and alfo from its being ufually fo irri- 

 table as to provoke fcratching. When broken, or even 

 without this happening, ulceration often enfues. 



A veficle, apparently regular at firft, fometimes does not 

 augment to the proper fize, but dies away without com- 

 pleting the regular procefs. This ufually leaves no cica- 

 trix, or one which is almoil imperceptible. 



When thefe, or any other confiderable deviations from the 

 regular courfe of the difeafe, take place, no dependence 

 can be placed upon the operation, and vaccination (hould be 

 repeated. 



Probable Caufes of irregular Vejicles and Pujfules. — Thefe 

 accidents may be occalioned by matter or lymph being 

 taken from an irregular veficle or puftule at any period, or 

 from a regular veficle, at too late a period ; or by lymph, 

 though originally pure, which has been injured by long 

 keeping, by heat, or otherwife. Or it may be caufed by 

 performing the operation with a rufty or unclean lancet, or 

 in a rude manner, or by deftroying the veficle at an early 

 ftage, and thereby exciting too much inflammation, or in- 

 terrupting the regular progrefs of the difeafe. Herpetic 

 eruptions, and other cutaneous affeftions, have alfo been 

 fuppofed to be the caufe of thefe irregularities ; and occa- 

 fionally to prevent the vaccine lymph having any efFeft. 



As Dr. Bateman obferves, there are two caufes for 

 thefe imperfeA inoculations : " the one is the infertion of 

 effete or corrupted virus ; and the other the prefence of cer- 

 tain cutaneous eruptions, acute and chronic. 



" The lymph of the vaccine veficle becomes altered in its 

 qualities, foon after the appearance of the inflamed areola ; 

 fo that if it be taken for the purpofes of inoculation after 

 the twelfth day, it frequently fails to produce any efFeft 

 whatever ; and, in fome cafes, it fuddenly excites a puftule, 

 or ulceration ; in others, an irregular veficle ; and, in others, 

 eryfipelas. If taken when fcabs are formed over the 



veficle, (as in the cafe of puftules of fmall-pox,) the vlrw 

 is occafionally fo putrefcent and acrid, that it excites the 

 fame violent and fatal difeafe which arifes from flight 

 wounds, received in diffefting putrid bodies. 



" Agam, the lymph, although taken from a perfeft 

 veficle, on the fixth, fevenfli, or eighth day, may be fo 

 injured, before its appHcation, by heat, expofure to the 

 air, moifture, ruft, and other caufes, as to be rendered in- 

 capable of exciting the true difeafe. 



" The mcft frequent caufe of thefe imperfeftions, how- 

 ever, feems to be the prefence of chronic cutaneous erup- 

 tions, or the concurrence of eruptive fevers, or even of 

 other febrile difeafes. The chronic cutaneous difeafes, 

 which fometimes impede the formation of the genuine vac- 

 cine veficle, have been defcribed by Dr. Jenner under the 

 ordinary indefinite term herpes and tinea capitis. In the 

 more accurate phrafeology of Dr. Willan, they are herpes, 

 (including the fhingles and veficular ring-worm,) pforiafis, 

 and impetigo (the dry and humid tetter) ; the hchen, and 

 moft frequently the varieties of porrigo, comprifing the 

 contagious eruptions denominated by authors crujla laSea, 

 area, achores, and favi. Dr. Willan thinks that the itch 

 and prurigo hkewife have the fame influence. 



" Of the interference of eruptive fevers, meafles, fcarlet 

 fever, and chicken-pox, with the progrefs of the vaccine 

 veficle, when they occur foon after vaccination, numerous 

 inftances have been recorded. The fufpenfwn of its pro- 

 grefs, indeed, would be expefted, under fuch circumftances, 

 from the known fafts refpefting the reciprocal aftion of thefe 

 contagious fevers on each other. But the aftion of the vac- 

 cine virus is not only fufpended by thefe fevers, fo that the 

 veficle is very flow in its progrefs, and the areola not formed 

 till after the fourteenth day, or later, and fometimes not at all ; 

 but it is occafionally rendered altogether inefficient. Even 

 typhous fever, and the influenza, have been obferved to 

 produce a fimilar interruption in the progrefs of vaccination. 



" Finally, the veficle without an areola, takes place if the 

 perfon inoculated have previouQy received the infeftion of 

 fmall-pox, or if he be affefted with fome other contagious 

 difeafe during the progrefs of vaccination. 



" Other irregularities may probably have occurred. At 

 all events, though the conilitution is fometimes fully fe- 

 cured from the infeftion of fmall-pox, even by the irregular 

 veficles ; yet as it is more commonly but imperfeftly 

 guarded by fuch veficles, the propriety of Dr. Jenner's cau- 

 tion is obvious, that, when a deviation arifes, of whatever 

 kind it may be, common prudence points out the neceffity 

 of re-inoculation." See Bateman's Synopfis of Cutaneous 

 Difeafes, p. 219 — 221. edit. 3. 



The Methods of taking Vaccine Lymph for Vaccination. — 

 The lymph of a regular veficle is efficacious from the time 

 it is fecreted, till the areola begins to fpread. It may, 

 therefore, commonly be taken till the ninth day ; but not 

 after the areola is fuUy formed. 



The lymph is to be taken by fmall fuperficial punftures 

 made in the veficle, with the point of a lancet introduced 

 horizontally. Time fliould be allowed for the liquid to 

 exude, which will form fmall pellucid drops. When re- 

 quifite, a very flight preffure may be cautioufly apphed with 

 the flat furface of the lancet. Great delicacy is requifite in 

 this operation ; for if the veficle is rudely treated, or too 

 much opened, inflammation and ulceration may enfue. 



Lymph intended to be ufed immediately, or in a few 

 days, may be received on 3 lancet ; but this is an improper 

 initrument for preferving it longer ; for the lymph foon 

 rufts the lancet, and it is then liable to be inefficacious, or 

 injurious. Quills and tooth-picks fucceed j but fmall bits 

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