ON CLASSIFCATION OP PERSONS EXPOSED TO SMALLPOX. 507 



vaccination which has not produced a well-foveolated, depressed 

 cicatrix, having a fairly well-detined edge, and visible several yards 

 away, is a vaccination wliich has not conferred on the subject all 

 the protection which a primary vaccination is capable of giving ; 

 nevertheless, 1 am content to classify as " good ", scars which show 

 some, although not perfect foveolation, although scientitically they 

 are something less than good, in order not to overstate the case 

 for vaccination. All scars without foveolation— from mere smooth 

 ill-detined cicatricial whitenings of the skin, such as are due to 

 imperfect vaccination by puncture, to the sliarp-cut deep scar 

 with a raised and often livid centre, whicli is the result of 

 ulceration of the vesicle — all these I classify as " bad." 



Note on the Classification of Scars by Area. — Jenner's vaccina- 

 tions from spontaneous cow-pox by puncture would classify but 

 low on any s.^heme hitherto projected or at present possible ; yet 

 their protective effect was such as withstood the severest tests, 

 including inoculation with variolous matter. (An Enquiry, &c.," 

 " Further Observations, &c ," and " A continuation, etc.," repro- 

 duced in facsimile from the 2nd Edition for the Government of 

 New South Wales, 1884.) Marson's statistics have sliown chat 

 the protection conferred by vaccination as now commonly practised 

 is in relation to area as well as to character ; all classifications 

 must, therefore, essentially resemble his. But I venture to suggest 

 that his four categories of area which were possible and proper 

 in his day, because, I suppose, vaccination was then ordinarily 

 done by puncture, are now become inexact and inappropriate. 

 As long as operation by single puncture was in vogue, statement of 

 the number of scars constituted in fact a sufficiently accurate 

 statement of area ; for good vesicles so produced result in scars 

 which usually measure .12 of a square inch, and seldom fall below 

 ,1 ; an observation for which we are indebted to Dr. Burdon- 

 Sanderson, and which I have verified for myself. But the 

 operation by puncture having been superseded (at least among 

 the English) by scarifications, abrasions, or multiple punctures, 

 this auto-mensuration by mere reckoning of the number of scars 

 is no longer possible. Moreover, the area of a scar produced by 

 puncture being no longer familiar, the estimate of larger cicatrices 

 as equivalent to " two, three, or four scars, &c," must be recorded 

 subject to considerable doubt. It appears to me, therefore, that for 

 any such purpose as we are now concerned with, resort to actual 

 measurement has become necessary. Three or four years ago T 

 caused a gauge to be constructed on the lines indicated by Dr. 

 Burdon-Sanderson, in his Vaccination Report, included in the Sixth 

 Report of the Medical Officer to the Privy Council. It consists of 

 a small metal plate having a trapezoidal aperture like the section 

 of a truncated cone. On one longitudinal margin are written at 

 several points the length of imaginary lines necessary to reach 



