148 PRACTICE OF PHYSIC. 



very commonly combined with other circumstances which are 

 very certainly exanthematic. If only buboes occurred in the 

 plague, we might entertain these doubts ; but as, at the same 

 time, anthraces and other symptoms of Exanthema are pre- 

 sent, we must presume that both arise from one common 

 contagion, and that the bubo is only one variety of this deter- 

 mination. 



" I go on to observe, that Exanthemata are, especially in 

 their several genera, distinguished by the nature of the erup- 

 tion. The matter determined to the skin and effused there, is 

 manifestly of three kinds : first, it is serum, which is naturally 

 and spontaneously changed into pus, as is the case in smallpox ; 

 secondly, the serum appears at first, but is not naturally and 

 spontaneously changed into pus ; such is the case in Varicella, 

 and in Pemphigus so far as admitted among the Exanthemata : 

 it is a very rare appearance that in these diseases there is any 

 approach towards the change into pus. A third case is, where 

 the matter is not collected into any sensible portions, so that we 

 could give it the appellation of serum : where, indeed, it is not 

 manifestly fluid, but appears in a number of very small papillae ; 

 but as in most cases these end in desquamation, we have rea- 

 son to suspect that a matter was effused, which, either in conse- 

 quence of exudation affords these scales, or, as we know in 

 other cases, separates . the cuticle, and makes it fall off. We 

 cannot say any thing positive with regard to the matter here 

 effused ; but if it is effused, it is by certain circumstances divid- 

 ed into small and insensible portions, thus distinguishing, for 

 instance, Scarlatina from other Exanthemata. 



" Fourthly, A part of the generic character of Exanthemata 

 may, in some cases at least, be taken from the part which they 

 occupy, from the limits they have, and from the extent they ad- 

 mit of. Thus, Erysipelas, if considered as an Exanthema, is 

 distinguished as solitaria by Linnaeus, and properly, for thereby 

 it differs from almost all the others, whose topical affections are 

 more numerous. With regard to those which are more numer- 

 ous, a curious circumstance is this, that most of them generally 

 appear more on the face than on any other part of the body ; 

 while there is one eruption that has been commonly reckoned 

 among Exanthemata, viz. the miliary eruption, which, although 



