ERUPTIVE FEVERS. 145 



tions, and to direct our further observations; without it the 

 matter would have remained in the uncertainty, confusion, and 

 obscurity in which it has continued for ages past. 



" In the first place, we must attend to the character of the 

 order. I find it difficult in this character to distinguish Ex- 

 anthemata from the two preceding orders Febres and Phleg- 

 masise. We may seem to distinguish them from Fevers, by 

 this, that they are steadily and constantly attended by a topi- 

 cal affection, but we shall find this in some cases doubtful. 

 I find that there are Phlegmasiae which seemingly arise at 

 some distance of time after the symptoms of fever are formed ; 

 but, on the other hand, there are Exanthemata which arise 

 before the fever, or at least along with it. These are the 

 doubts which still remain with regard to the genera compre- 

 hended in this order. But I can do no better than take what is 

 the most common case ; and suppose that in the Phlegmasiae 

 there is, from the beginning, a topical inflammation, which 

 generally is not the consequence, but the cause of the fever : 

 and, upon the other hand, of the Exanthemata we would in gene- 

 ral give the idea, that their cause is not topical, and does not 

 act topically, but that there is a particular matter, or what- 

 ever you please to call it, diffused over the system, and ap- 

 plied to it more generally; and that, in consequence of an 

 action upon the nervous system analogous to that of the cause 

 of fever, a fever is produced, and only in consequence of that 

 fever an eruption. 



" It is difficult, however, to decide, according to this view, 

 what genera are properly comprehended under the order of 

 Exanthemata ; we shall find presently that, with regard to seve- 

 ral, the matter is very doubtful. We can point out one clear 

 case of Exanthema ; for example, where we certainly know that 

 a contagious matter is often introduced by art. We observe 

 that this first produces a fever, and that only after a certain 

 determined duration of the fever, an eruption is produced, 

 steadily and constantly of one particular kind. In this circum- 

 stance, nobody doubts that this is an Exanthema, to be dis- 

 tinguished equally on the one hand from fever, and on the 

 other from phlegmasioe. But it may happen that there is, or at 

 least that we know of, no specific contagion ; or supposing that 



VOL. II. K 



