SECT. XXXIII. 2. 10. OF SENSATION. 315 



into any diforder. At the fame time both the meafles and fmall- 

 pox feem to have been rendered milder. Does not this give an 

 idea, that if they were both inoculated at the fame time, that 

 neither of them might affeft the patient ? 



From thefe cafes I contend, that the contagious matter of 

 thefe difeafes does not affe<ft the conftitution by a fermentation, 

 or chemical change of the blood, becaufethen they mud have 

 proceeded together, and have produced a third fomething, not 

 exactly fimilar to either of them ; but that they produce new- 

 motions of the cutaneous terminations of the blood veflels, 

 which for a time proceed daily with increafing aftiviry, like 

 fome paroxyfms of fever, till they at length fecrete or form a 

 fimiiar poifon by thefe unnatural adlions. 



Now as in the meafles one kind of unnatural motion takes 

 place, and in the fmall-pox another kind, it is eafy to conceive, 

 that thefe different kinds of morbid motions cannot exift togeth- 

 er ; and therefore, that that which has firft begun will continue 

 till the fyftem becomes habituated to the (limulus which occa- 

 fions it, and has ceafed to be thrown into aftion by it ; and then 

 the other kind of ftimulus will in its turn produce fever, and 

 new kinds of motions peculiar to itfelf. 



10. On further considering th^aftion of contagious matter, 

 fince the former part of this work was fent to the prefs ; where 

 I have afferted, in Seft. XXII. 4. 3. that it is probable, that the 

 variolous matter is diffufed through the blood ; I prevailed on 

 my friend Mr. Power, furgeon at Bofworth, in Leicefterfhire, to 

 try, whether the fmali-pox could be 'inoculated by ufing the 

 blood of a variolous patient inftead of the matter from the 

 puftules ; as I thought fuch an experiment might throw fome 

 light at lead on this interefting fubjedt. The following is an 

 extraft from his letter : 



"March n, 1793 I inoculated two children, who had not 

 had the fmall-pox, with blood ; which was taken from a patient 

 on the fecond day after the eruption commenced, and before it 

 was completed, And at the fame time I inoculated myfelf with 

 blood from the fame perfon, in order to compare the appearance, 

 which might arife in a perfon liable to receive the infection, and 

 in one not liable to receive it. On the fame day I inoculated 

 from other children liable to receive the infection with blood 

 taken from another perfon on the fourth day after the com- 

 mencement of the eruption. The patients from whom the blood 

 was taken had the difeafe mildly, but had the moil puftules of 

 any I could feletl from twenty inoculated patients ; and as 

 much of the blood was infmuated under the cuticle, as I could 

 introduce by elevating the fkin without drawing blood , and 



three 



