462 DISEASES OF SENSATION. SECT. XXXIII. a. 



From thefe cafes I contend, that the contagious 

 matter of thefe difeafes does nor affect the confuta- 

 tion by a fermentation, or chemical change of the 

 blood, becaufe then they muft have proceeded toge- 

 ther, and have produced a third fomething, not 

 exactly iimilar to either of them : but that they 

 produce new motions of the cutaneous terminations 

 of the blood- vefie Is, which for a time proceed daily 

 with increafing activity, like forae paroxyfms of fe- 

 ver, till they at length fecrete or form a fimilar 

 poifon by thefe unnatural actions* 



Now as in the meafles one kind of unnatural mo- 

 tion takes place, and in the fmaTl-pox another kind, 

 it is eafy to conceive, that thefe different kinds of 

 morbid motions cannot exift together ; and there- 

 fore, that that which has firft begun will continue 

 till the fyftem becomes habituated to the ftimulus 

 which occafions- it, and has ceafed to be thrown 

 into aclion by it; and then the other kind of ftimu- 

 lus will in its turn produce fever, and new kinds 

 of motions peculiar to itfelf. 



10. On further considering the aclion of conta- 

 gious matter, fince the former part of this work was 

 fent to the prefs; where I have aliened, in Sect., 

 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 Lei- 

 cefterfhire to try r whether the fmall-pox eould be 

 inoculated by ufing the blood of a variolous pati- 

 ent inftead of the matter from the puftules ; as I 

 thought fuch an experiment^ might throw fome light 

 at lead on this interesting fubject. The following, 

 is an extract from his letter ; 



**. March 1 1 r 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 



