SECT.XXXIIT.2. DISEASES OF SENSATION. 455 



from hunger, third, cold, or inanition, with all 

 thofe pains which are termed nervous. Where thefe 

 pains exift, the motions of the affected part are 

 leilened ; and if inflammation fucceeds, it is in fome 

 diiiant parts ; as coughs are caufed by coldnefs and 

 moifture being long-applied to the feet ; or it is in 

 confequence of the renewal of the flimulus, as of heat 

 or food, which excites our organs into ftronger acti- 

 on aftet their temporary quiefcence ; as kibed heels 

 after walking in fnow. 



4. But when thefe new motions of the vafculaf 

 mufcles are exerted with greater violence, and thefe 

 veffels are either elongated too much or too haftily, 

 a new material is fecreted from their extremities, 

 which is of various kinds according to the pecu- 

 liar animal motions of this new kind of gland, which 

 fecre'es it ; fuch is the pus laudabile or common 

 matter, the variolous matter, venereal matter, ca* 

 tarrhous matter, and many others. 



5. Thefe matters are the product of an animal 

 procefs ; they are fecreted or produced from the 

 blood by certain difeafed motions of the extremities 

 of the blood-vefiels, and are on that account all 

 of them contagious ; for if a portion of any of 

 thefe matters is tranfmitted into the circulation, or 

 perhaps only inferted into the ikin, or beneath 

 the cuticle of an healthy perfon, its flimulus in a 

 certain time produces the fame kind of morbid mo- 

 tions, by which itfelf was produced ; and hence a 

 iimilar kind is generated. See Seel. XXXIX. 6. I. 



6. It is remarkable, that many of thefe contagi- 

 ous matters are capable of producing a fimilar dif- 

 eafe but once ; as the final 1-pox and meafles ; and 

 I fuppofe this is true of all thofe contagious dif- 

 eafes, which are fpontaneoufly cured by nature in a 

 certain time ; for if the body was capable of re- 

 ceiving the difeafe a fecond time, the patient muft 

 perpetually infed himfelf by the very matter, which 



he 



