iZ6 DISEASES Sect. XXXII. 3. 2. 



•stmcfphcre of heat, in which all things are immerfed, and the 

 other from the internal combinations of the particles, which 

 form the various fluids, which are produced in the extenfive 

 fyftems of the glands. When either the external heat, which 

 iurrounds us, or the internal production of it, becomes lefTened 

 to a certain degree, the pain of cold is perceived. 



This pain of cold is experienced mod fenfibly by our teeth,, 

 when ice is held in the mouth ; or by our whole fyftem after 

 having been previouily accuflomed to much warmth. It is 

 probable, that this pain does not arife from the mechanical or 

 chemical effects of a deficiency of heat -, but that, like the or- 

 gans of fenfe by which we perceive hunger and third, this fenfe 

 of heat fuiFers pain, when the ftimulus of its objectis wanting 

 to excite the irritative motions of the organ ; that is, when the 

 fenforial power becomes too much accumulated in the quiefcent 

 fibres. See Sect.. XII. 5.3. For as the periftaltic motions of 

 the ftomach are lefTened, when the pain of hunger is great, fo 

 the action of the cutaneous capillaries are lefTened during the 

 pain of cold ; as appears by the palenefs of the fkin, as explain- 

 ed in Sect. XIV. 6. on the production of ideas. 



The pain in the fmall of the back and forehead in the cold 

 fits of the ague, in nervous hemicrania, and in hyfteric parox- 

 yfms, when all the irritative motions are much impaired, feems 

 to arife from this caufe ; the veffels of thefe membranes ■ 

 muicles become torpid by their irritative affociations with other 

 pasts of the body, and thence produce lefs of their accuftom* 

 fecretions, and in confeqaence lefs heat is evolved, and they 

 experience the pain of cold ; which coklnefs may often be felt 

 by the hand applied upon the affected part. 



2. The importance of a greater or lefs deduction of heat 

 from the fyitem will be more eafy to comprehend, if v/c firlt 



■ifider the great expenfe of fenforial power ufed in carrying 

 on the vital motions j that is, which circulates, abforbs, fecretes, 



rates, and elaborates the whole mafs of fluids with unceafing 

 afhduity. The fenforial , r # or fpirit of animation, ufed in 

 giving perpetual and itrong motion to the heart, which over- 

 ciatticity and vis tnerthe of the whole arterial fyftem ; 

 next the expenfe of fenforial power in moving with great force 

 and velocity the innumerable trunks and ramifications of the 

 arterial fyftem ; the exnenfe of fenforial power in circulating' 

 the whole mafs of blood through the long and intricate intor- 

 tions of the very fine veflels, which compofe the glands anil 

 capillaries ; then the expenfe of fenforial power in the exer- 

 tions of the abforbent extremities of all the lacteals, and of all 

 the lymphatics, winch open their mouths on the external fur- 

 face 



