ON THE FUNCTIONS OF THE HEART AND ARTERIES* 1Q1 



perhaps lead immediately to a mortification, which is called 

 by the Germans " a cold burning." 



The most usual causes of inflammation appear to be easily These con- 

 reconcilable with these conjectures. Suppose any consider- •'?^^"''^^ ^'^^' 



^■^ •' sistent with 



able part of the body to be affected by cold ; the capillary the common 



vessels will be contracted, and at the same time the tempera- ^^"^^^ »( >"- 

 ~ , . Ml 1 1 1 V. nammation, 



tuire of some parts or their contents will be lowered, from 



both of which causes the resistance will be increased, and 

 the arteries in general will be more or less overcharged : if 

 then any other part of the system be at the same time de- 

 bihtated or overheated, its arteries will be liable to be mor- 

 bidly distended, and an inflammation may thus arise, 

 which may continue till the minute vessels are supported 

 and strengthened, by means of an eff'usion of coagulable 

 lymph. The immediate effect, either of cold or of heat, 

 may also sometimes produce such a degree of debility in any 

 part, as may lay the foundation of a subsequent inflamma- 

 tion : but the first effect of heat in the blood-vessels appears 

 to be the more ready transmission of the blood into the 

 veins, by means of which they become very observably 

 prominent: and cold, which checks the circulation in the 

 cutaneous vessels, probably occasions a livid hue, by retain- 

 ing the blood stagnant longer than usual in the capillary 

 vessels of all kinds. It may be objected, that an obstruc- 

 tion of the motion of the blood through a great artery ought, 

 upon these principles, to produce an inflammation in some 

 distant part: but in this case, the blood will still find its 

 way very copiously into the parts supplied by the artery, 

 by means of some collateral branches, which will always 

 admit a much larger quantity of blood than usually passes 

 through them, whenever a very slight excess of force can be 

 found to carry it on, or when the blood which they contain 

 finds a readier passage than usual, by means of their com- 

 munication with such parts as are now deprived of their 

 natural supply. 



It is difficult to determine, whether blushing is more pro- Blushing, 

 bably eff'ected by a constriction or by a relaxation of the 

 vessels concerned ; it must, however, be chiefly an affection 

 of the smaller vessels, since the larger oues do not contain a 

 sufficient quantity of blood to produce so sudden an effect. 



Perhaps 



