INFLAMMATIONS. 3 



these red globules passing into vessels that did not easily carry 

 them; and a number of such vessels exists in every part of the sur- 

 face of the body, where, accordingly, the increase of redness may 

 be ascribed to this, that the number of vessels which receive these 

 red globules is now greater than formerly. But Dr. Haller and 

 some others are extremely averse to admit of this error loci, 

 and maintain that the matter may be explained, by the vessels 

 which carry red globules only receiving them in greater quan- 

 tity, whereby these vessels are distended, occupy a greater part, 

 and present the whole visible surface of a red colour. The ex- 

 planation of this will be rendered more easy, by taking notice 

 that the coats of the vessels are white, and always prevent the 

 red colour appearing so fully as it otherwise would do ; and, 

 on examining with the microscope, we find that those which ap- 

 pear white, always contain some red globules, and differ from 

 the larger vessels only in as far as these contain a greater quan- 

 tity, whereby a redness is produced. It makes little difference 

 which of these accounts we please to adopt ; because the in- 

 creased quantity, as well as the error loci, necessarily implies 

 the increased action in these vessels. 



" We are not much concerned here with a particular theory 

 of the increased heat of the part : whether it be owing to the 

 friction of the red globules of the blood upon the vessels, or on 

 one another, or to the particular oscillation of the blood by the 

 nervous fibres of the system. I am not attached to either of 

 these suppositions ; it is enough for us to know that the in- 

 creased motion of the blood is accompanied with an increase of 

 heat ; although I will not say that it is absolutely so, that there 

 may not occur heat without an increase of motion. But the 

 other happens very universally ; and where it is conjoined with 

 the other circumstances, we have no doubt that the increased 

 heat is an evidence of the increased impetus of the blood in 

 these vessels. 



" The same reasoning will apply to the pain and tension : we 

 can see no other power applied to produce the tension but in- 

 creased impetus. I have not here specified the mode of the 

 pain which occurs ; that, you will find, serves as a distinction 

 for the species of inflammation ; but, in general, pain is more 

 frequently owing to over-distention than to almost any other 



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