HISTORICAL AND COMPARATIVE. 457 



e.g., salts, which cause dilatation of the cutaneous vessels, facilitates the excretion 

 of heat ; even salt-water conducts heat better. If alcohol be given internally at 

 the same time, it lowers the temperature. 



(b) Cold may be applied locally by means of ice in a bag, which causes contrac- 

 tion of the cutaneous vessels and contraction of the tissues (as in inflammation), 

 while at the same time heat is abstracted locally. 



(c) Heat may be abstracted locally by the rapid evaporation of volatile sub- 

 stances (ether, carbon disulphide), which causes numbness of the sensory nerves. 

 The introduction of media of low temperature into the body, respiring cool air, 

 taking cold drinks, or the injection of cold fluids into the intestine acts locally, 

 and also produces a more general action. In applying cold it is important to 

 notice that the initial contraction of the vessels and the contraction of the tissues 

 are followed by a stronger dilatation and turgescence. 



227. Heat of Inflamed Parts, 



" Calor " or heat is reckoned one of the fundamental phenomena of inflamma- 

 tion, in addition to rubor (redness), tumor (swelling), and dolor (pain). But the 

 apparent increase in the heat of the inflamed parts is not above the temperature 

 of the blood. Simon, in I860, asserted that the arterial blood flowing to an 

 inflamed part was cooler than the part itself; but v. Blirensprung denies this, as 

 J. Hunter did, and so does Jacobson, Bernhardt, and Laudien. The outer parts 

 of the skin in an inflamed part are warmer than usual, owing to the dilatation of 

 the vessels (rubor) and the consequent acceleration of the blood-stream in the 

 inflamed part, and owing to the swelling (tumor) from the presence of good heat- 

 conducting fluids ; but the heat is not greater than the heat of the blood. It is 

 not proved that an increased amount of heat is produced, owiug to increased 

 molecular decompositions within an inflamed part. 



228. Historical and Comparative. 



According to Aristotle, the heart prepares the heat within itself, and sends it 

 along with the blood to all parts of the body. This doctrine prevailed in the 

 time of Hippocrates and Galen, and occurs even in Cartesius and Bartholinus 

 (1667, " flamula cordis "). The iatro-mechanical school (Boerhave, van Swieten) 

 ascribed the heat to the friction of the blood on the walls of the vessels. The 

 iatro-chemical school, on the other hand, sought the source of heat in the fermenta- 

 tions that arose from the passage of the absorbed substances into the blood (van 

 Helmont, Sylvius, Ettmuller). Lavoisier (1777) was the first to ascribe the heat 

 to the combustion of carbon in the lungs. 



After the construction of the thermometer by Galileo, Sanctorius (1626) made 

 the first thermometric observations on sick persons, while the first calorimetric 

 observations were made by Lavoisier and Laplace. 



Comparative observations are given at 207, ami also under I [ybernation 

 (p. 456). 



