EMPLOYMENT OF HEAT. 337 



20 min.) very rapidly, and with the same phenomena, while the bodily temperature 

 rises 4 to 5 C. In rabbits the body-weight diminishes 1 grm. per min. Birds 

 bear a high temperature somewhat longer ; they die when their blood reaches 48 

 to 50 C. 



Even man may remain for some time in air at 100-110-132 C, but in ten to 

 fifteen minutes there is danger to life. The skin is burning to the touch, and red ; 

 a copious secretion of sweat bursts forth, and the cutaneous veins are fuller and 

 redder. The pulse and respirations are greatly accelerated. Violent headache, ver- 

 tigo, feebleness, and stupefaction, indicate great danger to life. The rectal tempera- 

 ture is only 1 to 2 C. higher. The high temperature of fever may even be 

 dangerous to human life. If the temperature remains for any length of time at 

 42*5 C, death is almost certain to occur. Coagulation of the blood in the arteries 

 is said to occur at 42*6 C. If the artificial heating does not jyroduce death, fatty 

 infiltration and degeneration of the liver, heart, kidneys, and muscles begin after 

 thirty-six to forty-eight hours. 



Cold-blooded animals, if placed in hot air or warm water, soon have their temperature raised 

 6 to 10 C. The highest temperature compatible with life in a frog must be below 40 C, as the 

 frog's heart and muscles begin to coagulate at this temperature. Death is preceded by a stage 

 resembling death, during which life may be saved. 



Most of the juicy plants die in half an hour in air at 52 C, or in water at 46 C. (Sachs). 

 Dried seeds of corn may still germinate after long exposure to air at 120 C. Lowly organised 

 plants, such as algae, may live in water at 60 C. (Hoppe-Seyler). Several bacteria withstand 

 a boiling temperature ( Tyndall). 



222. EMPLOYMENT OF HEAT. Action of Heat. The short, but not intense, action of 

 heat on the surface causes, in the first place, a transient slight decrease of the bodily tempera- 

 ture, partly because it retards reflexly the production of heat, and partly because, owing to the 

 dilatation of the cutaneous vessels and the stretching of the skin, more heat is given off. A 

 warm bath above the temperature of the blood at once increases the bodily temperature. 



Therapeutic Uses. The application of heat to the entire body is used where the bodily 

 temperature has fallen, or is likely to fall, very low, as in the algid stage of cholera, and in 

 infants born prematurely. The general application of heat is obtained by use of warm baths, 

 packing, vapour baths, and the copious use of hot drinks. The local application of heat is 

 obtained by the use of warm wrappings, partial baths, plunging the parts in Avarm earth or 

 sand, or placing wounded parts in chambers filled with heated air. After removal of the 

 heating agent, care must be taken to prevent the great escape of heat due to the dilatation of 

 the blood-vessels. 



223. INCREASE OF TEMPERATURE POST-MORTEM. Phenomena. Heidenhain found 

 that in a dead dog, before the body cooled, there was a constant temporary rise of the tempera- 

 ture, which slightly exceeded the normal. The same observation had been occasionally made 

 on human bodies immediately 'after death, especially when death was preceded by muscular 

 spasms [also in yellow fever]. Thus, Wunderlich measured the temperature fifty-seven minutes 

 after death in a case of tetanus, and found it to be 45*375 C. 



Causes. (1) A temporary increased production of heat after death, due chiefly to the change 

 of the semi-solid myosin of the muscles into a solid form (rigor mortis). As the muscle 

 coagulates, heat is produced. All conditions which cause rapid and intense coagulation of the 

 muscles e.g., spasms, favour a. post-mortem rise of temperature (see 295) ; a rapid coagulation 

 of the blood has a similar result ( 28, 5). 



(2) Immediately after death a series of chemical processes occur within the body, whereby heat 

 is produced. Valentin placed a dead rabbit in a chamber, so that no heat could be given oft' 

 from the body, and he found that the internal temperature of the animal's body was increased. 

 The processes which cause a rise of temperature post-mortem are more active during the first 

 than the second hour ; and the higher the temperature at the moment of death, the greater is 

 the amount of heat evolved after death. 



(3) Another cause is the diminished excretion of heat post-mortem. After the circulation is 

 abolished, within a few minutes little heat is given off from the surface of the body, as rapid 

 excretion implies that the cutaneous vessels must be continually filled with warm blood. 



224. ACTION OF COLD ON THE BODY. Phenomena. A short temporary 

 slight cooling of the skin (removing one's clothes in a cool room, a cool bath for a 

 short time, or a cool douche) causes either no change or a slight rise in the bodily 

 temperature. The slight rise, when it occurs, is due to the stimulation of the skin 



T 



