CHAPTER XLIII 



TEMPERATURE 



SINCE departures from the normal body-temperature are among 

 the fundamental physical signs of disease, and since observations of 

 the temperature of the patient are only less frequent in medical 

 practice than those of the pulse or of the tongue, it is necessary to 

 have as complete an understanding as possible of the principles that 

 regulate the fluctuations of the clinical thermometer. 

 Animals may be divided into two great classes : 



(1) Warm-blooded or homoiothermal animals, or those which have 

 an almost constant temperature. (Mammals and birds.) 



(2) Cold-blooded or poikilothermal animals, or those whose 

 temperature varies with that of the surrounding medium, being 

 always, however, a degree, or a fraction of a degree, above that of the 

 medium. This class includes reptiles, amphibians, fish, embryonic 

 birds and mammals, and probably all invertebrates. 



The temperature of a man in health varies but slightly, being 

 between 36'5 and 37*5 C. (98 to 99 F.). Most mammals have 

 approximately the same temperature : horse, donkey, ox, 37*5 to 38 ; 

 dog, cat, 38-5 to 39 ; sheep, rabbit, 38 to 39'5 ; mouse, 37'5 ; rat, 

 37'9. Birds have a higher temperature, about 42 C. The tempera- 

 ture varies a little in different parts of the body, that of the interior 

 being greater than that of the surface ; the blood coming from the 

 liver, where chemical changes are very active, is warmer than that of 

 the general circulation ; the blood becomes rather cooler in its passage 

 through the lungs. 



The temperature also shows slight diurnal variations, reaching a 

 maximum about 4 or 5 P.M. (37-5 C.) and a minimum about 3 A.M. 

 (36-8 C.) ; that is, at a time when the functions of the body are least 

 active. If, however, the habits of a man are altered, and he sleeps in 

 the day, working during the night, the times of the maximum and 

 minimum temperatures are also inverted. Inanition causes the 

 temperature^ to fall, and just at the onset of death it may be below 

 30 C. Active muscular exercise raises the temperature temporarily 

 by about 0-5 to 1 C. 



