180 Life and Health 



The normal temperature is maintained with slight varia- 

 tions throughout life. Indeed, a change of more than a 

 degree above or below the average indicates some disease 

 in the organism or some unusual influence. It is evident, 

 then, that the mechanisms which regulate the temperature 

 of the body must be exceedingly sensitive. 



The two chief means of regulating the temperature of 

 the body are the lungs and the skin. 



Experiment 81. To show the natural temperature of the body. 

 Borrow a physician's clinical thermometer, and take your own tem- 

 perature, and that of several friends, by placing the instrument under 

 the tongue, closing the mouth, and holding it there for five minutes. 

 Read it while in position, or the instant the. instrument is removed. 

 The natural temperature is about 98^ Fahr. The thermometer 

 should be thoroughly cleansed after each use. 



If a doctor's thermometer is not to be obtained, unfasten and use 

 one of the little thermometers often found on calendars and adver- 

 tising circulars. The bodily temperature will not be indicated accu- 

 rately in this crude way. 



NOTE. A substitute for a clinical thermometer may be readily 

 contrived by taking an ordinary house thermometer from its tin case 

 and cutting off the lower part of the scale so that the bulb may pro- 

 ject freely. With this instrument the pupils may take their own and 

 each other's temperatures, and it will be found that, whatever the 

 season of the year or the temperature of the room, the thermometer 

 in the mouth will record about 99 Fahr. Care must, of course, be 

 taken to keep the thermometer in the mouth till it ceases to rise, and 

 to read while it is still in position. PROFESSOR H. P. KOWDITCH. 



271. The Skin as a Heat Regulator. The great regulator 

 of the bodily temperature is the skin. 



First, the skin regulates the loss of heat by means of 

 the vaso-motor mechanism. The greater the quantity of 

 blood which passes through the skin, the greater will be 

 the loss of heat by conduction, radiation, and evaporation. 



