44 



although oxidation at any point raises the heat of the 

 blood at the point, this heat is carried by the blood to 

 other parts, to which the surplus is given up, while blood 

 cooled in the skin goes to the hotter inward parts to cool 

 them and be warmed itself. In fact, heat is expended by 

 conduction and radiation, through respiration, perspira- 

 tion, and heat given to the urine and faeces. It is, 

 therefore, largely, 75 to 80 per cent., carried off through 

 the skin and the lungs; 60 to 70 per cent, is lost by 

 radiation to the air and other bodies with which the body 

 comes in contact; 20 to 30 per cent, is lost by the evap- 

 oration of sweat, 4 to 8 per cent, by the warming of ex- 

 pired air, urine and feces, and 1 to 2 per cent, by cold 

 food that is taken in. Radiation acts more favorably 

 where the surroundings are cool and the air in motion, 

 as on a breezy day. Conduction is carried on best where 

 the surrounding air is cool, especially if it is moist, for 

 moist air is a better conductor of heat than dry air. 

 Evaporation is very important in hot weather or where 

 men work in hot air. 



Even in health the temperature may range from 98.6 

 to 99.5, and a degree or two below or above is not danger- 

 ous. When a person first gets up in the morning his 

 temperature is apt to be subnormal, but after food and 

 exercise have been taken it becomes normal and stays so 

 till the end of the day, when, if the person is tired, it may 

 go up a little. If a person is tired out, the temperature 

 is apt to be subnormal. There is also in the body what 

 is called the vital tide, which is highest afternoon and 

 evening and lowest in the morning. 



The rate of production of heat varies greatly in differ- 

 ent people. One person uses a certain amount of tissue 

 more quickly than another, that is, he lives faster. More- 

 over, size makes a difference in that a small body has 

 more surface to its weight than a large one and so has 

 to produce the same amount of heat at a faster rate in 

 order to maintain the right temperature. Taking food 

 increases heat, probably because of the muscular effort 



