AND PHYSIOLOGY. 



257 



change (oxydization) dependent upon vital energy, being 

 nearly analogous to the burning of a candle or the combus- 

 tion of wood and coal in the stove. 



456. Process of Producing Animal Heat —As the oxy- 

 gen in the inspired air enters the lungs and is brought into 

 contact with the blood through the wall of the air-cells, the 

 carbon of the venous blood unites with it, forming carbonic 

 acid, and heat is generated. This is precisely the same thing 

 that takes place in the furnace, where the air enters through 

 the draft supplying the oxygen, and the coal furnishes the 

 carbon, the result of the union being heat. But it is not in 

 the lungs alone that this heat is generated : for we have al- 

 ready seen that the blood is highly charged with oxygen as it 

 passes through the arteries to the various organs of the body. 

 And as it passes through the capillaries in every part of the 

 system, it there receives an equivalent of carbon, the w^aste 

 of the system producing carbonic acid, in which operation 

 heat is given off. Hence we see that heat is generated not 

 only in the lungs but in every part of the body, and that it 

 is incessantly being produced, which is a reason why the ex- 

 tremities of the body are constantly kept at their proper tem- 

 perature ; for if all the heat were to be generated in the lungs, 

 very frequently the blood would become chilled in its passage 

 to the extreme capillaries. We also see that forced respira- 

 tion has the same effect as increasing the draft of air into 

 the furnace, and that the fuel of the human system is sup- 

 plied by means of the food placed in the stomach. 



457. Temperature of Human Body. — The temperature of 

 the human system is 98° F., and this it is invariably found to 

 be in all climates and seasons when the individual is in pos- 

 session of perfect health. So that in most climates the tem- 

 perature of the body is above that of the surrounding atmos- 



456. Describe the process. Is all the heat of the body generated in the lungs ? Where 

 in the body is it not generated ? What is the fuel of the body? Where is the draft? 

 451. What is the temperature of the human body ? How is the heat of the body com- 

 pared with that of nearly all climates? 



