82 HUMAN PHYSIOLOGY. 



COMPARISON OF THE INGESTA AND EGESTA. 



Ingesta. Egesta. 



Protein 120 grams. Urea 40 grams. 



Fat 90 grams. Inorganic salts 32 grams. 



Starch 330 grams. Feces 104 grams. 



Inorganic salts 32 grams. Carbon dioxid 800 grams. 



Water 2,800 grams. Water 3,096 grams. 



Oxygen 700 grams. 



Total 4,072 grams. 



Total 4,072 grams. 



Other estimates as to the amount of the organic substances required daily 

 are as follows: 



Ranke. Voit. Atwater. Moleschott. 



Protein 100 118 125 130 grams. 



Fat 100 50 125 84 grams. 



Starch 240 500 400 404 grams. 



The Energy of the Animal Body. The food consumed daily not only 

 repairs the loss of material from the body, but also furnishes the energy to re- 

 place that which is expended daily in the shape of heat and motion. All the 

 energy of the body can be traced to the chemic changes going on in the tissues, 

 and more particularly to those changes involved in the oxidation of the foods. 



The amount of heat yielded by any given food principle can be determined 

 by burning it to carbon dioxid and water, and ascertaining the extent to 

 which it will, when so liberated, raise the temperature of a given volume of 

 water. This amount of heat may be expressed in calories. A calorie is the 

 amount of heat required to raise the temperature of one kilogram of water one 

 degree Centigrade. 



The following estimates give, approximately, the number of calories pro- 

 duced when the food is reduced within the body to urea, carbon dioxid, and 

 water: 



i gram of protein yields 4,124 kilogram calories, 

 i gram of fat yields 9,353 kilogram calories, 

 i gram of starch yields 4,116 kilogram calories. 



The total number of kilogram calories yielded by any given diet scale can 

 be readily determined by multiplying the preceding factors by the quantities 



