METABOLISM. 47 j 



again. By making proper provision to note the increase in weight of 

 the sulphuric acid and soda lime vessels, the quantitative amounts of 

 water vapor and carbon dioxide given off by the subject may be readily 

 determined ; and further, if the loss in weight of the oxygen cylinder 

 is recorded, the amount of oxygen absorbed may be determined. 

 Numerous incidental corrections are necessary for unusual accuracy 

 in these determinations, but the principle is fundamentally that just 

 outlined. 



"For measuring the heat, the apparatus as a calorimeter must next 

 be considered. The inner chamber of copper is surrounded by three 

 walls, one of zinc, and two of wood. With the intervening air spaces 

 between these walls, the construction is not unlike that of a refrig- 

 erator, and hence heat insulation is secured. When a man enters a 

 chamber constructed on this principle, the insulation is so perfect that 

 soon the temperature resulting from the heat production in the body 

 would become unbearable. As houses are heated in winter by passing 

 hot water through pipes, this small house or individual room is cooled 

 by passing cold water through pipes or heat absorbers. Special elec- 

 trical connections prevent any loss of heat from the walls, and by not- 

 ing the quantity of water passing through the heat-absorbing system, 

 and the temperature through which it is warmed, the measurement of 

 heat is readily made." 



Effect of Food on Respiratory Exchange. 



There is an increase of respiratory exchange that is the intake of 

 and outtake of C0 2 in all cases after the taking of food. The 

 gaseous exchange is most markedly elevated in the first two hours, 

 which diminishes four to five hours after breakfast. 



Fat causes a 10-per-cent. increase in the respiratory exchange, 

 proteids a rise of 30 per cent., whilst carbohydrates increase the 

 giving off of C0 2 more than the taking in of oxygen. In rats with 

 a meal rich in carbohydrates, C0 2 rose to 97 per cent., the oxygen to 

 35 per cent, above the values obtained in the fasting condition. 



The Effect of Absolute Rest and Sleep on Metabolism. 



The minimal amount of metabolism as a rule is smaller. During 

 sleep the consumption of oxygen sinks from one to six per cent.; the 

 amount of carbon dioxide during sleep is decreased 6.5 per cent. In 

 absolute rest of the body the intake of oxygen is decreased and the out- 

 take of carbon dioxide diminished. 



