24 ANALYSIS OF DISTURBANCES OF METABOLISM 



of digestion, and that with a superabundant nourishment these increases in 

 metabolism can be pushed still further, was for a long time the predominant 

 view (Zuntz and v. Mering). Yet lately authors have come more and more 

 to the conclusion that the increase in the labor of the digestive organs is not 

 sufficient to explain the heat production after intake of nourishment. Inves- 

 tigations on this point have been carried on in patients, and have shown 

 that the increase in metabolism produced by the administration of food 

 is very much greater in some individuals than in others. These results have 

 increased our doubts regarding the correctness of this prevalent opinion (see 

 below) . 



Physiologists have determined the increase of metabolism after physical 

 exertion even more minutely than that following the introduction of food. 



The promptness and delicacy of the changes in the amount of oxidation 

 after muscular labor are almost astonishing. 



Increase in the peristalsis of the smooth musculature of the intestine 

 after the introduction of mineral salts and after the administration of food, 

 changes of the mechanism of respiration, unconscious muscular effort in 

 strained positions of the body or when the temperature of the skin is reduced, 

 all of these factors influence very notably the interchange of gases. Of course 

 a much more striking variation becomes apparent in tests with muscular activ- 

 ity of a type which can be mechanically measured. 



Eegarding the degree to which the process of oxidation may be increased, 

 when the amount of work is increased, Zuntz and Katzenstein have given us 

 exact figures. It is an absolute law that Oj consumption and CO, formation 

 increase with the amount of muscular labor. Accordingly, the interchange 

 of gases is greater when the individual is standing than when he is in the 

 recumbent posture. The increase is slight if the person is standing in a com- 

 fortable position; it amounts to about 20 per cent, of the "rest value" if 

 the person is standing erect as in military drill. 



In walking the consumption of products becomes from 2 to 4 times as 

 great, according to the rapidity of the pace; in rapid hill climbing it is 5 

 times as great as the normal, and even more. 



Proportionally to the interchange of gases the heat production is increased 

 by work (in comparison to rest values), as Atwater and Benedict have deter- 

 mined by direct calorimetry. About two-thirds of the energy set free by 

 increased decomposition is utilized in heat production, and under ordinary 

 circumstances only one-third in mechanical work. (Under the influence of 

 practice the utilization of energy for the performance of labor may increase 

 just as it diminishes under the influence of exhaustion.) 



These are the values which have been estimated in the healthy. As to 

 the way in which labor .increases the total metabolism in disease, and how 

 much useful energy in the shape of chemical activity the diseased body gets 

 from the increased decomposition and from the utilization of its own muscles, 

 only very isolated reports are at hand. 



From the reply to these questions, conclusions in regard to pathologic 

 metabolism will inevitably result. 



