606 



JOHN R. MURLIN 



Following Rubner's fundamental observation on the influence of car- 

 bohydrate on the respiratory metabolism of a fasting dog, Magnus-Levy, 

 Johansson, Durig, and DuBois, made confirmatory observations on the hu- 

 man subject (Lusk (h} ). One hundred grams of glucose causes an average 

 increase of nine per cent in the heat production of a man of 75 kilos ; and 

 200 grams one of 12.5 per cent during 3 to 6 hours after the ingestion. The 

 same dose with a smaller man produces a proportionally greater accelera- 

 tion of the metabolism. Lusk and his pupils have found that the period of 

 highest metabolism after heavy sugar feeding to dogs coincides with an 



Fig. 34. After Williams, Riche and Lusk, showing the R.Q., the total metabolism 

 determined by indirect (heavy black line) and direct (broken line) calorimetry as 

 well as the nitrogen elimination (dotted line) during hourly periods after the inges- 

 tion of 1200 grams of meat, by a dog. 



osmotic dilution of the blood caused by the rapid absorption of the sugar, 

 and a sudden fall in the metabolism coincides with a removal of sugar from 

 the circulation by the liver and a rapid elimination of water through the 

 kidney. Lusk believes, therefore, that the heightened metabolism follow- 

 ing rapid absorption of fat or carbohydrate may be called a ''metabolism of 

 plethora/' or, in words of one syllable, oil on the fire. Since a summation 

 effect is produced when carbohydrate and an amino-acid or both are added 

 at a time when fat is producing a maximal effect and from other considera- 

 tions which need not be entered into here, Lusk infers that separate mechan- 

 isms for oxidation of several foodstuffs exist within the body 

 cells. 



