THE PRO! ELYS AND THEIR METABOLISM 



131 



In diagram ITT we have a graphic illustration of one of Lusk's experi- 

 ments on a dog showing the influence of the ingestion of 1200 grams of 

 Iran meat on the metabolism of the dog. During the two hours before 

 iho meat ingestioii, the heat production was 22 to 23 calories per hour. 

 Within two hours after the meat ingcstion the heat production went up to 

 over 35 calories per hour, reached 44 during the third hour and remained 



22 23 I 2 3 4 5 6 7 8 9 10 I) I? 13 14 15 16 17 18 19 20 21 

 HOURS AFTE.R 1200 GRAMS MEAT 



DIAGRAM III. Showing the respiratory quotient, 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 ingestion of 1200 

 of in (fat. 



at that high level for about eight hours, gradually coming down and reach- 

 ing the basal level at the end of twenty-two hours. Ordinarily we notice 

 increased heat production as a result of increased oxidation processes going 

 on in the cells, as during periods of greater- activity. The increase in 

 Lusk's experiments corresponds to an increase in metabolism caused by vio- 

 lent exercise, and yet the animal was lying perfectly quietly and at rest. 



Voit assumed that this marked increase in oxidation and heat forma- 

 tion -was due to the cells being stimulated by the presence of food in the 

 blood brought to them, and that the intensity of metabolism of a cell was 

 a function of the quality and quantity of food material surrounding the 



