I9I2] Lafayette B. Mendel 135 



Both of these pieces of evidence, therefore, can be taken as 

 strongly contrary to the work of digestion as an explanation of any 

 considerable proportion of the increased metabolism generally noted 

 after the ingestion of food. 



Experiments both on dogs and on men show that foUowing the 

 ingestion of food there is an increased muscle tonus as indicated by 

 the pulse rate, and frequently by the respiration rate, showing that 

 the animal is living on a higher metaboHc plane than formerly. 

 The increased heat is thus a product of cell action, and the question 

 as to its economic value acquires a new significance. A man asleep, 

 with lowest heat production, is of little value to the world ; awake, 

 with no external muscular activity, he has increased internal activity 

 and is capable of intellectnal life. 



The ingestion of protein alone stimulates metabolism with the 

 possibility of some differences in the kinds of protein. Carbohy- 

 drates show rapid effects, not so great as protein, and different car- 

 bohydrates give different results. The metabolism 12 hours after 

 the last meal of a carbohydrate-free, fat-rich diet, with moderate 

 amounts of protein, is much greater than the metabolism under sim- 

 ilar time-conditions after a mixed diet with the same amount of 

 protein. Diabetics with varying degrees of intensity of the disease 

 show marked differences in the total metabolism 12 hours after the 

 last meal. A high acidosis is coincident with a high metabolism. 



A carbohydrate-free, fat-rich diet, eaten by a normal individual, 

 is accompanied by the presence of an acidosis and an increased 

 metabolism. The evidence suggests that coincidental with what 

 is commonly termed a " State of acidosis " there is present in the 

 blood a substance or substances, probably of an acid nature, that 

 stimulate the cells to a greater metabolism. 



ö' 



The influenae of foodstuffs and their cleavage products upon 



heat production 



GRAHAM LUSK 



If meat in large quantity be given to a dog, the heat production 

 rises in the second hour almost to its maximum, reaches its maxi- 

 mum in the third hour and continues at this level through the tenth 



