122 THE AMINO ACIDS 



sugar. To test the Zuntz hypothesis Benedict has 

 attempted to produce the effects of food ingestion 

 such as augmented mechanical work through increased 

 peristalsis produced by large doses of purgatives, as 

 sodium sulphate. In spite of greatly increased peris- 

 talsis the administration of sodium sulphate failed to 

 show any measurable increase in metabolism. "In the 

 belief that when the intestine is full of partly digested 

 food products and epithelial debris, the amount of 

 mechanical work thereby incurred might be greater 

 than that involved in several powerful peristaltic 

 waves, experiments were made in which relatively 

 large amounts of agar-agar were ingested, thus pro- 

 ducing a bulky, voluminous stool. The agar-agar 

 being practically non-oxidizable, there was no great 

 complication due to the combustion of carbohydrate 

 from the agar-agar. With the agar-agar it is reason- 

 able to assume that there must have been an extensive 

 segmentation process as well as peristaltic waves. 

 But even under these conditions on the ideally con- 

 trolled experiments there was absolutely no increase 

 in metabolism. In so far, then, as the experiments on 

 men show with controlled conditions, the work of 

 peristalsis and probably of segmentation is not suffi- 

 cient to be measured in the great daily energy trans- 

 formation of the body. It is impossible to think of 

 muscular activity of any kind taking place without 

 some slight increased metabolism, but the amount 

 involved in intestinal activity must be so small as to 



