METABOLISM, NUTRITION AND DIETETICS 463 



the fourth as on the third. A similar rise in the nitrogen 

 excretion on the second day has been observed in other 

 fasting men, but is either rare or absent in fasting dogs. 

 The explanation apparently is that in the ordinary food 

 of man there is a greater abundance of carbo-hydrates 

 and fats the proteid-sparing action of which is most pro- 

 nounced at the very beginning of the starvation period. 

 The quantity of chlorine and alkalies in the urine was also 

 diminished, while the phenol was increased. The respi- 

 ratory quotient sank to o'66 to 0*69 even less than the 

 quotient corresponding to oxidation of fats alone. The 

 meaning of this, in all probability, is that some of the 

 carbon of the broken-down proteids was laid up in the 

 body as glycogen (Zuntz). In another professional fasting 

 man (Succi) with a considerable amount of body-fat, the 

 excretion of nitrogen was found to diminish continuously 

 during a fast of thirty days, being less than 7 grammes on 

 the tenth day, and, what seems almost incredible, not much 

 over 3 grammes on the last day. The surprisingly small 

 nitrogenous waste in this case is perhaps to be accounted 

 for by the proteid-sparing action of the abundant body-fat. 

 The nitrogenous metabolism has also been investigated 

 during long-continued hypnotic sleep (Hoover and Sollmann). 

 The results were very much the same as in an ordinary 

 starvation experiment. 



It might be supposed that if an animal was given as much 

 nitrogen in the food in the form of proteids as corresponded 

 to its daily loss of nitrogen during starvation, this loss would 

 be entirely prevented and nitrogenous equilibrium restored. 

 The supposition would be very far from the reality. If a 

 dog of 30 kilos weight, which on the tenth day of starva- 

 tion excreted 11*4 grammes urea, had then received a daily 

 quantity of proteid equivalent to this amount that is to 

 say, about 34 grammes of dry proteid, or 175 grammes of 

 lean meat the excretion of nitrogen would at once have 

 leaped up to nearly double its starvation value. If the 

 quantity of proteid in the diet was progressively increased, 

 the output of urea would increase along with it, but at an 

 ever-slackening rate ; and at length a condition would be 

 reached in which the income of nitrogen exactly balanced the 



