604 METABOLISM, NUTRITION AND DIETETICS 



and man. In this way the daily excretion of nitrogen in a man has 

 been reduced to 4 grammes. It is a remarkable fact that while a 

 mixture of carbo-hydrate and fat will act just as well as carbo- 

 hydrate alone in bringing about this reduction in the nitrogen 

 output, fat without carbo-hydrate is much less effective. The 

 hypothesis suggested by Landergren to explain this is alluded to 

 on another page (p. 551). 



The results obtained on fasting men differ in some respects from 

 those obtained on starving animals. In ten days of hunger, Cetti, 

 a professional ' fasting man ' of meagre habit, excreted 112 grammes 

 nitrogen, or an average of n grammes a day. The excretion was 

 least on the eighth, ninth, and tenth days namely, about 9 grammes 

 a day. On the third day it was higher than on the second, and 

 almost as high on 

 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 appar- 



_ fl _ ^al : t v. e Fig. 199. Excretion of Urea in Starvation. A is a curv 



,ntiy 1 nai in me representing the quant ity of urea excreted daily by a 



ordinary tOOd OI fat dog in a starvation period of sixty days. B is the 



man there is a curve of urea excretion in a lean young dog in a 



cn-Aafpr ahiinrlanrp starvation period of twenty-four days. Both are con- 

 structed from Falck's numbers, but in A only every 



Of car DO - hydrates third day j s pu t m> i n order to save space. The num. 



and fats, the pro- bers along the vertical axis represent grammes of urea; 



tein - sparing action those along the a orizontal axis davs flom the beginning 



,5 , ? of starvation, 



of which is most 



pronounced 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 respiratory quotient sank to 

 0-66 to 0-69 even less than the quotient corresponding to oxida- 

 tion of fats alone. The meaning of this, in all probability, is that 

 some of the carbon of the broken-down proteins 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. In another fast 

 of twenty-one days by the same person it was a little less than 

 3 grammes on the last day. The surprisingly small nitrogenous 

 waste in this case is perhaps to be accounted for by the protein- 

 sparing action of the abundant body-fat. The nitrogenous metabo- 



