GENERAL METABOLISM. 631 



edge, still, on the other hand, the importance of cell-life, of the metabolism 

 of the cells and their functions, must not be overlooked in considering 

 the metabolism of the body as a whole. 



Interesting glimpses into the course of general metabolism have been 

 obtained by studying the results under definite conditions. The metabo- 

 lism taking place after the complete withdrawal of the food has been 

 studied especially. Under this condition the animal lives at first upon 

 its own stored-up material, and finally attacks its own tissues. The 

 duration and the whole course of the metabolism during starvation depends 

 largely upon the condition of the body at the beginning of the experiment. 

 As soon as a certain definite fraction of the body-substance has been used 

 up, death takes place. Naturally the activity of the metabolism also 

 affects the duration of starvation period. According to the principles 

 enunciated above, therefore, we should expect, a priori, that young in- 

 dividuals would suffer from the withdrawal of nourishment much more 

 quickly than adults. Similarly in the case of animals which in general 

 have a lower metabolism, as with cold-blooded animals, they will sur- 

 vive starvation longer than will the warm-blooded animals. Dogs can 

 live without food for six weeks. Birds live on an average from 5 to 

 20 days, while fish and reptiles may survive for from 6 months to a year. 

 Even in the case of human beings, long periods of fasting have been 

 observed. 1 



The first marked change that results from the withdrawal of all nour- 

 ishment is the loss in weight of the body, which within a relatively short 

 time is followed by a loss in muscular power. The subject sleeps much, 

 and towards the end of the period of starvation is in a somnolent con- 

 dition. The whole metabolism of the animal diminishes simultaneously 

 with the loss in weight. If, however, the amount of material transformed 

 is compared to a kilogram of body- weight, it will be found that the metabo- 

 lism is only slightly changed from that of a well-nourished animal. In 

 a short time the fasting animal adjusts itself to a minimum metabolism, 

 which remains constant for quite a while. First of all the animal makes 

 use of its stores of carbohydrates and fat. The former are soon exhausted. 

 From the beginning of the starvation period, albumin is continuously being 

 decomposed. The amount of albumin which the fasting organism must 

 decompose in order to accomplish the necessary metabolism, depends 

 chiefly upon the amount of nitrogen-free substances which are present. 

 If the animal is able to consume a considerable amount of the latter, then 



1 L. Luciani: Das Hungern, Hamburg-Leipzig, 1890. J. E. Johannson, E. Lundgren, 

 Klas Sonden, and Robert Tigerstedt: Skand. Arch. Physiol. 7, 29 (1896). C. Lehman, 

 F. Miiller, I. Munk, H. Senator, and N. Zuntz: Virchow's Arch. 131, Suppl. 1 (1893). 

 R. Tigerstedt: Nordisk, Medic. Arch. No. 37 (1897). C. Voit: Z. Biol. 41, 113 (1901). 

 Siegfried Weber: Ergeb. Physiol. (Asher and Spiro) Jg. 1, Abt. 1, p. 702 (1902). 



