Katabolism of Protein. 457 



76.6 grams, a material increase over the average for the first day, thus sub- 

 stantiating the contention made by Prausnitz "* that the protein katabolism on 

 the first day of fasting is regulated in large measure by the amount of glycogen 

 in the body. Furthermore, reference to the quantities of glycogen katabolized 

 (see table 228) on the second days of these experiments shows that the amounts 

 of katabolized glycogen in all but one instance were greatest on the first day. 



Computed on the basis of per kilogram of body-weight, the protein kata- 

 bolism on the second day of fasting is reasonably constant, experiments Nos. 

 79 and 80 being the marked exceptions. Omitting these experiments, the 

 widest variation from the average (1.21 grams) is 0.28 gram. 



The uniformity of the protein katabolism is still further supported by the 

 results on the third day of fasting, the maximum amount being 90.2 grams, 

 the minimum 65.9 grams, and the average 78.5 grams, somewhat more than 

 the average for the second day. The average per kilogram of body-weight is 

 1.28 grams, and the fluctuations from this average in the different experiments 

 are very small. 



Similarly, constancy in the results from day to day is observed on the fourth 

 day of fasting, the amounts on the basis of per kilogram of body-weight being 

 practically uniform after the third day. 



In comparing the results of protein katabolism as indicated in this table, 

 it is important to bear in mind that the factor for the computation of protein 

 here employed is 6.0, while the factors 6.3 and 6.25 are commonly used to 

 express the ratio between nitrogen and protein. Obviously, the use of either 

 of these latter figures, would indicate a somewhat greater protein katabolism 

 than is recorded in the table. 



The results show that on the first day of fasting the amounts are extremely 

 irregular and that the fasting protein katabolism can not be said to be estab- 

 lished before the second day. 



The bearing of the protein katabolism on the protein requirement, the 

 influence of the previous store of glycogen, 144 fat and protein, and the relation 

 of the protein katabolism to the total active mass of protoplasmic tissue are 

 problems all closely related, but discussion of them in this place would be 

 beyond the confines of this report. With the publication of experiments made 

 subsequent to these here reported, it is hoped that these problems may be more 

 fully dealt with. 



Certain of the data accumulated in this series of experiments, while admit- 

 tedly too meager to serve as the basis for the enunciation of a theory of the 

 effect of inanition upon protein katabolism, are sufficiently suggestive to 

 warrant more complete examination. 



143 Zeit. f. Biologie (1892), 29, p. 151. 



144 The interesting discussion of the relation between the store of glycogen in the 

 body and the proteid katabolism by Landergren (Skan. Archiv f. Physiol. (1903), 

 14, p. 169), is supplemented by the observations on the actual glycogen katabolism 

 observed in these experiments. 



