IvATABOLISM OF GLYCOGEN. 465 



average for 14 experiments there were 110 grams of glycogen katabolized on 

 the first day. The quantities per kilogram of body-weight on the first day 

 show marked differences since the variations in body-weight of the different 

 subjects were by no means as great as the fluctuations in the actual amount of 

 glycogen katabolized. On the second day of fasting, which, as has been seen 

 in the previous discussion, appears to represent more nearly than the first 

 day, the true fasting metabolism, the quantity of glycogen is considerably 

 less, ranging from 14.9 to 91.6 grams. It is to be noted that in one of these 

 experiments, No. 81, the records indicate a gain of glycogen amounting to 

 25.7 grams. Similarly a gain is recorded on the fifth day of experiment 

 No. 73. Deferring for the moment the discussion of these gains of glycogen, 

 it is seen that the amount of glycogen katabolized in the average of 13 experi- 

 ments on the second day was 40.3 grams. On the basis of per kilogram of 

 body-weight 0.62 gram was katabolized. The large amounts on the first day of 

 fasting are thus very materially reduced on the second day. Unfortunately, 

 but few experiments continued after the second day, the average amount of 

 glycogen for the third day of 6 experiments being 21.8 grams. Wide fluctu- 

 tions appear, however, even on this day, ranging from 4.2 to 58.9 grams. On 

 the fourth day the glycogen katabolized was nearly constant in the 5 experi- 

 ments, averaging 23.3 grams. The quantities katabolized on the fifth, sixth, 

 and seventh days are somewhat lower, the amounts showing a general tendency 

 to decrease as the fast progresses. The lowest result is noted on the third day 

 of the longest experiment, while on the fourth, sixth, and seventh days, the 

 total amounts katabolized are nearly equal to those of the second. 



Marked irregularities are to be noted in the katabolism as the fast progresses 

 in practically all the experiments. 



Storage of glycogen. On 2 of the 43 fasting days here reported, the figures 

 indicate a storage of glycogen. It was hoped that the data would perhaps 

 indicate the exact source of the stored glycogen, but, unfortunately, the 

 instances of such storage are too few and the quantities stored too small to 

 justify definite conclusions from the results as recorded, and, accordingly, these 

 experiments fail to throw important light on the much discussed question 

 regarding the source of glycogen. 



It may be questioned whether the analytical methods and the computations 

 used in these experiments are sufficiently accurate to warrant the belief that 

 there is an actual storage of glycogen in these two instances. But a close 

 examination of the figures will show that the oxygen consumption and carbon 

 dioxide output may well include a cleavage of protein or oxidation of fat to 

 form glycogen. 153 It is much to be regretted that definite experiments to study 

 this problem with this apparatus have not as yet been reported, although at the 



153 See discussion of probable error in oxygen determination on one of these days, 

 p. 514. 



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