INFL UENCE OF ACTIVITY ON PROTEID METABOLISM. 913 
must contribute, under the ordinary circumstances of a mixed diet, but 
little to the production of muscular energy. 
Many other experiments have been performed of a like nature, and 
leading practically to the same conclusion. A few, however, have given a 
result which has shown a Bomewhat increased amount of nitrogenous 
excretion, 1 but it will be found on an examination of these that in every 
case there has either been an excessive amount of work done, leading to 
probably an abnormal condition of metabolism, 2 or there has been taken 
in with the food an insufficient amount of non-proteid material to pro- 
vide the necessary oxidation and energy for the work required to be done, 
plus the maintenance of body-temperature. Under such circumstances, 
it is clear that the proteid material of the food must be called upon for 
oxidation and the formation of energy, and we should then naturally 
expect an increased amount of urea in the urine. 
Based upon experiments which come under this heading, Pfiliger 3 
and his pupils have shown a tendency of late years to return to the 
original doctrine of Liebig, and to throw over the view which has been 
accepted almost exclusively since the experiment of Fick and Wislicenus 
above referred to. Thus Argutinsky, 4 working with Pfliiger, found, in 
repeating the experiment of Fick and AVislicenus in a somewhat modified 
form, that there was a marked increase (12 to 25 per cent.) of nitrogen 
excreted, if not so much during the actual performance of the work, at 
any rate during the two days succeeding it, and that from 75 to 100 per 
cent, of the total work done coidd be accounted for by oxidation of 
proteid ; even with 100 grms. of sugar added to the diet, there was still 
an excess of N excreted sufficient to account for 25 per cent, of the 
work done. Similar experiments by Krummacher and others yielded a 
like result. 5 It has, however, been pointed out by I. Munk, 6 that the 
conditions of the experiments of Argutinsky are not the same as those of 
Fick and Wislicenus, in so far as the amount of food which was taken 
by Argutinsky and Krummacher had an insufficient caloric value to 
produce the required amount of energy, that of Argutinsky representing 
only 18 calories per kilo. ; that of Krimimacher only 28 calories per 
kilo., whereas a man at rest requires 32 calories per kilo. : as a natural 
result, a part of the proteids of the body was called upon for the pro- 
duction of the necessary energy. That, given a sufficient amount of 
proteid food, and an insufficient amount of non-proteid food, a large 
amount of muscular energy can be produced by oxidation of the proteid 
is no doubt true. Thus, a dog which was kept by Pfiuger for some 
months upon lean meat, containing a very small amount of non-proteid 
1 Cf., for example, Austin Flint, Journ. Anal, and Physiol., London, vol. xi. p. 109, 
and vol. xii. p. 91 ; Pavy, Lancet, London, 1876, vol. ii. Xos. 22-26 ; 1877, vol. i. Xo. 2 ; 
W. Xorth, Proc. Hoy. Soc. London, 188-3, vol. xxxvi. p. 11. 
2 That such nitrogen increase is associated with abnormal conditions, appears from the 
experiments of Oppenheimer {Arch. f. d. ges. Physiol., Bonn, 1S80, Bd. xxii. S. 40 and 
Bd. xxiii. S. 446), of Zuntz and Schermberg (Arch. f. Physiol., Leipzig, 1895, S. 378), and of 
Oddi and Tarulli (Bull. d. r. Accad. med. di Roma, tome xix. pp. 2 and 57). 
3 "Die Quelle der Muskelkraft," Arch. f. d. ges. Physiol., Bonn, 1891, Bd. 1. S. 98. 
4 Arch./, d. ges. Physiol., Bonn, 1889, Bd. xlvi. S. 552. 
5 Ibid., 1S90, Bd. xlvii. S. 454; see also Pfiuger and Bohlaud, ibid., 1885, Bd. xxxvi. 
S. 165 ; Bleibtreu and Bohland, ibid., 1886, Bd. xxxviii. S. 1. 
6 Arch. f. Physiol., Leipzig, 1890, S. 557 (Verhandl. d. physiol. Gesellsch. zu Berlin, 
1S89-90, No. 12). Cf. also Hirschfeld, Firchoic's Archiv, 1890, Bd. cxxi. S. 501, who 
obtained a marked increase of X in the excreta when working on insufficient diet, but not 
when the diet, whether proteid or non-proteid, was sufficient. Further, Sonden and 
Tigerstedt, Skandin. Arch. f. Physiol., Leipzig, 1895, Bd. vi. S. 181. 
VOL. I. — z8 
