INFLUENCE 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 somewhat 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, Pniiger 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 Tick and Wislicenus 

 above referred to. Thus Argutinsky, 4 working with Pfliiger, found, in 

 repeating the experiment of Tick and Wislicenus 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 could be accounted for by oxidation of 

 proteid ; even with 100 grins, 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 

 Tick 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 Krummacher 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 Pfliiger for some 

 months upon lean meat, containing a very small amount of non-proteid 



1 Cf., for example, Austin Flint, Journ. Anat. and PhysioL, London, vol. xi. p. 109, 

 and vol. xii. p. 91 ; Pavy, Lancet, London, 1876, vol. ii. Nos. 22-26 ; 1877, vol. i. No. 2 ; 

 W. North, Proc. Hoy. Soc. London, 1883, 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, 1880, Bd. xxii. S. 40 and 

 Bd. xxiii. S. 446), of Zuntz and Scherniberg (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.f. d. ges. PhysioL, Bonn, 1889, Bd. xlvi. S. 552. 



5 Ibid., 1890, Bd. xlvii. S. 454; see also Pfliiger 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, 

 1889-90, No. 12). Cf. also Hirschfeld, Firdww's Archiv, 1890, Bd. cxxi. S. 501, who 

 obtained a marked increase of N in the excreta when working on insufficient diet, but not 

 when the diet, whether proteid or non-proteid, was sufficient. Further, Sonde'n and 

 Tigerstedt, Skandin. Arch.f. PhysioL, Leipzig, 1895, Bd. vi. S. 181. 



VOL. I. 58 



