RELATION TO MUSCULAR ACTIVITY 153 



uric acid, especially the formation of allantoin which is so 

 prominent in many animals (vide infra).. 



As far as the endogenous fraction is concerned it is known 

 that the purin bases set free in the disintegration of cellular 

 nuclei in all tissues eventually appear in the form of urinary 

 purins. There is reason for avoiding a restricted concep- 

 tion which would make the leucocytes, the muscles, the 

 digestive glands 10 or the kidneys alone responsible for the 

 endogenous production of uric acid ; it is better to look upon 

 it as the expression of a continuous and general cellular 

 wear. Precisely because this process of wearing out and 

 gradual removal of cells is a very constant and regular one, 

 at least when serious pathological changes are not present, 

 a relative constancy in the endogenous urinary purin frac- 

 tion is to be expected for each individual, as first observed 

 by E. Burian and H. Schur and afterwards confirmed by a 

 number of other writers. 11 Briefly stated, the active metab- 

 olism of the growing body, the experimental exaggeration of 

 glandular activity by pilocarpin, the increase of cell de- 

 struction by use of Rontgen rays, and very many pathologi- 

 cal disturbances like phosphorus poisoning, hepatic atrophic 

 cirrhosis, jaundice, Eck's fistula, fever, leukaemia, etc., are all 

 capable of increasing the endogenous fraction of urinary 

 purins. 12 



Relation of Purin Metabolism to Muscular Activity. 

 There is only one point which requires any further dis- 

 cussion in this connection, namely, that of the relation of the 

 purins to muscular labor, 13 a matter heretofore dealt with in 



10 O. 8iven (Helsingfors), Pfliiger's Arch., 146, 449, 1912. 



11 Cf. E. W. Rockwood, Amer. Jour, of Physiol., 12, 38, 1904; F. Mares, 

 vide infra. 



12 B. Hirschstein (F. Umber's Clinic), Arch. f. exper. Path., 57, 229, 1907; 

 Th. Brugsch and A. Schittenhelm, Zeitschr. f. exper. Path., 4, 761, 1907; 

 O. Sive"n (Helsingfors), Skan. Arch. f. Physiol., 18, 177, 1906; S. Bondi and 

 F. Konig, Wiener med. Wochenschr., 1910, Nos. 44-45 ; F. Mares, F. Smetanka 

 (Physiol. Institut. Czech. Univ., Prague), Pnuger's Arch., 134, 59, 1910; 138, 

 217, 1911. 



18 R. Burian, Med. Klinik, 1905, No. 6, and 1906, Nos. 19-21. 



