CHEMICAL REGULATION OF METABOLISM 389 



The subcutaneous or intravenous injection of Guanidine or Methyl- 

 guanidine was found by Paton to lead to marked symptoms of tetany. 

 Previous observers had established the fact that guanidine causes 

 fibrillary twitchings of muscular tissue through stimulation, followed 

 by paralysis of the myoneural junctions, and Fuhner, in 1906, demon- 

 strated that this action is antagonized by calcium salts. The origin 

 of parathyroid tetany would therefore appear to reside in a disturbance 

 of nitrogenous metabolism, and especially in the metabolism of the 

 guanidine derivatives. The aggravation of symptoms which accom- 

 panies the administration of a high meat-diet is thus accounted for. 

 Whether the parathyroids control the metabolism of other nitrogenous 

 constituents of the diet besides those which contain a guanidine nucleus, 

 is unknown, but the alkalosis which accompanies parathyroidectomy 

 suggests that the products of metabolism which the parathyroids 

 remove or elaborate are strongly basic substances such as might be 

 derivable from the decomposition of Diamino Acids, of which, of course, 

 arginine is an example. 



It has recently been shown by Uhlenhuth that tetany may be induced 

 in amphibian larvae which do not possess parathyroids (Amblystoma) ; 

 by the administration of thymus tissue, and he suggests that the func- 

 tion of the parathyroids is to remove or render non-toxic substances 

 produced by the Thymus. This would also explain the prevalence of 

 tetany in children, since the thymus degenerates as maturity is attained. 

 While this is very possible, it must also be remembered that the thymus 

 is unusually rich, among animal tissues, in Thymus Nucleic Acid, which 

 yields Guanine among its decomposition-products. Now guanine, 

 when oxidized, yields, among other products, guanidine, so that the 

 tetany observed by Uhlenhuth may have had a dietary rather than a 

 specific glandular origin. 



REFERENCES. 



GENERAL: 



Biedl: The Internal Secretory Organs, their Physiology and Pathology, trans., 

 Forster, London, 1913. 



Swale, Vincent: Internal Section and Ductless Glands, London, 1912. 



Schajer: The Endocrine Organs, London, 1916. 



Paton: The Nervous and Chemical Regulators of Metabolism, London, 1913. 



Starling: The Principles of Human Physiology, Philadelphia, 1915. 

 RESPIRATION: 



Pembrey: Respiratory Exchange, Recent Advances in Physiology and Biochem- 

 istry, by Leonard Hill, London, 1906. 



Robertson: Biochem. Zeit. Festband fur H. J. Hamburger, 1908, p. 287. Arch. 

 Int. de Physiol., 1908, 6, p. 388. Pfliiger's Arch., 1912, 145, p. 329. 



Winterstein: Pfliiger's Arch.,- 1911, 138, pp. 159 and 167. 



Laqueur and Verzar: Ibid., 1912, 143, p. 395. 



Douglas, Haldane, Henderson and Schneider: Phil. Trans. Roy. Soc., 1913, 203B, 

 p. 185. 



Douglas: Ergeb. d Physio!., 1914, 14, p. 338. 



Scott: Am. Jour. Physiol., 1917, 44, p. 196. 

 CIRCULATION: 



Stewart; Jour. Exp Med , 1912, 15, p. 547. 



MacLeod and Pearce: Am. Jour. Physiol., 1911-12, 29, p. 419. 



