1913.] Metabolism in its Relation to the Thyroid Gland. 551 



tolerance for carbohydrates — has sometimes been found to occur in 

 myxcedema.* 



It is remarkable, however, that the attempts to verify these conclusions in 

 the normal organism by producing experimentally a condition of excessive 

 secretion of the gland — by means of feeding with thyroid gland, — or a 

 condition of insufficient secretion of the gland — by extirpation of the thyroid 

 gland — have on the whole not been successful. It is as yet not clear how the 

 internal secretion of the thyroid gland produces its action on the metabolism. 

 Nor do we know, at present, how the actions of this hormone on the different 

 aspects of metabolism are related to one another. 



Moreover different observers have obtained very contradictory results. 

 Experimentally produced hypersecretion of the gland, brought about by 

 feeding with thyroid gland, is frequently followed by a marked increase in 

 the total metabolism and in the nitrogen metabolism, but in some experiments 

 such an effect has failed to appear or is much less marked.f The conditions 

 which determine the effect of thyroid administration on nitrogen metabolism 

 are, as yet, not understood. And if the effect on the nitrogen metabolism 

 does occur, the distribution of the urinary nitrogen is, as we pointed out in a 

 previous communication^ the reverse of what one would expect to find on the 

 general assumption that the thyroid secretion acts directly on the endogenous 

 nitrogen metabolism. 



A similar uncertainty exists with regard to the question how the carbo- 

 hydrate metabolism is affected by the thyroid secretion. So far most 

 experimental observations on this point have been made on thyroidectomised 

 dogs, in which, owing to the close anatomical relationship between the 

 thyroid and the parathyroid, the separate effects of thyroidectomy and of 

 parathyroidectomy cannot easily be recognised. This probably accounts 

 for the contradictory results obtained at first by different observers. 



* For a detailed account of the literature on metabolism in Graves' disease and in 

 myxcedema the reader is referred to the articles by Bahel Hirsch and by von Bergmann, 

 in Oppenheimer's 'Handbuch der Biochemie,' 1911, vol. 3 and vol. 4, to the article by 

 Magnus-Levy, in von Noorden's ' Metabolism and Practical Medicine,' vol. 3, 1907, and 

 to the third Lettsomian Lecture, by A. E. Garrod, ' Lancet,' 1912, p. 629. 



t Marked effects were observed, amongst others, by : — In man : Bleibtreu and 

 Wendelstadt ('Deutsche med. Wochenschrift,' 1895, p. 346), Magnus-Levy (' Zeitschr. f. 

 klin. Medizin,' 1897, vol. 33, p. 269), Andersson and Bergman (' Skand. Archiv f. 

 Physiologie,' 1898, vol. 8, p. 326). In dogs : Boos (' Zeitschr. f. phys. Chemie,' 1895, vol. 21, 

 p. 19 ; ibid., 1896, vol. 22, p. 58 ; ibid., vol. 25, p. 12), Voit (' Zeitschr. f. Biologie,' 

 1897, vol. 35, p. 116), Oswald (' Zeitschr. f. phys. Chemie,' 1899, vol. 27, p. 39). No 

 marked effects were observed by : — In man : Magnus-Levy, loc. cit. ; in dogs : Underbill 

 and Saiki ('Journ. Biol. Chem.,' 1908, vol. 5, p. 225), and a number of other workers, 

 whose results are tabulated in the article by Bahel Hirsch quoted above. 



| Krause and Cramer, ' Physiol. Soc. Proc.,' 1912, p. xxiii, ' Journ. Physiol.,' vol. 44. 



