1913.] Metabolism in its Relation to the Thyroid Gland. 553 



tolerance for carbohydrates makes it difficult to give a correct interpretation 

 to his observations on the effects of thyroidectomy. 



Eppinger, Falta, and Eiidinger* further supported their arguments by 

 observations on the behaviour of thyroidectomised animals to injections of 

 adrenin. They stated that the glycosuria which takes place in normal 

 animals after the injection of adrenin does not occur in thyroidectomised 

 animals. But a repetition of these experiments by Underhill and his 

 collaborators^ failed to confirm these results. Underhill showed that one and 

 the same normal animal under similar conditions differs considerably in its 

 readiness to respond to the injection of adrenin by the excretion of sugar in 

 the urine and that thyroidectomised animals respond to adrenin as readily as 

 normal animals. 



Whether excessive secretion of the thyroid hormone, produced by thyroid 

 feeding, affects the carbohydrate metabolism of the normal organism has not 

 been studied experimentally. Clinically it has been observed that thyroid 

 administration sometimes produces a tendency to alimentary glycosuria. 



From this brief review of the literature it will be evident that the relation 

 of the thyroid gland to metabolism is not yet clearly understood. The effect 

 of the thyroid hormone on the metabolism of the normal organism is uncertain 

 and variable, so that a secure experimental basis is lacking and that consider- 

 able discrepancies exist between the observations of different authors. Most 

 observers agree, however, in attributing to the thyroid secretion a direct 

 stimulating influence on the nitrogen metabolism and on the total metabolism. 

 To the latter factor they attribute, as a rule, the effect which the administra- 

 tion of thyroid gland has on the fat metabolism. 



The Effect of Thyroid Feeding on the Glycogen-content of the Liver. 



The observations recorded below show clearly that the thyroid hormone has 

 a marked and very peculiar effect on the carbohydrate metabolism. If rats, 

 kept on a carbohydrate rich diet (bread and milk) are fed for from two to eight 

 days with relatively small doses of fresh thyroid gland (sheep's thyroid was 

 used mostly) the glycogen-content of the liver falls so low that the glycogen 

 cannot be estimated gravimetrically in the liver. One must, of course, take 

 into account here, that in a rat only 4-6 grin, of liver tissue are available for 

 analysis, so that a glycogen-content below - l-0'2 per cent, cannot be 

 determined accurately. Such low values, which in a normal rat are found 

 only after 10-15 hours' fasting, are described as a " trace " in the tables 



* Eppinger, Falta, and Eiidinger, loc. cit. 



t Underhill and Hilditch, loc. cit. ; Underhill, ' Anier. Journ. Physiol.,' 1911, vol. 27, 

 p. 311. 



