68 Cramer and M'Call 



formed from protein is excreted in the urine as sugar, while in experi- 

 mental hj'perthyroidism it is oxidised. Another point in favour of the 

 interrelationship is the condition of the nitrogen distribution in the urine 

 after thyroid feeding. If the thyroid hormone affected the protein meta- 

 bolism directly, one would expect, as Cra;mer and Krause (7) pointed out, 

 an increased excretion, especially of the end-products of endogenous protein 

 metabolism. But this expectation is not fulfilled : the excretion of these 

 substances remains unchanged ; instead, the picture of the urinary nitrogen 

 distribution is very similar to that obtained when carbohydrates are removed 

 from the diet. 



Conclusions 



Observations on the gaseous metabolism in experimental hyper- 

 thyroidism contirm the conclusion arrived at on other grounds, that the 

 thja^oid secretion produces an increased oxidation of carbohydrates. This 

 effect is not due to a direct stimulating effect of the thyroid secretion on 

 the oxidative processes in the cell, but follows upon its action in discharg- 

 ing glycogen from the liver. 



Two stages of experimental hj'perthyroidism can be distinguished : 

 an "early" stage in which the pre-existing carbohydrate of the food 

 and of the deposits in the organism is oxidised. When all the glycogen 

 has been removed from the liver a " later " stage sets in, in which there 

 is in addition a formation of carbohydrate from protein and possibly also 

 from fat, and a subsecjuent oxidation of the carbohydrate thus formed. 

 The " later " stage is characterised by a marked rise in the CO2 excretion 

 and the Og absorption. 



The action of the thyroid secretion on the glycogenic function of the 

 liver lies thus at the root of the increased oxidation of proteins, carbo- 

 hj'drates, and probably also of fats produced by thyroid feeding. 



Appendix. 



Protocols. 



In every case the animals were fed with 10 grm. of bread and milk 

 from 8.45 a.m. to 9.45. Food removed at 9.45 a.m. Fed again from 6 p.m 

 to 8 p.m. with bread and milk ad libitum. Food removed at 8 p.m. Esti- 

 mations of the gaseous metabolism, when made, were beg-un at 10.45 a.m. 

 and continued for the following six hours in hourly periods. 



As the main results obtained are represented graphically in figs. 1-11, 

 only the following data concerning the experimental conditions under 

 which the observations were carried out are abstracted from the protocols 

 and given here to supplement the records given in the figures. 



Rat 1. First Series.— From 5/10/14 to 15/10/14 fed as described 

 above. No observations on gaseous metabolism made. Same method of 

 feeding continued, and observations made on — 



