204 Thyroid and Liver Glycogen 
tent of the liver. Some experiments bearing upon this point 
are recorded below. 
Method.—The experiments were carried on with Rana pipiens 
in June. Desiccated thyroid, made into a paste by mixing with 
a small amount of water, was given orally. The dose of desic- 
cated thyroid was 0.5 gm., twice daily. The animals were kept 
in running tap water and no food was given to them. The con- 
trol frogs were divided into two groups. One group was kept in 
running water only. To the other group, boiled, desiccated, and 
powdered egg was fed, in quantities comparable to those of the 
thyroid given. The results are detailed in Table V. ‘ 
As shown in this table, there is no decided difference in the 
glycogen content of the livers of thyroid-fed frogs and those of 
control animals. The glycogen content of the liver of thyroid- 
fed frogs was 4.8 per cent (the average of 5 cases), while in the 
control frogs it was 4.1 per cent (the average of 4 cases). In 
none of the animals was any noteworthy change of the general 
conditions observed. Under the experimental conditions em- 
ployed, thyroid feeding does not decrease the glycogen content 
of the liver. This is in harmony with the result obtained in a 
frog poisoned with strychnine and seems to indicate a great dif- 
ference in the intensity of metabolism in the different stages of 
the life of the frog. 
SUMMARY. 
The storage of glycogen in the liver of thyroid-fed rats does 
not occur readily, even with the administration of a large amount 
of a very high carbohydrate diet. In fasted rats the liver gly- 
cogen reappears’ abundantly after ingestion of a comparatively 
small amount of food. If a sufficiently large calorific food in- 
take is administered to thyroid-fed rats, liver glycogen may 
sometimes reappear to a limited extent. The quantity of glyco- 
gen so stored is, however, much smaller than that in fasted rats, 
subsequently given food with a fuel value several times less than 
that of the thyroid-fed rats. 
The diastase content (D,n) of the normal rabbit serum and 
the normal rat liver is about 62.5 and 156 to 250 respectively. 
Thyroid feeding does not change these values markedly. 
