554 Messrs. Cramer and Krause. Carbohydrate [June 10, 



given below. In all our estimations Pfliiger's method was used, the sugar 

 after hydrolysis being determined by Bertrand's method. Unless otherwise 

 stated the last dose of thyroid gland was given 24 hours before the animal was 

 killed. In almost every case the liver of a thyroid-fed rat and that of a 

 normal control rat were subjected to analysis at the same time. Both animals 

 were kept on the same diet, both were fed at the same time, the amount of 

 food taken being noted, both were killed simultaneously (by breaking the 

 neck) a definite number of hours after a meal, the number of hours varying 

 in different series of experiments. Such control estimations are particularly 

 important in the case of the rats, since it has been shown* that in these 

 animals the liver both forms and loses its glycogen more rapidly than the data 

 given for larger animals would lead one to expect. All the animals examined 

 took their food well and showed no signs of ill health. 



The results obtained with rats, which are grouped together in Table I, were 

 tested and confirmed by experiments on cats. These animals were also kept 

 on a carbohydrate-rich diet (porridge and milk) and fed for one or two days 

 repeatedly with fresh thyroid gland. Here, too, control estimations with the 

 liver of normal cats were made in every case. Here, too, only a trace of liver 

 glycogen was found in the thyroid-fed cats, except in one case, in which 

 - 37 per cent, of glycogen was found, a value considerably lower than those 

 of the controls. By dissolving the total glycogen obtained from the whole 

 liver in the other cases in a suitable small volume of water it was hoped 

 to obtain sufficient material for a quantitative estimation, but even then 

 the reduction was so slight that the amount of sugar present could not be 

 determined. Examination of the urine contained in the bladder showed 

 the absence of reducing sugar. The results of the observations on cats are 

 given in Table II. 



In a few experiments on rats the effect of a single administration of thyroid 

 gland was studied (see Table III). There is then no very obvious effect on the 

 liver glycogen, which is still present in definite amounts. There may be a 

 diminution in the glycogen percentage of the liver and, in fact, in the few 

 observations recorded in Table III the values found for the liver glycogen 

 after one single administration of thyroid gland are below those of the control 

 animals. But since the liver glycogen varies within wide limits, even in 

 normal animals kept under similar conditions, a very extensive series of 

 observations would be necessary in order to determine whether a single 

 administration of thyroid gland is capable of affecting the liver glycogen. 

 There is further the fact that individual differences exist in the activity of 

 glands obtained from different animals even of the same species. This factor 

 * Cramer and Lochhead, ' Roy. Soc. Proc.,' 1913, B, vol. 86, p. 302. 



