50 Herring 



method, and tlie adrenalin in the latter may have perished to some extent. 

 Folin found the method very reliable. The figures given in the following 

 tables for the adrenalin content of the normal rat show remarkable con- 

 sistency. For comparative estimations of adrenalin the method appears 

 to be the most satisfactory yet devised. 



Results Obtained. 



The results of the first series of experiments are recorded in Tables I. 

 and II. Thirteen male rats were examined in each case. In weight the 

 normal animals varied from 107 to 294 grm., while the thyroid-fed rats 

 varied from 96 to 294 grm. final weight. No record is kept of any change 

 in weiofht of the normal animals, but in the thvroid-fed rats the oriijinal 

 body-weight is given in column 4, the final weight in column 5, and the 

 difference in column 0. The total weight of the suprarenals in mg. is then 

 given. The weight of the suprarenals in mg. per 100 grm. body-weight 

 is recorded in the next column. The total amount of adrenalin in mo-., 

 the adrenalin in mg. per 100 grm. body-weight, and the percentage of 

 adrenalin in the suprarenals are given in the last three columns re- 

 spectively. 



Some of the thyroid-fed animals lost weight during the experiment, 

 but the majority gained, although the average gain in the thirteen rats 

 only works out at 3 grm. The last animal of the series was a much older 

 animal than the rest, and was very fat when first taken. It lost 49 grm. 

 in 21 days, but was quite healthy when killed. No. 7 rat, which gained 

 42 grm., died suddenly on the 20th day of the experiment. Two other 

 animals, while apparently thriving and in good health, died suddenly at an 

 earlier stage and are not recorded in this experiment. The average weight 

 of the normal rats in Table I. is 192 grm., that of the thyroid-fed rats 

 171 grm., showing a difference of 21 grm. 



The second series of experiments is recorded in Tables III. and IV. In 

 these the length of each animal, taken from tip of nose to anus in a 

 straight line, is recorded in column 7. This measurement is an important 

 one in Donaldson's statistics, and is correlated in his tables with the 

 age, weight of body, and weight of organs of the animal. The animals in 

 this series were rather under three months old when killed, and a^ree 

 fairly closely in age, length, and l)ody-weight with the corresponding- 

 normal animals of Donaldson's. The thyroid-fed animals received in 

 their diet 0*2 grm. fresh ox thyroid daily. This amount seems to have 

 retarded slightly the growth of some of them. The thyroid-fed animals 

 gained an average of 62 grm. in body-weight in from 23 to 26 days, 

 while the control animals, which received in their diet 0*2 grm. fresh 

 ox flesh daily, gained an average of 70 grm. during the same period. 

 Both sets started with the same average weio;ht ; the heaviest rat. 

 No. 3 of the thyroid-fed ones, retained its position throughout the 



