52 



Herring 



weight of the suprarenals varies from 37 to 60 mg., the 



average 



for the 

 thirteen rats being 46 mg. as against 29 mg. in the normal. The difference 

 is even more pronounced when the weights per 100 grm. body-weight 

 are compared. In the normal animals the average weight of the supra- 

 per 100 grm. 



renals per 100 grm. body-weight is 15'1 mg., while in the thyroid-fed 

 rats it is 26'88 mg. The difference is 11*78 mg., giving an increase in the 

 thyroid-fed rats of 78 per cent. 



Table IL— First Series. 



Rats fed on Bread and Milk +0-5 Grm. Fresh 

 Ox Thyroid daily. 



In the second series tlie same effect is noted. The suprarenals of 

 the thyroid-fed animals vary from 82 to 60 mg. in weight, the average 

 being 41 mg. compared with the average of 25 mg. in normal animals of 

 the same age. Per 100 grm. body-weight the figure for the thyroid-fed 

 animal is 30*38 mg. compared with 17*27 mg. in the normal of this series. 

 This is an increase in weight of the suprarenals of the thyroid-fed animals 

 of 13*11 mg. per 100 grm. body- weight, or nearly 76 per cent. 



In the first series of older animals the increase is 78 per cent. ; in the 

 second series of young animals the increase is 76 per cent. This increase in 

 the weight of the suprarenals estimated per 100 grm. body- weight appears 

 to result from feeding the animal over a period of from 20 to 30 days 

 with small doses of fresh ox thyroid. The increased size in the thyroid- 

 fed animal is at once apparent when the suprarenals are exposed. The 

 increase appears to be partly of cortex and partly of medulla. 



