220 CORTEX 



thyroid substance causes an enlargement of the adrenals 513 

 which may be looked upon as secondary to the increased 

 metabolic activity. Reactions in general which cause an in- 

 creased metabolic activity are accompanied by hypertrophy 

 of the adrenal cortex. Feeding thyroid extracts to adrenalec- 

 tomized animals markedly reduces their survival period which 

 is also a specific example of the effect caused generally by an 

 increase in metabolism. 



A number of experiments have been carried out on the effects 

 of feeding or implanting adrenal tissue on the thyroid or upon 

 the metamorphosis of amphibia. 186 Such experiments have no 

 significance in determining the relation of the thyroid and 

 adrenal glands for it is doubtful if any cortical hormone was 

 being administered by the methods utilized in these inves- 

 tigations. Any observed changes are to be attributed to the 

 toxic effects of the administered tissue. 



The etiology of hyperthyroidism has been attributed to some 

 unbalance between the adrenal and thyroid glands. Ma- 

 rine's 433 demonstration of an increased thyroid activity in 

 sublethal injury to the adrenals led him to hypothecate that 

 hyperthyroidism is due to dysfunction of the adrenals. He 

 attempted, therefore, to alleviate the symptoms of Grave's 

 disease by administration of fresh and dried adrenal substance. 

 The reputed beneficent effect of this therapy is open to criti- 

 cism and more recent work has shown that administration of 

 neither cortical extracts nor fresh raw cortical tissue results 

 in any clinical improvement 664 in patients suffering from hy- 

 perthyroidism. 



Normal metabolic activity in the higher organism is depend- 

 ent upon both the thyroid and the adrenal gland. The extir- 

 pation of either gland leads to a reduced metabolic activity. 

 The effects of thyroidectomy are chronic and are not incom- 

 patible with life while the decreased metabolism which follows 

 adrenalectomy is perhaps only a reflection of the general dys- 

 function of the tissues generally. Too great emphasis should 



