RELATION TO OTHER ENDOCRINES 221 



not, therefore, be placed on the superficially analogous effects 

 of extirpating the two glands on the metabolic rate. Adminis- 

 tration of thyroxin increases the metabolism far above its 

 normal, while administration of excessive amounts of the 

 adrenal cortical hormone does not influence the metabolic rate. 

 This speaks against the view that the adrenal directly controls 

 the metabolism, in the sense that the thyroid does, or that it 

 exerts a control over the thyroid as claimed by Marine's theory. 

 The metabolic activity of thyroxin is not dependent on the 

 integrity of the adrenals for a rise in metabolism can still be 

 elicited in the adrenalectomized animal by injection of thyroxin. 

 It may justifiably be argued that in such cases a sufficient 

 amount of the cortical hormone is still present in the body, for 

 in the late stages of adrenal insufficiency, thyroxin no longer 

 causes an elevation in the metabolism. 



It would seem logical to conclude, therefore, that no intimate 

 thyroid-adrenal relation exists. Injury to the adrenals or 

 their extirpation may lead to a temporary overactivity of the 

 thyroid. However, this need not be due to dysfunction of the 

 adrenals but is probably a reflex effect of trauma. Over- 

 activity of the thyroid by increasing the metabolism of the 

 organism incidentally increases the demand for the adrenal 

 cortical hormone. There is no evidence, however, that either 

 hypo- or hyperactivity of the adrenals affects thyroid activity. 

 The results of Tsuji 641 indicating hyperplastic changes in the 

 thyroid of adrenalectomized rats are of no significance since 

 his animals died so soon after operation. Mahorner 421 failed 

 to confirm Tsuji's results, in dogs. 



The relation between the adrenal medulla and its secretion 

 product, epinephrine, and the thyroid has been the subject of 

 numerous researches. Attempts have been made to ascribe a 

 close interrelation between these two organs but the results 

 are inconclusive. The increase in oxygen consumption which 

 follows epinephrine injections (Chapter VII) is elicited and, in 

 fact, accentuated after thyroidectomy. 436 The effects of 



