RELATION TO OTHER ENDOCRINES 219 



mized animals. 400 However, preparations free of the thyro- 

 tropic hormone have been prepared which still cause hyper- 

 trophy of the adrenals. 121 One can explain all the available 

 facts without assuming the existence of a specific pituitary 

 hormone which controls the adrenal. Nor need one assume that 

 the adrenal elaborates a separate hormone which is necessary 

 for normal hypophyseal activity; for the most highly purified 

 cortical extracts, which fail to remedy certain symptoms of 

 chronic adrenal insufficiency, are still capable of maintaining 

 in adrenalectomized animals all the physiological functions 

 attributed to pituitary activity. 



The above considerations have dealt exclusively with the 

 relation of the anterior lobe of the pituitary to the adrenal 

 cortex. Theories have also been elaborated involving an 

 assumed physiological relation between epinephrine and the 

 posterior lobe of the pituitary as well as between the latter and 

 the adrenal cortex. No valid evidence exists to substantiate 

 these assumed interrelationships and hence we need not discuss 

 them here. 



THE THYROID 



The existence of an antagonistic relationship between the 

 thyroid gland and the adrenal cortex is suggested by a number 

 of well-established observations and was clearly stated over a 

 decade ago by Marine and his collaborators. 433 Their views 

 were based chiefly on the observation that sublethal injury 

 to the suprarenal glands caused marked chronic hyperthermia 

 provided the thyroid were intact. As we have already seen 

 in Chapter XIII, this hyperactivity of the thyroid resulting 

 from adrenal injury may more reasonably be attributed to 

 operative effects, for true adrenal insufficiency is characterized 

 by a reduction in the metabolism. 



Thyroidectomy does not result in any constant change in the 

 adrenal cortex 605 nor does it always greatly affect the survival 

 period of adrenalectomized animals. The administration of 



