278 C. N. H. LONG 



Sayers suggest that the blood level of cortical hormone determines the 

 secretion of the adrenotrophic hormone, A decline in the former, pre- 

 sumably caused by the stress applied to the animal, acts as a stimulus to 

 the secretion of the latter. If the fall in the blood level of cortical hor- 

 mone is prevented by injection of exogenous cortical hormone, then 

 the pituitary does not respond. In other words a differential and tem- 

 porary hypophysectomy is achieved by this means. 



These experiments imply that stress produces conditions that cause 

 an increased rate of utilization of cortical hormone in the tissues. This 

 in turn brings about a reduction of the blood level of this hormone 

 which is the exciting factor to the anterior pituitary. Such a view is 

 perhaps half way between that of Vogt and ourselves. It regards the 

 adrenotrophic hormone as the essential factor for cortical secretion but 

 relegates epinephrine to a place with other nonspecific types of stress that 

 reduce the blood level of cortical hormones. Although our experiments 

 indicate that the stimulating effect of epinephrine on the pituitary (if 

 this exists) is abolished by raising the blood level of cortical hormones, 

 it must be remembered that epinephrine itself is a hormone with well- 

 defined points of action and is not in the usual sense "a nonspecific 

 agent." But it is also possible that the well-known metabolic effects of 

 epinephrine may cause an increased utilization of cortical hormone by 

 the tissues or change the composition of the blood passing through the 

 anterior lobe. Only further experimentation can settle these contro- 

 versial points, but I again repeat that the fact that epinephrine, by 

 whatever mechanism, increases the secretion of cortical hormone is in 

 itself a point of some importance in our understanding of the means 

 by which the organism adapts itself to stress. Indeed this observation 

 furnishes an interesting corollary to the emergency theory of adrenal 

 medullary function put forward by the late W. B. Cannon. 



Even with these points unsettled, the picture of the control of adrenal 

 cortical secretion appears at the present time to be as follows : 



(a) The changes in adrenal ascorbic acid and cholesterol may be used 

 as indicators of cortical activity. The former is probably directly related 

 to the secretion of the hormone, the latter acting as a reservoir of the 

 precursor of the hormone. 



(b) The various circumstances that increase the cortical secretion do 

 so in all probability by first activating the adrenotrophic secretion of the 

 anterior pituitary. 



(c) The manner in which anterior lobe activation is effected is either 



