136 G. K STEWART 



the circulation from the suprarenal gland. The nictitating membrane 

 may also be retracted. When the experiment is repeated after removal or 

 ligation of the suprarenal, there is either no dilatation of the pupil or a 

 very slight one. It was demonstrated by Stewart, Rogoff and Gibson that 

 the latent period of the liberation of epinephrin from the glands on stim- 

 ulation of the splanchnics is so short that the time interval after which 

 the eye response occurs is sensibly the same, whether it is evoked by 

 splanchnic stimulation or by the injection at the level of the suprarenals 

 of a quantity of "adrenalin" sufficient to elicit a response similar in 

 character and amount. The minimum period of stimulation of the 

 splanchnic needed to liberate sufficient epinephrin to elicit a response in 

 the denervated eye is very brief (a fraction of a second). .Anything which 

 interferes with the passage of the blood from the suprarenals to the eye 

 during stimulation of the splanchnic, e.g., clipping of the inferior cava, 

 hinders the response, which, however, is obtained when, after stopping 

 stimulation, the obstruction to the passage of the blood is removed. The 

 demonstration is complete that the eye reactions are due to augmented 

 epinephrin liberation under the influence of stimulation of the splanchnic. 



That the spontaneous output is entirely under the control of nerves 

 is well established. The best proof is furnished by the quantitative esti- 

 mation of the output before and after section of the splanchnics and other 

 efferent paths carrying the secretory fibers. It has been shown (Stewart 

 and Rogoff (e) 1917, 1919) that the output may be reduced (in the cat and 

 dog) so much that no epinephrin could be detected in the suprarenal vein 

 blood even when segments sensitive enough to detect 1/1,000 of the 

 normal output were employed. In a macaque monkey no epinephrin 

 could be detected, although the segment gave a distinct reaction with 

 1 :88(),000,000 "adrenalin," and the output could not have been 1/100 

 of the normal. 



Although the bulk of the efferent epinephrin secretory fibers run 

 in the major and minor splanchnic nerves, there is evidence that 

 some of the fibers may pass from the abdominal sympathetic chain to the 

 glands. For after section of the splanchnics a detectable, though much re- 

 duced, output of epinephrin may be observed (in the cat and dog). There 

 is probably some variation in different individuals in this regard. Fur- 

 ther, it has been shown by Elliott (e) (1912) (in cats) that the store of 

 epinephrin in the suprarenal is only fully protected against depletion 

 under the influence of anesthesia and other conditions, if all the fibers 

 coining to the semilunar ganglion are cut. And, as will be pointed out 

 later, the most satisfactory hypothesis of the depletion produced by some 

 drugs at least, such as ether, is that the formation or the storage of 

 epinephrin in the suprarenals is interfered with while the spontaneous 

 discharge, which is strictly under the control of the nervous system, goes 

 on steadily in the case of the gland the nerves of which are intact, but 



