PHYSIOLOGY OF EPINEPHRINE 97 



content of a cat's adrenals. Despite the great amount of 

 epinephrine discharged, the adrenal in the above cited case 

 still contained 0.14 milligrams at the conclusion of the experi- 

 ment. This indicates the rapidity with which the epinephrine 

 store of the adrenals is restored. After an hour's stimulation, 

 the epinephrine content of an adrenal may still be found to be 

 but little reduced below normal. 



Several attempts have been made to localize a center for the 

 nerves regulating epinephrine secretion, but the results of 

 different observers are discordant. Stewart and Rogoff 587 

 claimed the center to exist in the thoracic cord since section 

 of the cord at the level of the last cervical vertebra did not 

 reduce the rate of secretion of epinephrine. Elliott, 178 on the 

 other hand, found that anesthesia no longer produced a dis- 

 charge of epinephrine after cutting the spinal cord at the level 

 of the first thoracic vertebra. Removal of the brain anterior 

 to the corpora quadrigemina did not affect the secretion. 

 Elliott, therefore, concluded that the center existed at a point 

 just posterior to the corpora quadrigemina. 



The existence of a center at the base of the fourth ventricle 

 has been assumed on the basis of the results of piqure in this 

 region of the brain stem. Following piqure, a number of 

 reactions typical of epinephrine are induced. The hyper- 

 glycemia attendant on piqure is not entirely due, however, to 

 liberation of epinephrine but is in part a result of nervous 

 reflexes. 419 Stimulation of other parts of the brain stem 

 results in only slight hyperglycemia and apparently in little 

 reflex stimulation of epinephrine secretion. Stimulation of the 

 hypothalamus gives only a slight and transient hyperglycemia. 

 Stimulation of the cerebral cortex causes an epinephrine 

 secretion only when convulsions are incidentally elicited. 419 



Feldberg, Minz, and Tsudzimura 192 have recently shown 

 that a substance manifesting the pharmacological actions of 

 acetylcholine is liberated from the adrenals during splanchnic 

 stimulation. The previous injection of eserine greatly en- 



