Activities of Center of Deglutition. 109 



impulse from section to section within the center of deglutition. 

 The occurrence of efficient initial acts of deglutition and the 

 presence of the secondary peristalsis testify that during this 

 early stage the local reflexes within the center controlling the 

 primary act of deglutition and the secondary peristalsis are little 

 affected. This is in harmony with the fact that the mechanism in 

 control of the two mentioned local reflexes are more resistant to 

 anesthesia than the mechanism which controls the primary peris- 

 talsis. In the second phase also the local reflexes, controlling the 

 secondary peristalsis, are abolished, while the initial act of deglu- 

 tition is still fairly active. In this phase stimulation of the vagus 

 causes a fairly good contraction of the esophagus. The facts ob- 

 served during this phase permit the following two conclusions: (I) 

 That the inhibitory action of magnesium in this phase is exerted 

 essentially on the center and but little, if any, upon the motor nerve 

 endings, and (2) that the local reflex of secondary peristalsis, which 

 comes only occasionally into play, is more readily affected than the 

 local reflex of the mechanism of the initial act of deglutition which is 

 frequently in action and which has to be of a stable and resistant 

 character. In the third phase, when the initial act of deglutition 

 is also abolished, the inhibitory action of magnesium is probably 

 exerted upon the center as well as upon the motor nerve endings. 

 For our present purpose, however, it is of no interest to us to 

 analyze the conditions prevailing during this phase. 



The chief results of our experiments, so far as the action of 

 magnesium is concerned, consists in the following conclusions: 

 that a graded intravenous injection is capable of causing a com- 

 plete central depression of the mechanism of deglutition before a 

 peripheral effect can be ascertained; that the transmission of 

 impulses from section to section within the center is more readily 

 affected than reflex actions, and that reflexes of an important 

 function in frequent action are more resistant than local reflexes 

 of an incidental character. 



