CESOPHAGEAL NERVES 541 



twenty to two hundred and forty in the minute, and the number of 

 respirations fell from twenty-four to four or six. In ten days the pulse 

 and respirations had become normal. The dog was then killed by 

 section of the medulla oblongata and reunion of the divided ends of the 

 nerves was found to be nearly complete. 



Effects of Faradization of the Pneumogastrics on Respiration. Fara- 

 dization of the pneumogastrics in the neck, if the current is sufficiently 

 powerful, arrests respiration. This arrest may be produced at any time 

 with reference to the respiratory act, either in expiration or inspiration, 

 although it is more readily effected in expiration. During the passage 

 of the current, the general movements of the animal also are arrested. 

 Although respiration may always be arrested in this way, quite a power- 

 ful current is required. During the passage of a very feeble current, 

 the respirations are accelerated. They are then retarded as the current 

 is made stronger, until they finally cease. 



The following are the phenomena, observed by Bert, during the 

 passage of a powerful faradic current : 



" If an excitation is employed sufficiently powerful to arrest respira- 

 tion in inspiration, all respiratory movements may be made to cease at 

 the very moment when the excitation is applied (inspiration, half- 

 inspiration, expiration), either by operating on the pneumogastric, or 

 operating on the laryngeal. . . . 



"Any feeble excitation of centripetal nerves increases the number 

 of the respiratory movements ; any powerful excitation diminishes 

 them. A powerful excitation of the pneumogastrics, of the superior 

 laryngeal, of the nasal branch of the infraorbital, may arrest them com- 

 pletely ; if the excitation is sufficiently energetic, the arrest takes place 

 at the very moment it is applied. Finally, sudden death of the animal 

 may follow a too powerful impression thus transmitted to the respira- 

 tory centre : all this being true for certain mammalia, birds and reptiles." 



The above . expresses the most important experimental facts at 

 present known in regard to the influence of stimulation of the pneumo- 

 gastrics on respiration. The pulmonary branches themselves are so 

 deeply situated that they have not as yet been made the subject of 

 direct experiment, with any positive and satisfactory results. The 

 pneumogastrics undoubtedly are the nerves concerned in the reflex 

 acts of normal respiration. Their relations to these movements, how- 

 ever, will be considered in connection with the action of the respiratory 

 nerve-centres. 



Properties and Uses of the CEsopJiageal Nerves. The muscular walls 

 and the mucous membrane of the oesophagus are supplied entirely by 

 branches from the pneumogastrics. The upper portion is supplied 



