NERVOUS SYSTEM UPON SECRETION 281 



most important efferent channel for reflex stimulation of the gastric 

 secretion, these experiments demonstrate the most important fact 

 that the profound and fatal effects of double cervical vagotomy 

 carried out at one operation are due to the sudden shock of complete 

 removal of vagal control upon the heart, respiratory, and alimentary 

 systems, and that compensation can and does occur and prevent the 

 fatal result, if the operation be carried out piecemeal. 



Although sham feeding calls forth reflexly no flow of secretion 

 after the vagal fibres have been completely severed, it must not, 

 however, be hastily assumed that no secretion can occur under 

 any circumstances after the vagal fibres have been so thrown out of 

 action, for both Pawlow and other observers have observed secretion 

 under such conditions. Whether such secretion is due both to 

 stimulation through other nervous channels, such as the sympathetic 

 fibres, or to absorption of chemical substances which cause direct 

 chemical stimulation of the gland cells, may still be disputed. 

 Recent work shows that such direct chemical action upon the cells 

 is a cause of secretion. 



Effects on Gastric Secretion of Stimulation of the Peripheral End 

 of the Severed Cervical Vagus. The experiment of vagus stimulation 

 yields results entirely confirmatory of those obtained by section 

 of the nerve, but similar preliminary precautions are necessary. 



After gastrotomy and oesophagotomy have been previously 

 carried out as before described, one vagus (the right) is cut through 

 as before below the cardiac and laryngeal branches, then the other 

 vagus is cut through in the neck, and after a length has been dis- 

 sected out and attached to a ligature it is left in situ, and the wound 

 closed up for a period of three to four days. The stitches are then 

 carefully removed, exposing the nerve for stimulation, and this 

 is stimulated with slow rhythmic induction shocks at intervals 

 of one to two seconds. A secretion of juice is invariably obtained 

 from the empty stomach as a result of such stimulation. The 

 object of waiting for three or four days after section of the vagus 

 is to allow time for the cardiac fibres to degenerate, which process 

 appears to occur earlier than the degeneration of the secretory 

 fibres of the stomach. 



After obtaining positive results regarding the efferent function 

 of the vagus in gastric secretion by this so-called " chronic" method, 

 Pawlow and his co-workers returned to the attempt to obtain 

 evidence by the so-called " acute " method of stimulation of the 



