PNEUMOGASTRIC NERVE. 585 



Effects of Section of the Pneumogastrics upon the Movements of the 

 Stomach. If the pneumogastrics be divided in the neck in a dog in full 

 digestion, in which a gastric fistula has been established so that the interior 

 of the organ can be explored, the following phenomena are observed : 



In the first place, before division of the nerves, the mucous membrane of 

 the stomach is turgid, its reaction is intensely acid, and if the finger be intro- 

 duced through the fistula, it will be firmly grasped by the contractions of the 

 muscular walls. When the pneumogastrics are divided, the contractions of 

 the muscular walls instantly cease, the mucous membrane becomes pale, the 

 secretion of gastric juice is apparently arrested and the sensibility of the 

 organ is abolished (Bernard). 



Notwithstanding the apparent arrest of the movements of the stomach in 

 digestion, by section of the pneumogastrics, it has been shown that substances 

 may be very slowly passed to the pylorus, and that the movements, although 

 they are greatly diminished in activity, are not entirely abolished. This fact 

 has been established by the experiments of Schiff, who attributed the move- 

 ments occurring after section of the nerves to local irritation of the intra- 

 muscular terminal nervous filaments. 



The influence of the pneumogastrics upon the general processes of diges- 

 tion, the sensations of hunger and thirst and upon absorption from the ali- 

 mentary canal have already been considered in connection with the physiol- 

 ogy of digestion and absorption. 



Influence of the Pneumogastrics upon the Small Intestine. Physiologists 

 have given but little attention to the influence of the pneumagastrics upon 

 the intestinal canal, for the reason that the distribution of the abdominal 

 branches to the small intestine, notwithstanding the researches of Kollmann, 

 in 1860, does not appear to have been generally recognized. The right, or 

 posterior abdominal branch was formerly supposed to be lost in the semi- 

 lunar ganglion and the solar plexus, after sending a few filaments to the 

 stomach ; but since it has been shown that this nerve is supplied to the 

 whole of the small intestine, its physiology, in connection with intestinal 

 secretion, has assumed considerable importance. 



The experiments of Wood have shown that the pneumogastrics influence 

 intestinal as well as gastric secretion. After section of the nerves in the 

 cervical region, the most powerful cathartics (croton-oil, calomel, podophyl- 

 lin, jalap, arsenic etc.), fail to produce purgation, even in doses sufficient to 

 cause death. The articles used were either given by the mouth, just before 

 dividing the nerves, or were injected under the skin. 



Although the observations of Wood are not entirely new, they are by far 

 the most extended and satisfactory, and were made with a knowledge of the 

 fact of the distribution of the nerves to the small intestine. Brodie failed 

 to produce purging in dogs, when both pneumogastrics had been divided in 

 the neck, after the administration of arsenic by the mouth and after inject- 

 ing it under the skin. Reid made five experiments, and in all but one, it is 

 stated that diarrhoea existed after division of the nerves. In twenty experi- 

 ments by Wood, there was no purgation after division of the nerves, in one 



