436 FUNCTIONS OF THE SENSORIUM COMMUNE, [ch.iv. 



der the nerves -whicli arise from tliem independent of the will, 

 and therefore that the heart and intestinal canal are not subject 

 to volition, since they receive their nerves from the ganglia of 

 the intercostal [great sympathetic] nerve. Tissot thinks, that 

 the doubts advanced by Haller, and more fully entered into by 

 Haase, are not at all unanswerable, and are indeed of that cha- 

 racter, that they may be easily made to comport with the doc- 

 trine of Johnston. Pfeffinger has also studiously investigated 

 this theory as to the uses of the ganglia, and approved of it in 

 an elegant dissertation, ^De Structura Nervorum,^ published 

 in 1782. 



It is not an improbable conjecture, therefore, that the 

 ganglia found around the nerves act as a sort of gentle ligature 

 or compress, so that the connection between the two extremities 

 of a nerve is so far interrupted, as to prevent the impressions 

 made on the one extremity of the nerve being communicated 

 through the ganglion to the other extremity ; yet the com- 

 munication of all impressions is apparently not altogether 

 interrupted; for if they be powerful, they appear to pass 

 through the ganglia, and to be transmitted forward along the 

 length of the nerves, but with broken and diminished force. 

 From this it appears to be possible to understand, why the 

 mind has no immediate control over the movements of the 

 heart, stomach, and intestines, namely, because the impressions 

 made by the will on the origins of the nerves do not appear to 

 pass through the ganglia of the intercostal, or great sympathetic 

 nerve, to the parts mentioned, which derive their nerves princi- 

 pally from the intercostal. For this reason it also appears, that 

 although, when the medulla spinalis is irritated, all the muscles 

 are spasmodically contracted, yet the movements of the heart, 

 stomach, and intestines, are scarcely, if at all, accelerated, since 

 the impression of the stimulus applied to the medulla spinalis 

 cannot be transmitted to the intercostal [great sympathetic] 

 nerve through its ganglia. But eminent men testify, that they 

 have seen the motion of the heart increased, and the heart when 

 at rest excited into action by irritation of the medulla spinalis, as 

 also certainly that from too great emotion, — anger, for example, 

 — the hearths action is immediately accelerated ; whence it neces- 

 sarily follows, that the impressions of a stimulus from the brain 

 and spinal cord may pass through the ganglia of the intercostal 



