AND ANIMAL LIFE. 277 



of being mentioned. While the positive wire remained 

 connected with the heart, Mr KEMP was busy in applying 

 the negative to different parts of the body. He at last 

 placed it in contact with the external surface of the sto- 

 mach, which occasioned no contractions, probably from its 

 being rather dry ; but, either accidentally or intentionally, 

 he penetrated the parietes of this organ, which produced 

 violent motions of the extremities, diaphragm, and heart. 

 He inquired if there were not a nervous coat which would 

 explain the phenomenon. Mr CHESTER answered him in 

 the affirmative, and at the same moment laid it bare ; but 

 when the wire was brought in contact with this nervous coat, 

 no contractions followed its application : they returned with 

 the same violence when the wire penetrated the parietes of 

 the stomach. I proposed that the food should be exposed, 

 which was done, and when the wire was placed in the half- 

 digested contents, the motions of the extremities, dia- 

 phragm, and heart became as evident as in the first in- 

 stance. 



EXPERIMENT VI. 



Having proved, by the preceding experiments, that the 

 motions of the heart and other parts of the system could 

 be excited equally through nerves, mucous membranes, 

 veins, and the food in the stomach, I suggested a further 

 modification. The heart, after having illustrated the 

 above views for about a quarter of an hour, was entirely 

 separated from the body, and isolated by means of glass ; 

 a piece of thread was then tied to a small portion of the 

 aorta connected with the organ, and was afterwards mois- 

 tened. When the positive wire was in contact with the 

 heart, and the negative with the thread, or when reversed, 

 the contractions of the heart were again manifest. These 



