Electricity and Galvanism. 245 



they would be separated by the insulating matter of Schwann. I 

 shall, however, have again occasion to return to this question. 



I dare not occupy your time by an allusion to all the hypothetical 

 notions which have been promulgated regarding the part played 

 by electricity in the animal economy ; still there are two or three 

 which, as well from their ingenuity as from the talent of their 

 authors, well deserve a passing notice. Among these, the supposed 

 action of electricity, as the agent which, by traversing the nerves, 

 induces the contraction of muscle, a theory announced by Prevost 

 and Dumas, stands foremost. It was assumed by these philoso- 

 phers that the nervous fibrillae traversed a muscle in a direction 

 perpendicular to the direction of its fibres, forming a series of loops, 

 either by uniting with each other or with a neighbouring nerve. On 

 the influence of the will being directed towards the limb, a current 

 of electricity was supposed to be transmitted along the nervous 

 parallel loops, which consequently attracted each other, and of 

 course on their approximating caused contraction of the muscle : 

 this view is evidently founded on the well known fact of currents 

 moving in the same direction attracting each other, which a single 

 experiment will easily demonstrate. 



It is hardly necessary to allude to the objections which may be 

 opposed to this most ingenious theory ; among the most serious is 

 the fact that more recent researches of physiologists have shown that 

 the views of its talented authors are not consistent with a correct 

 knowledge of the organization of muscular tissue. 



The influence of electricity as an agent in exciting the function of 

 digestion, and, indeed, enabling us to replace the vis nervosa, trans- 

 mitted by the pneumogastric nerves, by a weak current, has been 

 especially insisted upon by Dr. Wilson Philip. This very indefati- 

 gable observer made numerous observations on this matter, and he 

 succeeded in proving that when in a rabbit, which had just partaken 

 of a hearty meal, the par vagum was divided on both sides, the food 

 remained in the stomach unaltered, whilst on allowing an electric 

 current to traverse the course of the nerves to the stomach, digestion 

 was effected. This is just what might, from what is now known of 

 the nature of digestion, have been expected, and a very much less 

 energetic current than that employed by Dr. Philip would have been 



