20 Philip on the Eighth Pair of Nerves. 



such effect either oh venous blood, namely, that which has 

 already undergone the effects of the secreting power, or on ar- 

 terious blood, which has lost the vital principle. I need not 

 here refer to the well-known facts of electricity being evidently 

 conveyed by the nerves and Under the power of the will in 

 certain animals, and the newly dead brain forming, with other 

 parts of animals, a galvanic apparatus. 



It has been said that the restored digestion and free breathing 

 produced by the influence of the voltaic battery after the inter- 

 ruption of the nervous influence, may arise from the former 

 acting as a stimulus to the secreting surfaces ; but it will appear, 

 I think, that this explanation which is derived from the laws of 

 the muscular system, is founded on a false analogy. It is 

 proved, by the most simple experiments, that after the nerves 

 of a muscle have been divided, the application of a stimulus 

 still calls it into action ; the cause of which is explained 

 by those experiments which prove that the muscular power 

 is independent of the nervous system, and only affected 

 by its influence in the same way as by other stimuli. But with, 

 respect to the secreting power, all the experiments on the subject 

 combine to prove that it so immediately depends on the nervous 

 system, that it ceases to exist as soon as the influence of that 

 system is withdrawn. 



It maybe proper to add, that the experiment which proves 

 that the division of the nerves only destroys the secreting power 

 when one portion of them is folded back^ is an experimentum 

 crucis respecting the subject of my late discussion with Dr. 

 Alison. It appears from it, that it is not the injury done to the 

 nerve, but the interruption of the nervous influence, which 

 destroys the secreting power. 



Mr. Field found that an opening made in the trachea of a 

 horse, large enough freely to admit of the introduction of two 

 fingers, had no effect in relieving the dyspnoea occasioned by 

 division of the eighth pair of nerves. 



