AMPHIBIA. 73 



mercury for a few days, and has had the membrane carefully detached nearly as far 

 as the spine, the fine branches proceeding from the spinal nerves may be seen passing 

 upon this membrane to a cord in some parts, and in others to a complicated plexus, 

 varying in different parts according to a prescribed law, but observing a similar 

 disposition to corresponding but varied distributions in other orders. So long, 

 however, as it preserves the form of a cord, although it has communicated with a 

 great number of spinal nerves, and does not acquire an increased size, it is sufficient 

 for the consent of all the parts supplied, but not for imparting to them the required 

 nervous influence for the performance of their functions. It therefore shows that it 

 exists for producing a sufficient sympathy between all the cerebral and spinal nerves 

 communicating with it, as well as between all the viscera ; but that the nervous power 

 each part requires rather depends on the local connections through it with the spinal 

 cord and nerves, than on any power that can be conveyed from the distant cerebral 

 nerves through such an extended prolongation without a more material increase of 

 size than is apparent. 



