GANGL1ONIC NERVES. 591 



led to so many erroneous conclusions,) we learn by 

 a simple appeal to comparative physiology, that 

 the office of the ganglionic nerves is identical 

 with that of the brain, spinal marrow, and their 

 nerves. For as Cuvier truly observes, by com- 

 paring the structure and functions of different 

 species, in which " nature adds to, or subtracts 

 from, each of their different parts, just as we 

 might wish to do in our laboratories, and shows 

 herself the results of such additions and subtrac- 

 tions," we may easily ascertain the specific 

 office of any one organ. The truth is, that the 

 brain may be regarded as a large ganglion, or 

 concentration of nervous matter, of which the 

 spinal marrow is a mere continuation ; and the 

 nerves of both, as expanded branches, with 

 which the ganglions in the higher animals are 

 connected ; and the object of which is to endow 

 the involuntary organs with so much sensibility 

 as may be requisite to their well being. But as 

 the heart, stomach, and all secretory organs, 

 are excited to action by the stimulus of blood, 

 there is no necessity for their being subject to the 

 commands of the sensorium commune, like the 

 locomotive muscles, or even the sphincters of the 

 bladder and rectum. Let us then reject the doc- 

 trine of Miiller, that " the ganglia are the centres 

 of organic life," and that " the cerebro spinal 

 system alone is capable of exciting voluntary 

 motion." (Elements of Physiology, pp. 734 

 934.) 



