516 GENERAL ANATOMY. 



tions to the voluntary muscles. In the foetus it acts alone, di- 

 rects the secretory and nutritive organs, excites the energy of 

 the heart, extends its action to the animal centre, and deter- 

 mines automatic movements. In anencephalous and amyeles 

 foetuses, it excites muscular movements by its action upon the 

 spinal nerves. After birth, it acts upon the nervous centre, 

 transmitting Jo it the internal sensations, and establishes thus, 

 between the brain and the viscera of the two other cavities, a 

 connexion fertile in phenomena. At all times it rules the ac- 

 tion of the capillary vessels, and directs nutrition through the 

 intermedium of the formative or plastic power, which-this in- 

 genious writer calls vital chemistry. 



815. Almost all these opinions, which consist in consider- 

 ing the system of ganglions as an independent system, err in 

 being too absolute, as well as those which consider in the gan- 

 glions only a purely anatomical arrangement. The system of 

 ganglions ought to bq considered at the same time as a system 

 separate or united, independent or dependent, according to 

 different circumstances for the most part already indicated. 



The functions of the ganglions appear to be to diminish or 

 to arrest the influence of the nervous centre upon the gan- 

 glionary nerves, to diminish or to hinder the transmission of 

 impressions to the centre; so that by the action of the gangli- 

 ons, the vegetative nervous system is separated from the ani- 

 mal system. ' 



The ganglions appear besides to collect, to coerce the nerv- 

 ous power which they draw from the spinal marrow, to devel- 

 ope it by themselves, to communicate it conveniently to the 

 nerves and to the organs where. they terminate. 



The ganglions exercise different functions according to the 

 diversity of their texture. 



These differences consist in, lst r the mixture more or less 

 intimate of the medullary fibres; 2d, the diversity of the se- 

 condary substance; 3d, the differences in the exterior mem- 

 brane, more or less compact, more or less tense; but, it is in . 

 the ganglions of the sympathetic nerve that we observe the 

 greatest intricacy and blending of the medullary filaments, 

 the tenacity and most intimate union of the secondary sub- 



