324 



THE VITAL FUNCTIONS. 



rated, and variously reunited in their course, like 

 a ravelled skein of thread, before they proceed to 

 their respective destinations. 



379 G 



Thus the ganglionic, or excito-raotory system of 

 Dr. M. Hall, furnish points of union between ner- 

 vous fibres belonging to various organs, which are 

 often situated very remotely from one another ; and 

 these uniting parts may be regarded as so many 

 separate centres of nervous power: the functions 

 of this system being, first, to serve as the channels 

 through which the affections of one organ may be 

 enabled to influence a distant organ ; and secondly, 

 to be the medium through which the powers of 

 several parts may be combined and concentrated 

 for effecting particular purposes, requiring such 

 co-operation. Hence it is by means of this system 

 that all the organs and all the functions are ren- 

 dered efficient in the production of a common ob- 

 ject, and are brought into one comprehensive and 

 harmonious system of operation.* 



The nervous power, the effects of which we are 



* We shall afterwards find that the greater part of the nervous 

 systems of invertebrate animals execute functions of this description : 

 not only the movements of the vital organs, but also many of those 

 of the external instruments of motion being performed apparently 

 without sensation or consciousness. 



