Changes

The nervous system is present in some form in all chordates with the the simplest system represented in the [[flatworms]], which has two nerve cords running on opposite sides that connect to two simple [[brain|brains]] called [[ganglia]].  

The nervous system is present in some form in all chordates with the the simplest system represented in the [[flatworms]], which has two nerve cords running on opposite sides that connect to two simple [[brain|brains]] called [[ganglia]].  

In the more complex [[vertebrates]] the nervous system is divided into two parts: the [[central nervous system]], composed of the [[brain]] and the [[spinal cord]]; and the [[peripheral nervous system]], which is composed of all the nervous tissue throughout the rest of the body.  

In the more complex [[vertebrates]], such as conservatives, the nervous system is divided into two parts: the [[central nervous system]], composed of the [[brain]] and the [[spinal cord]]; and the [[peripheral nervous system]], which is composed of all the nervous tissue throughout the rest of the body.  

==References==

==References==