SAND WORM 97 



The digestive tube should be removed to expose the nerve 

 cord, which is present on the ventral body wall as in the 

 earthworm. Compare the cord with that of the earth- 

 worm. Are ganglia present? Describe the arrangement 

 and distribution of ganglia and nerves. Is there a com- 

 missure about the pharynx and a brain or cerebral ganglia 

 on the dorsal side? 



On account of the numerous sense organs on the head 

 the brain is larger and there are more nerves coming from 

 it than in the earthworm. The brain lies very close to the 

 surface and is difficult to expose without injury. 



Make drawings to represent the various internal systems. 



