260 ELEMENTARY BIOLOGY. [CHAP. 



with the instrument as you cut, in order to avoid the 

 possibility of injuring the underlying vessels. Care- 

 fully remove the lateral body wall of the above seg- 

 ments to the level of the middle line, and without 

 dissecting further, note 



a. The supra-intestinal and supra-neural vessels, to- 

 gether with such of their branches as have been 

 already mentioned. 



Look out for the lateral-neural vessels. 



b. The sub-neural vessel, a delicate median-ventral 

 trunk, seen on raising the nervous axis, to which it 

 is closely applied. 



c. The circumoesophageal vessels (hearts so-called 

 "pseudo-hearts"}. They lie in segments 6 to u in 

 Allolobophora, 7 to 1 1 in Lumbricus, and connect 

 the supra-intestinal and supra-neural trunks. 



d. The lateral-oesopliageal vessel, a conspicuous 

 usually highly distended trunk, closely applied to 

 the wall of the resophagus on either side. Large 

 branches of it are seen on the pharynx and 

 cesophageal glands. Trace it to its connection 

 with the dorsal vessel (in Allolobophora in the 

 1 2th segment in Lumbricus in the loth). 



3. Still working from the side, carefully cut (with scissors) 

 into any three or four somitic constrictions of the 

 intestinal region, and without dissecting further ma- 

 nipulate the parts with forceps under water. Note 



