TRANSVERSE SECTIONS 75 



the ventral and lateral surfaces of the cord : they are more 

 abundant in the ganglionic enlargements. 



I. The Blood-vessels. 



These are readily recognised by the deeply staining blood- 

 clots with which they are filled. The larger vessels have 

 muscular walls. Besides the neural vessels just mentioned 

 the following may be recognised. 



1. The dorsal vessel lies in the body-cavity above the intes- 



tine. It is of large size, and has masses of ' hepatic ' 

 cells at its sides. 



2. The intestinal vessels lie in the walls of the intestine : 



they are surrounded by ' hepatic ' cells, and may in 

 some sections be seen to open into the dorsal vessel. 



3. The ventral vessel Ues between the nerve-cord and the 



intestine, and is connected with the latter by a 

 median sheet of vascular connective tissue. 



