Chap. XIV.] THE EARTHWORM. 285 



(2.) The red fluid (pseudhsemal fluid) is contained in a definite 

 system of vessels. 



The typical arrangement in segments, posterior to the twelfth, 

 seems to be as follows : 



1. The dorsal vessel running above the alimentary canal gives 

 off, on either side 



2. Commissural vessels of two kinds 



(a.) Intestinal, two or sometimes (1) three in each segment, 

 which break up into capillaries on the walls of the 

 alimentary canal or in the " hepatic " tissue ; 



(b.) Lateral, one in each segment, to the septa and muscles 

 of the body-wall, and thus to the subneural. 



3. Sub-intestinal vessels; a pair of closely-connected longi- 

 tudinal vessels lie one above the other, between the alimentary 

 canal and the nerve-chain. The superior collects red fluid from 

 the intestinal walls, the inferior gives off vessels to the seg- 

 mental organs. 



4. A sub-neural vessel, lying beneath the nerve-chain, collects 

 blood from the body-walls and septa, and from the segmental 

 organs. 



5. Delicate latero-neuml vessels run one on each side of the 

 nerve-chain, and give off branches along the nerves. 



From the sixth to the eleventh segments single commissural 

 vessels pass from the dorsal to the single sub-intestinal vessel. 

 These commissural vessels are enlarged to form so-called hearts. 



In the twelfth segment the commissural vessels do not reach 

 the sub-intestinal, but bend forwards and become lateral vessels 

 running forward along the oesophagus. 



In the first six segments, the dorsal, the sub-intestinal, and 

 these lateral vessels branch out to form a net-work over the 

 pharynx. 



In the " hearts "the contraction is from above downwards. 

 But it would seem that, elsewhere, there is no definite circula- 

 tion of red fluid in one direction. Not improbably it is forced 

 hither and thither during the alternate contraction and exten- 

 sion of the body. 



