SAXGUIFEROUS SYSTEM. 445 



its lateral branches also form regular vesicular enlargements 

 near the sides of the nervous ganglia. The lateral vessels 

 are wider than the median, their branches anastomose with 

 each other, and also with the dorsal vessel, and they appear 

 to receive the aerated blood from the respiratory vesicles, as 

 the lateral vessels receive it from the branchiae, in other an- 

 nelides. Their tapering ends are united by anastomosis 

 across the median plain, both anteriorly and posteriorly, so 

 that they form a continuous canal around the margin of the 

 body ; and their large dorsal branches^ at the posterior por- 

 tion of the body, form five long rectangular meshes by their 

 free junction across the segments. The dorsal vessel com- 

 mences posteriorly by two branches, which unite together at 

 the pyloric end of the stomach, and all the vascular trunks 

 of this animal give off or receive their branches with a sym- 

 metry equal to that of the nervous system. 



The blood is also of a deep red colour, and charged with 

 globules, in the earth-worm, lumbricus terrestris (Fig. 133. 

 C.), and from the greater transparency of the body, the 

 direction of the internal currents is more perceptible than in 

 the more opaque body of die leech, where it is necessary to 

 examine this part in very young individuals, and where the 

 currents have appeared often to change their direction through 

 the vascular trunks. Successive waves of contraction are dis- 

 tinctly seen in the earth-worm, extending from behind for- 

 wards along the wide dorsal vessel ; and by removing the in- 

 teguments and pressing this artery between the forceps, it 

 becomes empty in front and turgid behind. It appears to re- 

 ceive the arterialised blood from the air vesicles, and sends 

 off numerous lateral branches in its course, especially to the 

 alimentary canal and the genital organs. The venous blood 

 is collected from the viscera chiefly by the great median sub- 

 gastric or epi-neural vein extending backwards between the 

 digestive canal and the nervous columns; and this vessel 

 appears to send off branches to the numerous minute res- 

 piratory vesicles. A small inferior median vessel or hypo- 

 neural vein is also perceived extending along the under 

 surface of the nervous chords, and an accompanying lateral 

 branch is seen as usual on both sides of the same columns. 

 Anterior to the commencement of the stomach, the great 

 dorsal artery, (133. C. b. b.) communicates with the median 

 subgastric vein, (133. C. a. a.) by five or more pairs of lateral 



