•^56 THE VITAL FUNCTIONS. 



his plates, represents these singular appendages 

 to the vascular system of the earth-worm, sepa- 

 rated from their attachments, and viewed in con- 

 nexion only with the dorsal and abdominal trunks 

 in which they terminate. The abdominal vessel, 

 (a, a), on arriving near the oesophagus, is dilated, 

 at the point b, into a globular bulb (c), which 

 is followed, at equal intervals, by four others 

 (c, c). From each of these bulbs, or ventri- 

 cles, as they are termed by Morren, a vessel (d) 

 is sent off at right angles, on each side ; this 

 vessel also enlarges into several nearly globular 

 dilatations (e), followed by a still larger, and 

 more elongated oval receptacle (f), which com- 

 pletes the semicircular sweep taken by the vessel 

 in bending round the sides of the body, in 

 order to join the dorsal vessel (g, g), in which 

 all the other four communicating vessels, pre- 

 senting similar dilatations, terminate. Sir E. 

 Home is of opinion that these dilated portions of 

 the vessel are useful as reservoirs of blood, for 

 supplying it in greater quantity to the neigh- 

 bouring organs, as occasion may require; but 

 Morren ascribes to them the more important 

 office of accelerating, by their muscular action, 

 the current of circulating blood. If the latter of 

 these views be correct, which the strong pulsa- 

 tions constantly visible in these bulbs render 

 extremely probable, this structure would offer 

 the first rudiments of the organ which, in all the 



