104 SEA-SIDE STUDIES. 



which lies on the dorsal, not the ventral surface. "We shall find 

 the Eolis rejoicing in a digestive apparatus as perfect as that 

 of Alderman Smith, but somewhat different in structure. 

 Stomach, properly so called, it can hardly venture to claim ; 

 for that pyriforni pouch which you observe, is rather an 

 expansion of the intestinal tube than a distinct organ. 

 Observe how this tube is continued along the whole length 

 of the body ; in some species it is wide and tapering, in the 

 one before us it is more constricted ; and be particular in 

 noticing how this tube gives off pairs of branches, which 

 again subdivide into smaller branches, and run up into 

 those club-like projections, called dorsal or branchial papilla?, 

 the cavities of which they almost entirely fill, sometimes as 

 mere dilatations, sometimes with shrub-like arborescence. 

 Having thus traced the stomach, the intestine and its rami- 

 fications, we must now look out for the next important 

 organ of the digestive apparatus, the Liver. It is useless 

 seekinfj for it ; the Eolis has not reached that stage of animal 

 development which imperiously demands a special biliaiy 

 organ ; it can transact all digestive requirements by the aid 

 of biliary vesicles scattered along the lining membrane of 

 those intestinal branches which we saw filling the cavities of 

 the papilla). In a word, we here meet with the rudimentary 

 and initial condition of the liver, nothing more than a few 

 hepatic cells. 



You understand, therefore, that these papillse covering the 

 back, and bristling up like quills upon the fretful porcupine 

 when the Eolis is irritated, are hollow tubes, containing pro- 

 longations of the intestine, and biliary cells. By many anato- 



