230 



AN INTRODUCTION TO ZOOLOGY 



the initial changes of the digestive processes. The dogfish is a 

 voracious feeder, so that the stomach is often full or even much 

 distended with food, and it frequently contains in addition an 

 enormous number of parasitic worms. 



v.o. 



H.P. 



7 , 



FIG. 73. Sketch of the arrangement of the hepatic portal factors in Scy Ilium, 

 seen from the dorsal side. The vessels were injected and the gut 

 hardened and removed whole from the body-cavity. After O'Donoghue. 



A. I., anterior intestinal vein; A.L.G., anterior lieno-gastric vein; D.A.G., dorsal anterior 

 gastric vein ; D.G., dorsal gastric vein ; D.O., dorsal cesophageal vein ; G.I., gastro-intestinal 

 vein; H.P., hepatic portal vein; /./., intra-intestinal vein; M.G., median gastric vein; P. I., 

 posterior intestinal vein ; P.L.G., posterior lieno-gastric vein ; P.S., posterior splenic vein ; 

 R., portion of posterior intestinal vein on the rectal gland; V.A.G., ventral anterior gastric 

 vein ; V.G., ventral gastral vein ; V.O., ventral oesophageal vein. 



The intestine is composed of two parts, the intestine proper and 

 the rectum. The intestine lies slightly to the right of the pyloric 

 portion of the stomach, and has the form of a fairly wide spindle- 

 shaped tube passing backwards to a point just behind the level of 

 the bend of the stomach. Into its upper end open the pancreatic 

 and bile ducts, and below this its wall is marked by more or less 



