LIVER OF BIRDS. 177 



lobe has its hepatic artery and vena portae. The hepatic arteries 

 are proportionally small, but the portal veins are of great size, 

 being formed not only by the veins of the intestinal canal, pan- 

 creas, and spleen, but also by the inferior emulgent and sacral 

 veins. The blood, which has circulated in the liver, is returned 

 to the inferior cava by two venae hepaticse. There are occasionally 

 some smaller hepatic veins in addition to the two principal ones. 

 The coats of the portal and hepatic veins appear to be equally 

 attached to the substance of the liver. A duct arises by two 

 roots from each lobe, and the biliary secretion is carried out of the 

 liver by these two and sometimes by three ducts ; one duct always 

 terminates directly in the intestine, and is an ' hepatic duct,' 

 fig. 87, n, n\ the other enters the gall-bladder, and is an * cyst- 

 hepatic duct,' ib. o' ; the cystic bile is conveyed to the duodenum 

 by a ^cystic duct,' ib. o. Where, as in a few instances, the gall- 

 bladder does not exist, both hepatic ducts terminate separately in 

 the duodenum, fig. 85, n, n ; but in no case is there a single 

 ductus communis choledochus as in Mammalia. 



The galUhladder, fig. 87, p, is situated near the mesial edge of 

 the concave or under side of the right lobe, and is commonly 

 lodged in a shallow depression of the liver ; but sometimes, as in 

 the Eagle, Bustard, and Cormorant, only a very small part of the 

 bao; is attached to the liver. It has no visible muscular tunic : 

 its inner surface is delicately reticulated. 



The gall-bladder is present in all the Raptoi^es, Insessores, and 

 Natatores. It is wanting in a great proportion of the Scansores, 

 as in the genus Rhamphastos and in almost all the Psittacidce and 

 Cuculidce. Among the Rasores the gall-bladder is constantly 

 deficient in the Columbidce or Dove-tribe alone, in Avhich the 

 coeca are shorter than in any other vegetable feeder. The gall- 

 bladder is occasionally absent, according to the French Acade- 

 micians,^ in the Guinea-fowl ; and they also found it wanting in 

 two out of six Demoiselles (Anthropoides Virgo). The gall-bladder 

 is small and sometimes absent in the Bittern : I found it absent in 

 one out of three Kivis (^Apteryx) : it is always wanting in the 

 Ostrich, but is present in the Emeu and Cassowary. 



The bile, as before observed, passes directly into the gall- 

 bladder, and not by regurgitation from a ductus choledochus ; 

 the cyst-hepatic duct arises from the right lobe, and is continued 

 in some birds alono* that side of the bao^ which is in contact with 

 the liver, where it penetrates the coats of the cyst and termi- 

 nates about one-third from the lower or posterior end. In the 



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