THE PANCREAS IN BIRDS. 595 



stags. It is also absent in Solipeds and in most Pachydermata, as in the 

 horse, tapir, peccary, and elephant, but not in the pig. In the elephant, the 

 hepatic duct is dilated and thickened, and has a spiral fold within. The gall- 

 bladder is wanting, in the mice and hamsters, amongst Rodentia ; also in the 

 sloths amongst the Edentata, and in the true Cetacea. In the carnivorous and 

 insectivorous kinds, the gall-bladder is present. In the cat and a few other 

 animals, it is sometimes double. When the gall-bladder is present, a cystic, 

 hepatic, and common bile-duct exist. 



In Birds, the gall-bladder is generally present, but is wanting in certain spe- 

 cies of a particular genus, without obvious relation to its habits or food ; it is 

 absent in the ostrich, pigeons, toucans, and many parrots. Proceeding from 

 the liver, in Birds, are two ducts, one hepatic, to the duodenum, the other to 

 the gall-bladder, from which a cystic duct runs on to the duodenum ; there is, 

 therefore, no common bile-duct. When the gall-bladder is wanting, the two 

 hepatic ducts open separately into the intestine. 



In Reptiles, a gall-bladder always exists, but it varies in form. It is placed 

 at a distance from the liver and has a long cystic duct, in the Ophidians ; but 

 it is embedded in the substance of that gland in the Chelonians. There either 

 is a common bile-duct, or the cystic and hepatic ducts open separately into the 

 duodenum. 



The gall-bladder invariably exists in Amphibia. 



In Fishes, this receptacle is usually present, though it is absent in many 

 genera, being then replaced by a dilatation upon one of the hepatic ducts, which 

 are here usually numerous. 



In the Mollusca and Molluscoida. in which the liver is massive, no gall- 

 bladder is found ; nor could such a receptacle exist in connection with the he- 

 patic tubuli of the Annulosa and Annuloida. 



Pancreas. This gland, or some representative of it, is present only in the 

 Yertebrata, and in the higher Mollusca. It is not so widely distributed 

 amongst animals as the liver ; and, moreover, it much sooner assumes a rudi- 

 mentary form, in the descending series, viz., in the Fishes. 



In Mammalia, Birds, and Reptiles, the pancreas occupies the concavity of 

 the constantly present curvature of the duodenum. In Mammalia, when the 

 duodenal mesentery is short or absent, as in the Quadrumana, Carnivora, 

 Ruminants, and Solipeds, the pancreas is compact and elongated, with a por- 

 tion extending towards the spleen, so that it may seem bilobed, as in Carniv- 

 ora and Ruminantia, or even trilobed, as in the horse, the splenic portion 

 being double ; when, however, the duodenum has a wide mesentery, as in 

 Rodentia, the pancreas forms an arborescent mass between the two layers of 

 the mesentery, as seen in the rabbit and rat. 



The typical number of pancreatic ducts, in the Mammalia, appears to be two, 

 as indeed is the case in the early condition in Man, the upper and larger duct 

 alone persisting. In the horse and dog, there are also two ducts, the lower 

 one being the larger ; in the dog, this latter opens separately into the duode- 

 num, but the upper one enters it close to the bile-duct. In the lion, two ducts 

 join the bile-duct, and enter the duodenum by a common orifice. In the rab- 

 bit, the upper duct is very minute, and the chief duct opens from 9 to 12 inches 

 below the pylorus. In all cases, however, the pancreatic fluid is discharged 

 into the duodenum. In certain Carnivora, as in the seal, and sometimes in 

 the cat, the chief duct dilates into a reservoir, previously to entering the in- 

 testine. 



In Birds, the pancreas is proportionally larger than in other Yertebrata, in 

 part, perhaps, owing to the deficiencies in the salivary glands. It usually con- 

 sists of from two to six elongated portions, attached, as usual, to the much- 

 bent duodenum. Each portion of the gland has a duct, generally opening 

 separately into the intestine. There are six ducts in the vulture, fowl, heron, 

 and grebe, three in the crow, pigeon, grouse, and duck, but only one in the 

 eagle, quail, ostrich, and stork. In the stork alone, the single pancreatic duct 

 opens, by a common orifice, with a single hepatic duct. Usually, one at least 

 of the pancreatic ducts, in Birds, opens above the bile-duct, but this is not 

 constant ; when several pancreatic ducts exist, they usually open alternately 

 with other hepatic or cystic ducts ; the cystic duct generally opens lowest. 



