AVES BIRDS. 



601 



In the generality of birds, however, there is only one pair of 

 salivary glands; and these, in many cases, seem to be united into a 

 single mass, separated posteriorly into two lobes, and situated 

 beneath the palatine membrane, behind the angle of the rami of 

 the lower jaw. From these glands a thick, white, and viscid fluid 

 is poured into the mouth through numerous orifices, principally 

 disposed along the mesial line, which separates the two glands. 



(670.) We have already spoken of the gastric glands which 

 densely stud the coats of the proventriculus, and furnish the "gastric 

 juice ;" and therefore pass on to notice the other subsidiary chylo- 

 poietic viscera, namely, the liver, the pancreas, and the spleen. 



The liver is a viscus of considerable magnitude, consisting of 

 two principal lobes, and firmly suspended in situ by broad liga- 

 ments and membranous processes. The vena portse, supplying 

 that venous blood from which the bile is elaborated, is formed 

 by vessels derived from numerous sources, receiving not only the 

 veins of the stomach, spleen, and intestines, as in Mammalia, 

 but likewise Fig. 273. 



the renal and 

 sacral veins ; 

 another proof, 

 if any were 

 wanting, that 

 no arrange- 

 ment by which 

 the decarbon- 

 ization of the 

 blood can be 

 facilitated has 

 been omitted 

 in the organ- 

 ization of the 

 class before us. 

 Thehepatic ar- 

 teries and the 

 hepatic veins 

 present no- 

 thing remark- 

 able in their 

 disposition, but 

 the course of the bile from the liver into the intestine merits our 



