. Outlines of zoology. bacteria, parasites, and the effects of injury. If this beso, we can understand its diminishing importance in Sauropsida andMammalia, where its place may be to some extent taken by the palataland pharyngeal tonsils,- which are believed by some (Stbhr, Killian,GuUand) to have a similar phagocytic function. The pharynx leads into the gullet or oesophagus, which isa conducting tube, and this into the digestive stomach, which is followed by the diges-tive, absorptive, conductingintestine,, ending in the rectumand anus. From the oesophagus the air-or swim- bladder of most Fis
. Outlines of zoology. bacteria, parasites, and the effects of injury. If this beso, we can understand its diminishing importance in Sauropsida andMammalia, where its place may be to some extent taken by the palataland pharyngeal tonsils,- which are believed by some (Stbhr, Killian,GuUand) to have a similar phagocytic function. The pharynx leads into the gullet or oesophagus, which isa conducting tube, and this into the digestive stomach, which is followed by the diges-tive, absorptive, conductingintestine,, ending in the rectumand anus. From the oesophagus the air-or swim- bladder of most Fishes,and the lungs of higher Verte-brates, grow out. The air-bladder usually lies dorsally andis almost always single; thfelungs lie ventrally and aredouble, though connected withthe gullet by a single tube. The beginning of the intes-tine gives origin to the liver,which regulates the compositionof the blood and secretes bile,and to the pancreas, whichsecretes digestive juices. Thepancreas has often a « Fig. 266. — Origin of lungs,liver, and pancreas in thechick.—After Goette. The mesoderm is shaded; the endo derm ^ One of the lungs; stomach :l.^ liver ; p., pancreas. ALIMENTARY SYSTEM. 5° From the hindmost region of the gut, the allantoisgrows out in all animals from Amphibians onwards. InAmphibians it is represented by a cloacal bladder; in thehigher Vertebrates it is a vascular foetal membrane con-cerned with the respiration or nutrition of the embryo, orboth.
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Keywords: ., bookcentury1900, bookdecade1910, bookidcu3192, booksubjectzoology
