16 THE AMERICAN MONTHLY [Jan. 



border the gallbladder can be seen. By drawing the 

 liver aside, xXxa gullet iiwxi be seen doraally to the lieart; 

 the stomach is a fusiform enlargement in the course of the 

 alimentary tube which passes insensibly into the small 

 intestine. The latter is somewhat longer than the body 

 cavity and hence is winding in its course; the mesentery 

 can be Reen clearly on its dorsal side and portal vessels ?iX% 

 recognizable. At the upper end of the small intes- 

 tine you can find the bile-duct running into it from the 

 t:nll-bhidder; and in the mesentery near by there is a dif- 

 fuhod mass of pancreatic tissue^ whose ducts open into 

 the small intestine. The large interline directly follows 

 the small intestine, is not sub-divided into parts but has 

 the form of a short rectum passing directly to the 

 cloaca. 



8. The Lungs are a pair of elongate, slender thin- 

 walled sacks; blind posteriorly, they come togetlier in 

 front and above the heart wiiere they open into a passage 

 which leads to \\\(iglottis already noted in the hinder part 

 of the mouth chamber just behind the tongue. In the 

 higher vertebrates this air tube [trachaea) is lined with 

 cartilage, but it does not appear to be so in the sala- 

 mander. The passnge can be demonstrated by passing 

 a guarded bristle down through the glottis. The lungs 

 should be cut open lo show that the interior is a very 

 simple back with only a beginning of that elaborate sub- 

 division into spaces found in the mammal. The walla 

 are reddish, this indicates the presence of blood vessels 

 in contrast with the colorless wall of the swim bladder 

 of the smelt; but to prove that the wall is vas<;ular n)ount 

 a thin film of it and examine with the compound micro- 

 scope. Do you find any blood corpuscles there? 



[This and the reptilian lung are sim})le conditions of the 

 lung of which the bird and mammal lung aie very highly 

 >,;'eciaiized conditions. The circulation and resf)iration 



