34 



APPLIED BIOLOGY 



stomach ? Notice that the food in the intestine is more liquid than 

 the food in the stomach. Also notice that by the time food has 

 passed along the posterior part of the intestine its bulk has been 

 greatly reduced the stomach's capacity is much greater than that 

 of the intestine. Evidently the greater part of the food disappears 

 as it passes along the stomach and mtes- 

 tine. Where does it go ? 



In addition to the parts of the food- 

 tube, the liver and the pancreas must be 

 considered alimentary organs, because 

 they form or secrete substances needed 

 for preparing foods in the intestine. 



The liver, whose position has been al- 

 ready noticed, consists of two lobes, the 

 lobe on the left side of the body being the 

 larger and subdivided into two parts. 

 Notice a small sac, the gall-bladder, be- 

 tween the right and left lobes. The 

 greenish-colored fluid which fills the gall- 

 bladder is the bile, which is manufactured 

 by the liver and stored in the gall-bladder 

 until it is needed in the intestine. A bile- 

 duct (very small and difficult to see) leads 

 from the gall-bladder to the intestine. 



(D) The pancreas lies between the 

 stomach and intestine. It is an irregularly 

 lobed mass of light color in fresh speci- 

 mens. It secretes a fluid (pancreatic juice) 

 used in digestion of foods. Many of its 



FIG. 8. Alimentary canal of sma11 ducts P en into the bile-duct, which 

 frog. <e, esophagus ; m, extends along the pancreas on the way 

 stomach ; du, d, small in- from the gall-bladder to the intestine, 

 testine ; py, pylorus ; mz, Cut the attachment of the liver, esoph- 



fc&^blad'de 1 ^ 6 Z^d*!^ ' agUS ' and intestine and remoy e these or- 

 (From ^Ecker ) ' *" ans ' t ^ lus exposing other organs nearer 



the dorsal part of the body-cavity. 



(D) The lungs are two thin-walled sacs, which, before removal of 

 the liver, were dorsal to that organ. Cut through the articulation of 

 the jaws so as to allow the mouth to open widely, and demonstrate 

 the slit-like glottis in the pharynx just ventral to the opening of the 

 esophagus. The tube into which the glottis opens is the windpipe 

 or trachea, which has two branches leading to the lungs. Insert the 



