THE FROG AND VERTEBRATES IN GENERAL 183 



Lying in the anterior end of the coelomic cavity, just below the 

 sternum, is the heart. It is enclosed in a delicate, transparent 

 membrane, the pericardium. On either side of the heart, and 

 extending posteriorly for a considerable distance, are the brownish- 

 colored lobes of the liver which is one of the most prominent 

 organs in the abdominal cavity. It consists of three main lobes 

 connected by small tubes, the hepatic ducts, which communicate 

 with a common gall bladder. The latter can be noted as a small, 

 green sac lying between and slightly dorsal to the lobes of the liver. 

 The pair of thin-walled lungs can be seen lying posterior to and 

 on either side of the heart. (W. fs. 107, 112.) 



Projecting posterior to the liver, the stomach can be seen. The 

 anterior, cardiac portion merges without very great differentia- 

 tion into the esophagus which leads to the mouth. The poste- 

 rior, pyloric portion of the stomach is somewhat smaller than the 

 cardiac portion. It ends at a definite constriction, the pylorus, at 

 which point the coiled small intestine begins. The first loop of 

 the small intestine curves anteriorly and, together with the pyloric 

 end of the stomach, forms a U-shaped structure, between the two 

 sides of which the important digestive gland, the pancreas, is 

 situated. The latter is an elongated, yellowish body. The com- 

 mon bile duct from the gall bladder passes through the pancreas, 

 the ducts of which it receives, and then opens into the small intes- 

 tine near the anterior end. The small intestine can be traced 

 posteriorly, through a number of coils, to where it enlarges to form 

 the large intestine, or rectum, which merges into the cloaca. 

 The latter opens to the exterior. Lying near the anterior end of 

 the rectum, a small, reddish body, the spleen, is to be seen. The 

 stomach and intestines are suspended in the coelom by membra- 

 nous sheets, known as mesenteries, which surround the walls 

 of the intestines, and which are also continuous with the layer, 

 termed the peritoneum, which lines the coelom. (W. fs. 107, 112.) 



The urogenital system, consisting of the kidneys, bladder, 

 gonads, and associated ducts, lies near the dorsal wall of the coe- 

 lom toward the posterior end. There is a pair of elongated, brown- 

 ish-colored kidneys, one of which lies on either side of the coelom. 

 On the ventral surface of each kidney is a thin strip of orange- 

 colored tissue, the adrenal body. The adrenals are among the 

 most important of the ductless glands, and give off an essential 

 secretion directly into the blood. A very small duct, the ureter, 



