4 THE FROG 



ing from the mouth cavity. Turn the median lobe of the liver toward 

 the head and note that the stomach is continuous posteriorly with the 

 small intestine which leads to the large intestine at the extreme pos- 

 terior end of the ccelom. 



(e) If your specimen is a mature female the ovaries will appear 

 as conspicuous paired structures filled with black-and-white eggs. 

 Find the places of attachment of the ovaries and note their general 

 shape. Remove both ovaries by picking them away with your for- 

 ceps, but be careful not to injure other organs. The large black-and- 

 white eggs will be laid at the next breeding season. Observe the 

 smaller eggs by using the handlens. Estimate the total number of 

 eggs. With so many eggs in each female why has not the earth 

 become crowded with frogs? Removal of the ovaries will reveal 

 a pair of long, coiled, white oviducts stretching from the anterior to 

 the posterior end of the ccelom. Leave these in place. 



(f) If the specimen is a young or immature female the ovaries 

 will appear as paired, ruffled structures lying on each side of the mid- 

 line and dorsal to the intestine. Small eggs can be identified in these 

 organs with the aid of a handlens. Remove one of the ovaries by 

 picking it away with forceps, but do not injure other organs. 



(g) If you have a male frog the testes, a pair of small, light- 

 colored, elongated bodies, will be found by pushing the small intestine 

 aside. 



(h) The ovaries and testes are attached to the ventral surfaces of 

 the paired kidneys, which are behind the dorsal lining of the ccelom 

 (Fig. 10) . From the anterior end of the kidneys the finger-like proc- 

 esses of the yellow fat-bodies extend. On the ventral surface of each 

 kidney is a narrow, yellow band, the adrenal or suprarenal gland. In 

 immature females the oviducts will be found as slender, somewhat 

 coiled tubes running near the lateral margins of the kidneys and 

 stretching the entire length of the ccelom. In males the rudimentary 

 oviducts will be found in the same position. The spleen is a dark 

 red, round organ located in the membranous mesentery that holds the 

 small intestine in place. At the extreme anterior end of the body 

 cavity find the paired lungs covered by the right and left liver lobes. 

 At the extreme posterior end of the ccelom a thin-walled sac, the 

 urinary bladder, will be seen partially covering the large intestine. 

 If the specimen has been recently killed the lungs and urinary bladder 

 can be inflated by means of a blowpipe. 



(i) The organs in the posterior end of the ccelom should be ex- 

 posed more completely. Examine a skeleton and note the form and 

 position of the bone at the base of the hind legs. Insert the end of 



