186 



BIOLOGY 



.oe 



the base of the mouth in front, and free behind. Owing to 

 this attachment, the back part of the tongue can be thrown 

 out of the mouth for a considerable distance, serving as an 

 important organ for capturing insects. Just back of the tongue 

 on the floor of the mouth is a narrow slit, the glottis, leading 

 into a tube, which passes to the lungs. Behind the glottis 



is a larger opening leading to the 

 oesophagus, and hance to the stom- 

 ach. The nostrils open in the mouth 

 through the roof in front (internal 

 nares); and a pair of openings in the 

 back part of the roof leads to the ears, 

 the eustachian openings. 



If a slit be made through the skin 

 and flesh of the abdomen, passing 

 forward on the ventral middle line 

 through the sternum, and the body 

 opened, most of the internal organs 

 can be seen. The oesophagus passes 

 directly backward about halfway to 

 the end of the body, where it ex- 

 pands into a large chamber, the 

 stomach (Fig. 90 st), which extends 

 obliquely across the body towards 

 the right. The lower part of the 

 l- d stomach is called the pylorus ; this 

 passes down into a small tube which 

 FIG. 90. THE ALIMENTARY makeg a u_ s haped bend, called the 



TRACT OF THE FROG ^fo 4 and then formg gey _ 



bl t bladder; oe, oesophagus; 



el, cloacal cavity; p, pancreas; eral COllS Which Constitute the UltCS- 



d, duodenum; sp, spleen; . 



gb, gall bladder; at, stomach; 11116, in. r inally the tube paSSCS into 



in, intestine; r, rectum. 



a large but short chamber, the rectum, 



r, which communicates with the exterior through the cloacal 

 opening. In front of and to the right of the stomach is the large 

 several-lobed liver. This secretes a liquid called bile, which 



