THE FROG. Ill 



a. On the surface of the fragment and especially 

 around its edges numerous minute elevations will 

 be seen : these are the papillce. : some {filiforin 

 papillce) are pointed at the free end and others 

 {fungiform papillcB) are flattened. Note the loops 

 which the blood capillaries make in many of them. 



b. Examine one of the thinner bits of the specimen 

 with a high power : a flickering motion, due to 

 the presence of cilia^ will be observed. Some of 

 the papillae however will be seen to have no cilia 

 except a narrow belt around the somewhat trun- 

 cated apex : it is on these that the gustatory discs 

 are placed, and in fortunate specimens nerve- 

 fibres can be seen entering them. 



The olfactory organ. 



The general relations of this have already been 

 described (Sects. A and E). 



a. Take a frog which has been preserved in spirit; 

 insert the point of a small pair of scissors into the 

 external nostril of one side and cut away the roof 

 of the nasal cavity. A chamber is thus exposed 

 which has a somewhat triangular form, its apex 

 being anterior. 



a. The walls of the cavity are slightly folded, and 

 there is a well-marked hemispherical eminence 

 on its floor which overlies the vomer. 



/3. The posterior nostril ; situated some distance in 

 front of the hinder boundary of the nasal sac 

 (i. e. the sac is prolonged back behind it). 



b. Open the other nasal cavity in a similar way : 



a. The septufn nariufn; a median longitudinal par- 



