I.~ I.] THE FROG. 



Ill 



a. On the surface of the fragment and especially 

 around its edges numerous minute elevations will 

 be seen : these are the papilla : some (filiform 

 papilla) are pointed at the free end and others 

 (fungiform papilla) 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 papillse 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. 



/?. 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 septum narium; a median longitudinal par- 



