ANATOMY OF THE GUSTATORY ORGAN 115 



papilla to be 508 and 33 with an average not far 

 from 250. 



2. Comparative Distribution of Taste-buds. Taste- 

 buds, like the olfactory receptors, require a moist sur- 

 face. It is, therefore, not surprising to find that in all 

 air-inhabiting vertebrates they are limited to the oral 

 cavity. Their distribution in mammals has been very 

 fully studied by Tuckerman (1892), Miinch (1896), and 

 Haller (1909). 



Taste-buds also appear to be limited to the oral 

 region in amphibians notwithstanding the fact that many 

 of these animals possess a permanently moist skin. In 

 fishes they were apparently first seen by Leydig in 1851 

 and were subsequently described by Schulze (1863). In 

 these forms they are not restricted to the oral region. 

 According to Johnston (1906) they are present on the 

 heads of cyclostomes as well as on those of ganoids where 

 they were studied by Dogiel (1897). Herrick (1918) 

 states that in some bony fishes, such as the catfishes, the 

 carps, and the suckers they are to be found over the 

 entire outer surface of the body and this investigator 

 (1903) has further shown that in the catfish Amiums the 

 taste-buds on the flank of the fish are as significant in the 

 detection of bait as are those about the mouth (Fig. 28). 



3. General Form of Taste-buds. Taste-buds vary in 

 form from that of a flask to that of a spindle. Commonly 

 they are single bud-shaped bodies opening to the exte- 

 rior by a small pore (Fig. 29). Compound buds in which 

 the body of the bud appears double and two pores are 

 present have long been known and Heidenhain (1914) has 

 recently shown that this condition may reach an extreme 

 degree of complexity in the foliate papillae of the rabbit 



