ANATOMY OF THE GUSTATORY ORGAN 113 



cells extend only part way through the epithelium in 

 which they are imbedded. 



The foliate papillae lie on either side of the edge of 

 the human tongue and close to its root. They form a 

 series of from three to eight vertical parallel ridges. 

 Each ridge is abundantly supplied with taste-buds which, 



Fro. 26. Vertical section of a fungiform papilla showing two taste-buds. 



however, do not occur on its free outer surface but on 

 its sides. Here the buds open into the ditch between the 

 ridge on which they are located and the next one. In 

 sections transverse to the axis of the ridge the numbers 

 of taste-buds seen on the two sides of a given ditch may 

 vary from three to twenty. In the rabbit the foliate pa- 

 pillae are especially well developed and are abundantly 

 supplied with taste-buds. These have been very fully 

 studied recently by Heidenhain (1914) who has shown 

 that the buds are arranged in more or less vertical rows 

 on each papillar fold and that they probably increase 

 in numbers by a process of fission. 



The vallate papillae, which in man are usually six to 

 twelve in number, form on the posterior part of the 



