Mouth and Tongue of the Frog. 



41 



Fungiform papilla of young 



an inch in size. The papilla receives a looped capillary, which 

 scarcely reaches beyond the point of insertion with the mem- 

 brane. No signs of nerves can be detected at this stage. Pa- 

 rallel fibrillfe of a muscular nature may be seen running outside 

 the vessels and in the same direction. The surfixce of the pa- 

 pilla is covered with small irregular cells of epithelium. (See 

 tig. 2.) The conical papilla? do not yet make Fig. 2. 



their appearance, the surface of the mem- Magnified 200 diameters. ' 

 brane being unbroken except by the fungi- 

 form bodies. The epithelial cells are indi- 

 stinct in their outline, less angular, and their 

 size not generally more than one-third of the 

 usual size in the full-gromi animal. The 

 muscular fibres over the rest of the tongue 

 are striated, the strife being more distant 

 than in the adult animal, and the fibres 

 more indistinct and much smaller. The 

 blood-globules are veiy irregular in size 

 and form; many are globular, others cres- 

 cent like, and scarcely any have attained fret- before atropiiy of tie taS. 



ii, „ T ■ j_i ■ , 1 AA. JMuscular fibre. 



tue oromary size they possess in the cc. capiiiary surmounted by 



adult ' body of the fungi- 



form papilla. 



As the tail of the tadpole becomes atrophied, the fungiform 

 papillfe increase in size ; they then assume the form they defini- 

 tively retain. At the summit of the papilla is a zone of epithe- 

 lial cells surrountbng a circular area covered with thin laminated 

 scales. The nerve of the papilla, as first seen after the complete 

 atrophy of the tail, is to be distinguished in the angle between 

 the afferent and efferent vessels by its gray colour, without any 

 signs of tubular membrane or distinct tubes. It can be traced 

 only to the concavity of the vascular loops. Fig. 3. 



In the papilla of a frog weighing about twelve Magnified 400 diam. 

 grains, we discover two or three nerve-tubes much 

 smaller than in the adult. (See fig. 3.) The 

 blood-vessels fonn several loops at the summit of 

 the papilla. Striated muscular fibres apparently 

 divested of their sarcoleinma exist. The conical 

 papiihe arc very distinct. 



In a frog weighing a drachm and a half the 

 nci've-tul>cs apj)ear more numerous, about three 

 or four in number. (See fig. 4.) The muscular 

 fibres were covered witli their sarcolcmma. The 

 striaj in tlie examples Ijcfore me were more di- 

 stinct in the longitudinal direction, while in the 

 muscular fibres not belonging to tlie fungiform 

 papilla they were more distinct in the transverse Ncrve-tuben of fungi- 



|- • - J -v.! V form pajullaol young 



direction . frog, weighing la gr«. 



