76 EDWAED P. POULTON. 



This contact of the cells of the bulb with a tolerably ex- 

 tended surface of mucous membrane at the base is still more 

 apparent in a simpler form of bulb to be described as occurring 

 on the fungiform papillae. Another indication of simplicity is 

 the persistence of papillary elevations of the mucous membrane 

 between adjacent bulbs. This was most distinct in horizontal 

 and vertical sections of the circumvallate papillae, and was 

 especially marked at the demarcation between the lowest bulb 

 and the ordinary epithelium (of course in vertical sections). 



The great irregularity of size and shape also appears to 

 favour the view that these bulbs are of a peculiarly undeveloped 

 and ancient type. This will be further considered in the dis- 

 cussion upon the origin of taste bulbs. No very distinct 

 separation of the cells of the bulbs into central and peripheral 

 could be made out, and it is possible that this structural 

 difference is not yet established, but this suggestion needs 

 confirmation by work upon a fresher tissue. The cells of the 

 bulbs stain very slightly in carmine or hsematoxylin. Fig. 2 

 shows the structure and arrangement of the bulbs. 



Thus these circumvallate papillae in their shape and struc- 

 ture are peculiarly highly developed, notably in the abundant 

 glandular and nervous elements and the presence of nerve- 

 cells in the ganglion of the papilla. The overhanging sides of 

 the papillary body must also be regarded as marks of great 

 specialisation, carrying still further the protective function of 

 the trench. Yet combined with these extremely developed 

 structures are terminal organs of a lower type than have yet 

 been described. 



The inference is that the former structures have reached 

 their high specialisation by assisting another form of terminal 

 organ, which has been comparatively recently replaced by the 

 bulbs. This probability will be further discussed after the fun- 

 giform papillae have been considered, for these latter possess 

 structures with an important bearing on the argument. 



The fungiform papillae. — These papillae are entirely of 

 normal shape, appearance, and distribution. The only note- 

 worthy fact about their distribution is the collection into a line 



