156 ORGAN OF TASTE. 



above, in chloride of gold. Half an hour's steeping in half 

 per cent, solution is sufficient ; but it is necessary, before ex- 

 posing the preparation in water, to stream it thoroughly with 

 the same liquid, in order to avoid the subsequent formation of 

 colored deposit on the surface. As soon as the tongue has 

 assumed the proper color, it must be hardened in alcohol, for 

 the preparation of sections which must be prepared in glycerin. 

 In vertical sections of fungiform papillae the following parts 

 are seen : In the axis of the papilla, along with the vessels, a 

 nerve twig is observed, consisting of medullated fibres, which 

 ascends towards the summit of the papilla, and there pencils out 

 into nerve fibres. Each of these is seen eventually to end in a 

 non-medullated fibre. Along the border of each papilla are 

 seen muscular fibres which divide dcndritically as they ascend. 

 The covering of the flattened summit consists of a relatively 

 thick layer, in which two strata can be distinguished. The more 

 superficial of these is thicker and paler, and is finely striated 

 in the direction of the long axis of the papilla. In thin sec- 

 tions it can be recognized that this material consists of pale 

 longitudinally striated cylinders. The deeper and thinner 

 stratum consists of a ground-substance deeply stained both by 

 gold and carmine, in which several Layers of nucleus-like struc- 

 tures are embedded. It can be made out in very thin sections 

 (and also in teased preparations) that the cylindrical nucleated 

 cells take part in the formation of both layers, the outer seg- 

 ment of each cell contributing to form the outer stratum, the 

 other, which contains the nucleus, the inner stratum. The 

 outer segment of each cell is pale and finely streaked longitu- 

 dinally, while the inner segment, which consists of granular 

 protoplasm, is divided towards the papilla into branched pro- 

 cesses, which unite with each other and with those of neighbor- 

 ing cells. In preparations successfully stained with gold, it 

 can further be made out, that the non-medullated fibres re- 

 solve themselves into a network of extremely fine fibrils, which 

 spread under the stratum of cells. No connection, however, 

 has been demonstrated to exist between this network and the 

 anastomosing branched processes above mentioned. The forms 

 of the cylindrical cells should be also studied in teased prepara- 

 tions. Strips of fresh mucous membrane are placed in the 

 dark for from twenty-four to forty-eight hours, in one-tenth 

 per cent, solution of perosmic acid. The object having been 

 steeped in water one or two clays, shreds must be torn off the 

 free surface of each strip of membrane, with fine sharp needles. 

 Each of these shreds, having further been teased carefully with 

 needles, must then be mounted in a drop of acetate of potash. 

 Another method consists in macerating similar strips in iodized 

 serum, solution of bichromate of potash, or very dilute solution 



