382 J. M. D. OLMSTED 
of a hollow shell bounded by a single layer of taste cells, open to 
the outside at its distal end, and having at its base scattered 
nuclei of the sense cells, and in its center an irregular mass of 
small granules and larger globules (fig. 10). In some cases this 
hollow shell representing the taste bud was quite empty, and the 
broken-down material remained clinging to the outside of the 
barbel a short distance away. The peripheral ring of sense cells 
disappeared later, but the nuclei of the taste cells remained for 
a longer time. While the bud is still a hollow shell, epithelial 
cells appear to be pressing on its sides, closing the opening through 
which debris of the distal ends of the sense cells passed, and 
preventing the still degenerating nuclei from escaping. Phago- 
cytic leucocytes are then seen among the nuclei, and so complete 
is their disintegration that there can be no possibility of the trans- 
formation of the sense cells into any other kind of cell. The 
basement membrane beneath the bud disappears, and the space 
formerly filled with the more or less fibrillar ends of the taste 
cells, which lay beween it and the nuclei, becomes continuous 
with the capillaries of the papilla. The capillaries extend still 
further into the epidermis until they reach the region formerly 
occupied by the nuclei of the sense cells. The degenerative 
process is then complete, the indifferent epithelial cells, capil- 
laries, and wandering pigment cells now occupy the site of the 
taste buds. The degenerative process seems to be simultaneous 
throughout the whole barbel, and this appears to be true of the 
nerve also, for changes at the base of the barbel are not more 
pronounced than at the tip, and vice-versa. . 
The next step is well shown in tangential sections. The only 
indication on the surface of the barbel that taste buds were once 
present is either an accumulation of pigment (fig. 20, b), or the 
presence of three to five epidermal cells enclosed within concentric 
circles of other epidermal cells (fig. 20, a). In normal buds each 
of these whorls of epidermal cells surrounds the tips of more 
than a hundred sense cells. The next section into the barbel 
(fig. 21, a) shows a disc of twelve to fifteen epithelial cells, each 
with its characteristic round nucleus and relatively large amount 
of cytoplasm. In normal buds one must pass through five or 
