LINGUAL NERVE OF THE DOG 153 
the operated side were examined, and each possessed taste buds 
in good order, having an average of four to a papilla. 
The process by which the taste buds disappear is shown in the 
figures. One finds in many of the taste buds on the tongues of 
unoperated dogs leucocytes which resemble the large lympho- 
cytes of the blood. In a very few cases I observed polymor- 
phonuclear leucocytes within the taste bud, as in figure 2. The 
first portion of the taste bud to disintegrate is the region just 
above the nuclei of the sense cells (figs. 3, 4). This is exactly 
similar to what I found in the fish. Furthermore, the debris 
seems also to be extruded through the pore by which the taste 
bud communicates with the surface, for, as figure 5 illustrates, 
there was found at the pore of one taste bud a mass of granular 
material, evidently cytoplasmic, since it stained faintly with 
eosin, exactly similar to that inside the taste bud. Within this 
mass were two nuclei, one evidently belonging to a leucocyte. 
In the dog whose taste buds were examined on the eighth day 
after operation there were many cases of mitosis observed, in 
one instance three in a single field. In the forty fungiform 
papillae from normal dogs there was not a single case of mitosis, 
nor were there any in the neighboring filiform papillae in the 
operated dogs. ‘The final process consists in filling up the site 
of taste buds with epithelial cells (fig. 6). 
In a few cases where degeneration had evidently occurred 
recently, the boundary of the taste buds was still fairly evident 
in the form of elongated cells, as contrasted with the more or 
Fig.1 Longitudinal section through normal taste bud from fungiform papilla 
of dog. 
Fig. 2 Tangential section through normal taste bud, showing presence of 
leucocyte. 
Fig. 3 Longitudinal section through taste bud of dog whose lingual nerve 
had been cut eight days before. The area surrounding the leucocyte is entirely 
empty. The whole bud is considerably shrunken. 
Fig. 4 Longitudinal section similar to figure 3. Distal portion of taste bud 
empty except for a leucocyte and a disintegrating nucleus. The more proximal 
part is filled with granular material. 
Fig. 5 Tangential section through same taste bud as figure 4. Mass of 
granular material lying at the neck of the pore of the taste bud. 
Fig. 6 Fifteen days after operation. Taste bud indicated by arrangement 
of cells. Possible boundary indicated by broken line. 
