NERVE CUTTING IN AMIURUS 383 
more of the 6-y sections before coming to nuclei (figs. 17, 18). 
Furthermore, in the normal bud there are many more nuclei 
to a given area, since they are crowded together and have only 
a very small rim of cytoplasm about them. ‘They also stain 
more heavily than the nuclei of epidermal cells (fig. 19). In the 
two or three sections which follow, this condition is repeated 
until the capillary appears in the center (fig. 22, a). In figure 
20, b, the large wandering pigment cell represents the remains 
of a bud, and probably consists of material from the nuclei. 
This one pigment cell occupies as much space as the original 
bud, for it extends through four sections. Beneath it there is 
only a single layer of epidermal cells (fig. 22, 6), for the capillary 
appears in the next section. The removal of degenerating 
material has not proceeded so far in this case as in the other. 
There can be no question that in Amiurus the taste buds 
undergo a process of degeneration in which the leucocytes play 
the réle of phagocytes, but out of more than a hundred slides 
of barbels removed from eleven to thirteen days after cutting 
the nerve, only five or six portray the taste buds in the actual 
process of degeneration, in all others the process has not yet 
begun or has been fully completed. One must perforce conclude 
that the time consumed by this process is relatively short. I 
believe that this is the reason why neither Vintschgau nor Meyer 
got any indications of degeneration in the taste buds of the dog 
after cutting the ninth nerve, and concluded that the taste cells 
dedifferentiated into epithelial cells. They did not have enough 
material fixed at sufficiently short intervals to insure their finding 
the proper stages. 
Ranvier, on the contrary, was more fortunate in having chosen 
the rabbit for his experiment, for the rabbit is more like the cold- 
blooded animals in requiring a longer time than other mammals 
for nerve degeneration. Ranvier, therefore, happened to hit 
upon the process actually under way. The expulsion of the 
‘cover cells’ from the pore of the bud, after showing signs of 
hypertrophy, is quite comparable to the expulsion of the granular 
mass of broken-down sense cells in Amiurus, and Ranvier’s 
surmise that the large wandering cells were responsible is without 
doubt correct. 
THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 31, NO. 4 
