150 J. M. D. OLMSTED 
gives the results of severing the lingual nerve and shows the 
correctness of. the supposition that the taste buds would dis- 
appear through a process of degeneration—not dedifferentiation 
or metamorphosis. 
The dogs were anesthetized, and after shaving the region 
under the jaw, a slit was made through the skin at the inner 
border of the jaw, usually on the right side. The thin mylo- 
hyoid muscle was cut through and the fascia separated so as to 
disclose the loop of the lingual nerve just peripheral to the 
branch to the submaxillary gland. This can be done with prac- 
tically no interference to the blood supply of the tongue. Only 
a small amount of bleeding takes place in the skin. A small 
piece of the nerve, about 5 mm. in length, was excised. The 
cut edges of the mylohyoid muscle and the fascia were sewn 
together with sterile gut, and some six stitches were sufficient to 
close the skin over the wound. Often the dogs began to eat 
within six hours after the operation and none of them seemed 
seriously inconvenienced, being able to move their tongues in a 
fairly normal fashion. Theré was never any infection or sup- 
puration. Swelling did occur, but this disappeared before the 
end of a week. 
When sufficient time had elapsed after an operation the dog 
was killed and the tongue removed. The taste buds on the 
anterior part of the tongue are situated on the fungiform papillae. 
These papillae occur singly and at irregular intervals over the 
surface of the tongue, being more numerous at its tip. With a 
a little care they can be recognized, especially with the aid of a 
hand lens, and removed from the tongue together with a few of 
the encircling filiform papillae. Ten or more fungiform papillae 
were taken at random from the dorsum and sides of the anterior 
half of the tongue on the side corresponding to the severed nerve, 
and also for control a similar number from the unoperated side. 
These excised papillae were fixed in Zenker’s fluid containing 
acetic acid, in formol-Zenker, or Heidenhain’s osmic-acetic-sub- 
limate mixture (Heidenhain, ’14). Sections were cut 8 y» in 
thickness. The usual haematoxylin stains were used. 
