ane J. M. D. OLMSTED 
typical cold-blooded animal—degeneration of the nerve may 
require from thirty to one hundred and forty days, depending 
upon the season of the year, although if the frog is kept at a 
high temperature (380°C.) degeneration may proceed as rapidly 
asinamammal. Also the taste buds in Amiurus which are most 
convenient for study are not on the tongue, but in the barbels, 
on the outside of the body at some distance from the mouth. 
Finally, in all the experiments on mammals the ninth nerve has 
been cut, but in Amiurus it is the seventh nerve which leads 
to the barbels. 
At the suggestion of Doctor Parker, Mr. A. J. Bigney tried 
out the operation and found that the taste buds in Amiurus did 
disappear in from ten to fourteen days. I wish especially to 
express my thanks to Mr. Bigney for turning the problem over 
to me after having gained this information. 
To learn where best to cut the nerves, a preparation was made 
by treating a freshly severed head of Amiurus with 30 per cent 
nitric acid for several hours. The skin and superficial muscles 
of such a preparation can be scraped off, leaving the nerves in 
place. The nerves are situated very close to the surface, so that 
a clean shallow cut in the skin of a living fish some 2 or 3 mm. 
in length is sufficient to disclose them. For convenience, the 
pair of barbels on the dorsal surface of the head may be desig- 
nated dorsal; those at the corners of the mouth, mandibular; 
the outer pair of the four ventral barbels, lateral, and the inner 
ones, ventral. The nerves to the dorsal barbels may be most 
favorably laid bare immediately mediad to the posterior nasal 
apertures. For the lateral and ventral barbels the cut is best 
situated 3 to 5 mm. from the base of the barbel toward the out- 
side of the fish. The nerve having been laid bare, it can then 
be freed from connective tissue, etc., so that the blade of the 
scissors may be thrust beneath it. A clean stroke of the scissors 
will sever the nerve, the stumps usually drawing back under the 
edges of the cut. If done with care and skill, the operation is 
bloodless, so that the circulation in the barbel can in no way 
be seriously interfered with. The fish may be etherized before 
operating, but better results followed when no narcotic was used; 
