270 
BULLETIN OF THE UNITED STATES EISH COMMISSION. 
ADDENDUM. 
During the winter and spring of 1903 some further observations have been 
made with the purpose of answering (among others) the question raised above, 
whether fishes can localize a sensation received by the terminal buds alone with 
no tactile accompaniment; or, in other words, whether gustatory sensations may be 
provided with a local sign as tactile sensations are. (This question, of course, does 
not necessarily involve the more general one as to the essential nature of the local 
sign, whether it is due to a “specific energy” of the peripheral nerve or sense organ 
or to central differentiation in the terminal nucleus.) 
Some recent clinical observations suggest that in human beings such a localiza- 
tion of gustatory sensations is possible. Cushing (Johns Hopkins Hospital Bulletin, 
vol. xiv, No. 111. 1903, p. 77) reports after destruction of the Gasserian ganglion 
and total paralysis of general sensation on the anterior part of the tongue, that the 
gustatory sensibility remains unimpaired, and that in this case the gustatory sensa- 
tions can be localized. It is not, however, absolutely certain that it is the gustatory 
fibers which effect the localization, for the chorda tympani, which was uninjured, 
may carry also a certain number of fibers for general sensation from the facialis root 
in addition to gustatory fibers, as Cushing assumes is the case with the chorda from 
some of his results and from those of Koster. 
M y own observations were made on the young of Ameiurus from 5 to 8 cm. long, 
received from the State fish hatchery, at London, Ohio, in October, 1902, and kept 
under observation in tanks during the following winter. These fishes prove to be 
more shy and less teachable than the smaller Ameiurus fry (about 3 cm. long) hatched 
bv wild parents, upon which the experiments reported in the preceding pages were 
made. 
I have verified on these fishes most of the observations made on the smaller 
fishes last year. The most noticeable difference in their behavior is the evidently 
greater visual power in these fishes. As soon as they began to feed freely in the 
presence of the observer (which required several months of training) they began to 
show evidence of visual recognition of a moving bait, if very near them, and pro- 
sided the}' had just previously been fed with the same food in the same way. They 
never under any circumstances notice visually a still bait, and their recognition of a 
moving bait is at best very imperfect and only an occasional occurrence. 
Upon putting a concealed bait in a tank with the fishes 1 found no evidence that 
they are able to locate it by the sense of smell or otherwise from a distance, provided 
the water is still. If, however, they swim near enough to the capsule containing the 
bait (beef liver, cheese, etc.) to pass the barblets into the strong diffusion currents 
emanating directly from the bait, it is located instantly. The reactions here are 
essentially like those by which the tomcocl localizes a concealed bait, though I have 
not completed the experiment by extirpation of the nose to determine what part, if 
any, is played by the sense of smell. So far as my experiments have gone these 
fishes will not locate a concealed bait in still water unless they pass within 5 cm. of it. 
In running water, however, the case is quite different. I constructed a long, 
narrow tank, so arranged that a slow stream of water can pass through it from end 
