THE ORGAN AND SENSE OF TASTE IN FISHES. 
263 
tically the same results as with the hake. After a few tests the fishes ignore sea 
water and plain cotton, but invariably respond to cotton soaked in clam juice and to 
the juice itself as they do to meat. The tomcod reacts to bits of clear gelatin soaked 
up in water essentially as the hake does. 
I also tested the tomcod with hydrochloric acid, 0.2 per cent in distilled water 
and 1 per cent in sea water. Both are obviously avoided. 1 filled a tine pipette 
with a solution of quinine sulphate in sea water, about 0.1 per cent — a very bitter 
solution. The tomcod swims away immediately if applied either to the lips or to the 
pelvic fins, but appears not to notice it if applied to other parts of the body. 
Within two old clam shells, which had been lying in the tank with the tomcods 
for several days and had remained unnoticed, was placed a piece of fresh clam. 
They were then closed together and laid on the bottom of the aquarium containing a 
tomcod. Shortly the fish passed near it, appeared to perceive it, turned from his 
course, and passed and repassed the spot until the shell was located, apparently by 
smell, by a method of “trial and error.” Then he rooted at the shell vigorously 
until the two halves were separated and he could get the meat. I repeated this with a 
piece of squid within the shells with the same result. I tried two empty shells in the 
same way. He saw me put them into the water, came up to investigate, smelled (?) 
of the shells and went away without so much as touching them, and never came back 
to them again. 
These experiments were repeated in many forms many times. In most of these 
cases the efficient organ in discovering the presence of the food was almost certainly 
the pelvic fin. At least, this alone located it, for the fish swam about (possibly 
feebly smelling something good), but did not make a definite movement toward the 
bait until the fins were dragged over the crack between the two shells containing it, 
from which the juices were doubtless being diffused out into the surrounding water. 
Then he backed up in the typical way. If the bait was not found within a very few 
minutes it was left unnoticed, even though subsequently uncovered. 
These fishes almost invariably find a concealed bait, though the hake rarely does 
so. The hake seems to perceive the odor or savor of the food, for he lingers about 
the spot where it is concealed, but never makes a movement to uncover it. The 
tomcod, on the other hand, actively pushes things about with his snout until the bait 
is discovered. But, unlike the gadoid fishes which Bateson describes, these fishes do 
not get the scent of the food at any considerable distance and then search for it. 
They do not notice the bait until within a few centimeters of it, and there is no 
evidence that the sense of smell assists at all in the localization. 
To test this point the olfactory organ was extirpated in several tomcods which 
had given the reaction last described clearly. Several ways of performing this 
operation were tried. The most successful method was to etherize the fish sufficiently 
to keep him quiet and then operate in a shallow tray with the mouth kept under 
water, cutting off the olfactory nerves or crura with a sharp scalpel. The wound 
suppurated badly, but appeared to give the fish no serious trouble, as they feed 
normally from the second day onward. Without going into the details of the observa- 
tions, I may say that after the third or fourth day the fishes took their food in all 
respects like uninjured fishes, so far as could lie observed. They gave all of the 
characteristic reflexes that have been mentioned above, including the discrimination 
