THE ORGAN AND SENSE OF TASTE IN FISHES. 
271 
to end. By covering - the lower end of the tank and illuminating moderately the 
upper end, it can be so arranged that the negative phototaxis will counteract any 
positive rheotaxis and the tishes will remain in the lower end of the tank. If now 
liver or other strong bait is placed above them, the fishes will promptly swim up 
the current and locate the meat. 
The experiments seem to indicate that concealed food can not be located by these 
fishes from a distance in quiet water (cf. Nagel, 181*1), but that if the fish passes 
within a few centimeters of it the diffused juices are recognized and the food located 
promptly. In running water, however, the fishes will follow the diffused juices up 
the stream for considerable distances and so find the food — a fact well known to 
every fisherman. Tactile sensations are clearly not involved; it lies between the 
senses of smell and taste, and I have not as yet gone far enough with this series of 
experiments to decide finally the part played by the sense of smell. 
I have, however, tested the sensitiveness of the barblets to diffused savors 
more fully. Raw meat or beef liver was minced, extracted in a little water, and 
strained. A wisp of cotton was wound on the end of a slender wire, dipped in the 
meat juice, and gently lowered so as to lie a few millimeters from the tip of a barblet 
of a cat-fish which was otherwise entirely concealed under a large leaf. The fish was 
unable to see the cotton and actual contact with the barblet was carefully avoided. 
Within a few seconds the fish became conscious of the savor and turned toward the 
cotton. Again, I filled a glass tube, of about 3-mm. bore, with the meat juice, closed 
the upper end with the finger, and carefully lowered the open end down over a pro- 
jecting barblet, as in the previous case. The specific gravity of the meat juice is 
slightly greater than that of the water, and from the lower end of the tube (the upper 
end being kept closed) the juice slowly diffused downward enveloping the tip of the 
barblet, without, however, any noticeable current being produced in the water. The 
fish locates the stimulus and turns toward the source of it. In other cases I colored 
the juice with a little blood, so that the course of the diffusion currents could be 
observed, and it is evident that the reaction follows the stimulus of the barblet only, 
and not the organ of smell, for the movement is made before the diffusion currents 
have had time to reach the nostril. ' 
These reactions are not as prompt or precise as those given after a contact with 
a sapid substance where a tactile sensation accompanies the gustatory, and in a large 
percentage of the cases there is no definite reaction toward the point stimulated, but 
merely the more vague “seeking reaction” to which reference has been made above. 
Nevertheless they indicate on the whole that pure gustatory stimuli, if very strong 
and applied to a small area of the percipient organ, cam be localized in space, or have a 
“ local sign." 
May 30, 1003. 
