538 G.H.Parker 



immersed in water and the nasal apertures were tested with a 

 mixture of water and carmine. By this means it was easy to 

 demonstrate that a current of water entered the anterior nasal 

 aperture and emerge from the posterior one, as has alread) been 

 shown in Amia b}/ Brookover ('lo, p. 77), and that the water 

 passed through the olfactory chamber of the catfish in from eight 

 to ten seconds. It is therefore certain that even in the resting 

 fish a continuous current of water is coursing through the nasal 

 chamibers from anterior to posterior, and, judging from the posi- 

 tion of the nasal apertures on the body of the fish, this current is 

 probably accentuated by forward locomotion. 



If the nasal chambers of a resting fish are continuously provided 

 with a flow of water from the exterior by which odorous material 

 may be carried to the olfactory surfaces, the failure of the animal 

 to respond to such material must have some deeper seat than the 

 receptive organ. Since what appeared in the normal catfish to 

 be a scenting reaction was observed only when the animal was in 

 locomotion, it seemed to me that this condition might be the only 

 one under which olfactory responses would be exhibited, and that 

 the resting fish represented a state wholly unfavorable for such 

 reactions. In other words, it seemed possible that only when the 

 central nervous organs were discharging impulses to locomotion 

 were they in a condition to transmit impulses eminating from the 

 olfactory receptors. With this idea in mind, I set about devising 

 a new line of experimentation to be carried out on the actively 

 swimming fish. 



As a preliminary to a revised method of procedure, five normal 

 fishes were placed in a large aquarium over night that they might 

 become accustomed to their surroundings. In this aquarium 

 were then hung two wads of cheese-cloth, in one of which was con- 

 cealed some minced earthworm. The fishes, which were swim- 

 ming about near these wads, w^ere then watched for an hour and 

 their reactions in reference to the wads were recorded. The 

 wad without worms was passed by the fishes many times and did 

 not excite any noticeable reaction. The wad containing the 

 worms was seized and tugged at eleven times in the course of 

 the hour notwithstanding: the fact that from time to time this 



