RHEOTROPIC RESPONSES OF EPINEPHELUS STRIATUS 



439 



While engaged in a study of the reactions of this fish, in connection 

 with certain work on its central nervous system, I made use of an ap- 

 paratus of the following nature: In a large spawning trough (fig. I, A), 

 such as is used in fish hatcheries, I suspended by two supports (B, B) 

 a cage (D), about 36 inches long by 18 inches wide and 10 or 12 inches 

 deep, made of galvanized "chicken wire." A current of fresh sea 

 water was introduced at one end of the cage, at an angle of about 30 

 with the horizon, by a 1-inch hose pipe, for the purpose of affording a 



B 



D 



i 



4. 



D 



li 



Fig. 1. Diagram of cage as seen from above. A, Large spawning trough; 

 B, rods supporting cage; C, current of spawning trough; C", additional currents 

 from hose pipe; D, wire cage suspended from B. 



better supply of water than was furnished by the sluggish current of 

 the trough, flowing in the same direction. 



When several normal fishes had been put in the cage for temporary 

 storage, it was noticed that their orientation was no longer promis- 

 cuous, as in quiet water, but that an unusual position was assumed 

 by nearly all of them (fig. 1). The cause of this was not at once appar- 

 ent; but a little experimentation showed that the new orientation was 

 in response to the stimulus of the seawater delivered through the hose 

 pipe. Contraiy to the usual rheotropic response of fishes, they had 



