the movements of the fish and assured com- 

 parable distribution at the start of each test. 

 It was placed in the center of compartment 

 A, and raised 10 seconds before the begin- 

 ning of test conditions . The infrared source 

 was attached to the wall of the tank nearest 

 the observer. It was located within compart- 

 ment A, close to the outside wall so that any 

 "escape" from the radiation must be in the 

 direction of compartment B. A heavy black 

 curtain shielded compartment B from the 

 radiation in compartment A, although there 

 was some light leakage under the gate. The 

 beam was directed so that it met the surface 

 of the water across the tank, and an addi- 

 tional reflecting surface --a board painted 

 white- -was provided at that point. The same 

 source, with filter removed, was employed 

 in the "light" part of the experiment. 



Fingerling silver salmon ( One orhynchu s 

 kisutch) of a size range from 7 to 1 1 cm . 

 (total length) were used in the experiment . 

 They were unconditioned fish which had not 

 previously been exposed to the electrical 

 fields of the guiding experiments . 



Attraction 



The fish might not seek to avoid the 

 infrared radiation and react as in dark- 

 ness, and still be influenced by the radia- 

 tion. It may serve to attract them . For 

 that reason, and to detect possible influ- 

 ences peculiar to one or the other compart- 

 ment, the restraining cage was transferred 

 to compartment B and the experiments 

 repeated. The li^it source remained in 

 compartment A, in its original position. 



The results of six trials of each con- 

 dition are shown in table 1 . 



It is evident from table 1 that the fish 

 did not react differently to infrared radia- 

 tion and to darkness. They remained 

 unmoved under the infrared in one compart- 

 ment, and they did not seek it from the 

 other compartment; they were neither 

 repelled or attracted by the infrared radia- 

 tions . 



Orientation 



Reactions of the fish were observed under 

 three conditions: (1) infrared radiation, 

 (2) visible light, and (3) darkness. A random 

 sequence of conditions was not required, 

 since separate lots of 50 fish each were used 

 in each trial. With the gate between com- 

 partments raised, and tlie overhead light 

 burning, the fish were placed in the wire 

 cage. The li^-t was extinguished, and the 

 tank was kept in darkness for 5 minutes. At 

 the end of that tim.e the cage was raised and 

 the fish were released. Ten seconds were al- 

 lowed to elapse, and the test phase was begun. 

 At the end of 15 seconds of experimental con- 

 ditions the gate was released, falling sharply. 

 The overhead light was then turned on, and 

 the fish in each compartment v;ere counted. 



The schooling proclivity of young 

 salmon, and other fishes, is commonly 

 laid to a visual orientation facility. Such 

 a reaction is difficult to measure, but may 

 be readily observed and recorded. To that 

 end a small tanic, 3 by 3 feet, was placed 

 in the photographic darkroom of the labora- 

 tory, the infrared source and a camera 

 focused on the tanic, and the infrared tele- 

 scope placed handy for observation . The 

 water depth was 4 inches . The school of 

 young silvers shown in figure 4 formed 

 under the overhead light of the room and 

 was photographed on black and white film . 

 With infrared the only radiation in the room, 

 the school was observed through the tele- 

 scope. Dispersal was complete in a matter 



