All experiments were conducted while the pump at the seaward or 

 western end of the pond was operatingo This projected i strong 

 current of water imo the first 1/ 10T,h of the pond atA a weaker cur- 

 rent into the second l/10*hp the attraction area. In some experi- 

 mentSp the lures only were used; in others^ stock extracts of tuna 

 flesh were introduced through the pump flow at the same time as the 

 lures were presentedo A detailed description of the pond^ pumpp 

 stock extract^ normal behavior of the fish^ etCoj is given in Part I 

 of this report by Tester^ van Weel^ ond Naughtonp and the general 

 arraungement for testing is shown in figure 4o 



In a typical experiment the pump was switched on and the 

 observers on top of the tower waited vintil the fish were behaving in 

 a normal fashionj io e<, „ cruising slowly back and forth along the 

 length of the pond in one or two schools o The activity of the fish was 

 observed and recorded during a 15-minute control period ^the data 

 could be divided into 3-mmute intervalsjo The lures were then dipped 

 momentarily into the water once every I seconds and the activity of 

 the fish was observed and recorded for a 15 -minute experimental 

 periodo The colored lures were then reversed in position (switching 

 left to right and right to left)) and the observations were repeatedo 

 After two or more 15»minute experiments with lureSj stock extract 

 was addedp the lures were dipped into the water „ and observations of 

 activity were made and recorded for another experimental period. 

 The lures would then be switchedj, or changedp dJid the experiment 

 repeated,, In some of the early tests (9/3 and 9/5? the control and/or 

 exppirimental periods were of shorier duration ^9 or 12 mmutesJo 



The behavior of the tunny;, particularly during expert^ 

 mental conditions „ was exceedingly complexo It was difficult to 

 measure the activity with the usual device5==.electrically controlled 

 time clockp stop watch;, and mechanic al counter=--and to record the 

 data with pencil and paper, even when two observers were working 

 together on top of the towero A system of recording the behavior was 

 worked out which consisted eventually of (1) the use of a tape recorder 

 to give a running verbal description of the activity of the fishj and 

 (2) the transcription of this information on the smoked paper of a 

 kymograph drum by operating a series of levers to which styli were 

 attachedo The transcribing apparatus is illustrated in figure 18„ It 

 consists of a kymogrdph iF'^, a Franz kymograph timer 'C- with two 

 recording pointSp a lever 'B) and stylus attached by a cord to the 

 axle of a telephone dial (D; so that the length of the stroke on the 

 drum 18 proportional to the number dialed^ and a lever (A) and stylus 

 attached by a rigid rod to a toggle key (Ei which can be flipped up or 

 down from a neutral position to make an up or down stroke on the 

 smoked paper. The time is recorded by Cp the rumber of fish in 



65 



