Ihroughout the series there was no definite positxve tropism 

 to radiating white light from a 1+0 -watt (1+7 foot candles) bulb 

 with either continuous or interrupted lighto Although in Experi- 

 ment 1 there were 2 entrances j in Experiments 2,, !;« and 5 there 

 were noneo With continuous light from green^ red^, amber j, and 

 yellow bulbs of intensities ranging from 6 to 62 foot candles , 

 there were no entrances into the field q even though the 100-watt 

 yellow "insect repellent* light had an intensity (62 foot candles) 

 only slightly less than that of the 60=watt white bulb (70 foot 

 candles) which attracted the fish in Experiment 3 of Series iii 

 (table ij,)o 



Lack of response may have been due to the low intensities 

 usedj to a lack of responsive condition in the f ishj, or to a 

 combination of botho Lack of responsive condition is indicated 

 in Experiment 3 using continuouii white light from ' 20D-watt 

 bulb in which only 3 entrances were made as compared with li; 

 in Experiment 3^ Series ii (table 3) o There was no apparent 

 reason for the difference in behavioro As all of the experi- 

 ments were low intensity sources except one (Experiment 1), and 

 also the controls j, produced entrances ^ it is believed that 

 the lack of response was due partly at least to the low intensity 

 of the various white and colored bulbs « 



Series v-— Reactions to the horizontal b e am of a projector and 

 to radiating white an d colored light from bulbs o ~ ~ 



These experiments were performed to study the reaction of 

 txma to a strong (530 foot candles) beam of white lights and 

 to repeat amd extend the observations of Series iv on the 

 reaction to colored light of low intensityo One yellowfin and 

 five tunny were present o The results are shown in table 6o 



The experiments were conducted with the projection lanterno 

 In Experiment 1 there was one entrance by the yellowfin j, but 

 on four occasions the mixed school approached the border of the 

 field and then turned baoko In Eiq^eriment' ? there was no 

 reaction, the fish behaving as under control conditions o That 

 the fish were in a moderately responsive mood Is shown by the 

 6 entrances under stimulation of a 200-watt bulb in Experiment 

 3o It would seem that the tuna were not attracted,, to the field 

 at least, by the strong continuous light bearao 



In experiments h to 6^ light bulbs fitted with rede, greeny 

 and blue filters were used, giving intensities somewhat higher 

 than those of the bulbs of comparable color used in Series iv, 

 but less than those of the ai'c lamp beam of comparable color 

 used in Series lo The green light appeared to attract the tuna^, 

 but it is doubtful if the results are of general significanceo 

 Neither red nor blue light seemed positively attractiveo 



50 



