Color Discriniination in the Gray Snapper. 



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taken in each order by a colony of lOO gray snappers, at the west lighthouse 

 dock, July 21, 8" to 8" 30'" a. m., when thrown in lots of 10, 5 white and 

 t; blue ; the last 8 of 22 trials ; 80 atherinas thrown ; all taken. 



Table 3. 



The Roman numerals indicate the orders or places for the fish of each 

 color. The Arabic numerals show the number of times that fish of each 

 color were taken in each order; they are the footings for each color of the 

 vertical columns of the original record for the 8 trials included in the table. 



From table 3 it appears that in all of the 8 trials the first and second 

 and fourth fish to be taken were white. In 7 trials the third fish taken was 

 also white ; in i trial blue was third. In every trial of the 8 the seventh, 

 eighth, ninth, and tenth fish taken were bhic. in tlic first 5 orders white fish 

 were taken 34 times out of a possible 40, that is, 85 per cent of the fish taken 

 in the first 5 orders were white, while but 6, or 15 per cent, were blue. In 

 the second 5 orders these numbers were reversed ; 85 per cent of the fish 

 taken are here blue and 15 per cent white. Of the blue fish 32, or 80 per 

 cent, remained untaken until the last white fish was taken. 



The atherinas used in the experiment were of practically uniform size ; 

 they had like taste (sour) ; those of the two colors sank and were inter- 

 mingled at random in each trial. The only constant dift'erence between them 

 was one of color. In taking 85 per cent of white fish in the first 5 orders, 

 while blue fish are still present, and in leaving 80 per cent of the blue fish 

 until all the white had been taken, the snappers show clearly that they dis- 

 criminate between the blue and white fish. It does not follow that they dis- 

 criminate between the colors blue and white. The blue fish are darker than 

 the white ; brightness may therefore be the basis of discrimination rather than 

 color tone. This point can not be determined in experiments involving blue 

 and white only. It is discussed in another place in this paper and reasons 

 are given for regarding the blue-white discrimination as one of color. 



Experiment 27: Blue and red color discrimination. — In this and the fol- 

 lowing experiments of 1907 the atherinas used had been preserved in forma- 

 lin and subsequently soaked in fresh water to remove the formalin. It is be- 

 lieved that enough formalin remained to give to all the atherinas like quali- 

 ties in respect to taste or odor. 



The atherinas used were all females of nearly the same size and were 

 made to float by the following procedure : The viscera were removed through 



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