sSo Papers from the Marine Biological Laboratory at Tortiigas. 



each series the coUinins numbered from i to lo represent the orders. This 

 table shows in percentages for each of the four series of trials made on this 

 day what is shown in table 8 for series I and II combined. If the snap- 

 pers had, in each trial, taken all the white fish before taking any of the 

 blue, then the solid line would run along the icx) per cent level through the 

 first 5 spaces of each series of trials, while the broken line would con- 

 tinue along the same level through the second 5 spaces. Probably if a 

 single snapper could be experimented upon with so large a number of 

 atherinas such a result would be reached. In an experiment involving 100 

 snappers they are crowded together, so that the effort of each to get first 

 at the food stimulates the others. Apparently as a result of this competi- 



tion a snapper frequently takes the nearest atherina, whatever its color, so 

 that blue fish are often taken while white fish are still present. It results 

 that the solid line starts usually somewhere near the 75 per cent level and 

 zigzags downward toward the zero level, while the broken line starts 

 usually near the 25 per cent level and zigzags upward toward the 100 per 

 cent level. 



If the snappers had taken the blue fish as frequently in each order as 

 the white, that is, had not distinguished at all between them, the solid and 

 broken lines would coincide with one another and both would run on the 

 50 per cent level through the entire 10 spaces of each series of trials. If 

 the snappers tended in the successive series of the experiment to take white 

 and blue fish more and more indiscriminately, then in the later series there 

 should be evident an increasing tendency for the broken and solid lines to 



