1902.] NATURAL SCIENCES OF PHILADELPHIA. 621 



on account of interchanges of the panes. This indicates no prefer- 

 ence for orange, yellow and blue rays. 



Experiment 13. — Time, 45 days. 



Double orange, transmitting red, orange, yellow, green. 



Double green, transmitting yellow, green, blue, indigo. 



The ants moved once to orange on account of interchange in the 

 panes. The green side presented so little of blue and indigo under 

 the spectroscope as to make the presence of those rays doubtful. 

 The ants did not seek the red rays. 



Experiment 14-. — Time, 43 days. 



Double orange, transmitting red, orange, yellow, green. 



Single green, transmitting orange, yellow, green, blue, indigo. 



The ants removed twice from green to double orange. This 

 may indicate preference for red, or avoidance of the blue and 

 indigo. The removals were dilatory, and the ants quickly became 

 indifferent to the rays. 



Experiment 15. — Time, 35 days. 



Double orange, transmitting red, orange, yellow, gi'een. 



Yellow pane, transmitting red, orange, yellow, green, blue, 

 indigo. 



The action of the ants was the same as in the last experiment, 

 and showed that the cause of the removals was not a preference for 

 red, but an avoidance of the blue and indigo. 



Experiment 16. — Time, 50 days. 



Single orange, transmitting red, orange, yellow, green, blue. 



Double green, transmitting yellow, green, blue, indigo. 



The ants remained for consecutive days under each pane, and 

 never removed on account of interchange of the panes. They 

 have not, then, a preference for the red and orange transmitted by 

 the orange pane. 



Experiment 18. — Time, 43 days. 



Single orange pane, transmitting red, orange, yellow, gx'een, blue. 



Single green pane, transmitting orange, yellow, green, blue, 

 indigo. 



The ants stayed consecutive days under each pane. I sometimes 

 interchanged the panes twice a day, but such interchange never 

 caused a change of location of the ant-group. The ants have not, 

 then, a preference for red or for indigo. 



