A PRELIMINARY NOTE ON ANT BEHAVIOR. 35 



as for ants working in concert ; but, marked ants were used and 

 only one was allowed to work at a time. In all essential points, 

 the results harmonized with those obtained from ants acting in 

 concert. In most cases, however, after a greater or lesser lapse 

 of time, the ant would usually find its way down the old incline 

 to the nest ; and, after a greater lapse of time, find its way back 

 again to the stage. 



That the above effect was not due to heat was proven in the 

 following manner. At the right and left of the stage used was 

 placed a tall museum jaw .34 cm. x 16 cm. x I/ cm., filled with 

 distilled water. These heat filters were so adjusted as to have 

 their broad sides parallel to the edges of the stage. At the be- 

 ginning of the experiment, a 32 c. p. incandescent lamp was 

 placed behind one of these filters (usually behind the one that 

 was near the incline). After the ants had traveled the path long 

 enough to make the trips regularly and rapidly, the lamp was 

 transferred to behind the opposite filter. In every case the 

 workers were much disturbed in the manner stated above. This 

 was repeated with seven different colonies of Formica fusca. Since 

 the heat had been excluded, it is evident that the disturbance 

 was the result of some form of light stimulus. 



To determine whether the intensity or the direction of light 

 was the determining factor, the experiment was slightly modi- 

 fied. The stage and incline were arranged as before. Some- 

 times the heat filters were used, but more often they were not. 

 To furnish illumination, four different candle powers (4 c. p., 8 

 c. p., 16 c. p., 32 c. p.) of incandescent lamps were used, one at a 

 time, in a darkened room. At the beginning of the experiment 

 a lamp of a certain candle-power was placed near the side of the 

 stage to which the incline was attached. After the ants had 

 thoroughly learned the way home a different candle-power was 

 substituted for the first. After the lapse of a few more minutes 

 this lamp was transferred to near the opposite side of the stage. 

 Shortly it was returned to its former position. A few minutes 

 later a different candle-power was substituted for this. This 

 performance was repeated over and over again until each candle- 

 power had been used one or more times. 



It was found that substituting a lamp of one candle-power for 



