Turner, Homing of Ants. 401 



the workers were much disturbed in the manner stated above. 

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

 was the result of some form of hght stimulus. This was repeated 

 with seven different colonies of Formica fusca. 



To determine whether the intensity or the direction of light was 

 the determining factor, a different kind of experiment was used. 

 The stage and incline were arranged as before. Sometimes the 

 heat-filters were used, but more often they were not. To furnish 

 illumination, four different candle powers (4, 8,16 and 32) of incan- 

 descent electric 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 

 the opposite side of the stage. Shortly it was returned to its for- 

 mer position. A few minutes later a different candle power was 

 substituted for this. This performance was repeated over and 

 over again until each lamp had thus been used one or more times. 

 It was found (Fig. 1 7) that substituting a lamp of one candle power 

 for one of a different power had no disturbing effect on the actions 

 of the ants; but that by any marked change in the angular position 

 of the light, no matter what the candle power, the ants were very 

 much disturbed. This warrants the conclusion that when light is 

 present the direction of its rays plays a prominent role in the home- 

 going of ants whose eyes are normal. 



Lubbock over twenty-five years ago stated this fact, but his 

 observation has been either overlooked or ignored by recent conti- 

 nental writers. 



Experiments with Colored Pathways. — The purpose of the experi- 

 ments now to be described was not to determine whether ants 

 have color vision, but simply to ascertain whether the color of 

 the path plays a pai:t in the home-going of ants. In these experi- 

 ments the usual stage was employed; but the inclines were com- 

 posed of colored papers of practically the same texture. Each 

 incline was composed of one color. Of the color series I used, 

 red, yellow, green, blue, purple; of the brightness series, white 

 and black. When an ant had learned the way down a certain 

 colored incline so well that it was not disturbed by the substitution 

 of another of the same color, an incline of a different color was 



