1903.] NATURAL SCIENCES OF PHILADELPHIA. 495 



young ants, like the adults, failed to discern any difference in contact-odor 

 due to diversity in the light rays encountered." 



In order to ascertain whether exposure of the inert young to different 

 light-rays would result in different contact-odors at a later time, I 

 took amber pupse, between April 12 and May 12, from the violet nests, 

 and segregated them in a dark Petri cell, and I hke^ise segregated in 

 another dark cell as many pupse from the orange nest. From the 

 violet nests I thus secured about twenty callows, all hatched between 

 April 23 and May 14, that had passed the egg, the larval, and most of 

 of the pupal stage exposed during all dayhght hours to the rays at the 

 upper end of the spectrum and without exposure to the red or green 

 rays. From the orange nest I likewise secured about twenty callows, 

 all hatched between April 17 and May 14, that had been exposed dur- 

 ing the same period to the rays at the lower end of the spectrum, 

 without exposure to blue, violet or ultra-violet rays. No callow had 

 met an ant of other group than the one in which it was hatched. When 

 the youngest callow was one month old, on June 13, 1903, I intro- 

 duced several callows, one by one, from each cell into the other cell. 

 All were amicably received and were straightway permitted to share 

 in the care of the inert young; and when I united all the occupants of 

 the two cells they lived together harmoniously. The exposure of the 

 eggs, the larvce, or the pupce to unlike light-rays does not produce unlike 

 contact-odors in the ants developing from the exposed eggs, larvoe or pupce. 



The results of these experiments shows that the contact-odor of these 

 ants is not affected by the light-rays from which the ant-nurses instinctively 

 withdraw the young; nor is exposure to light a cause of such change in 

 the contact-odor as is coincident with age. 



