206 ANTS NOT SENSITIVE TO ULTRA-KED EAYS, 



from the edge of the red to a distance beyond the violet 

 as great as the whole length of the spectrum. I began 

 at 4.15. By degrees they were all cleared away from the 

 spectrum, except those in the violet, where indeed, and 

 immediately outside of which, the others were placed. 

 At 5, however, they began to carry them back into the 

 red. At 5.45 the blue and violet were nearly cleared, 

 the pupae being placed in the red and yellow. At 6.15 

 they had all been brought from the violet and ultra- 

 violet into the red and yellow. 



I then shook up the pupae so that they were 

 arranged all along one side of the nest, and extended 

 about an inch beyond the red. This excited the ants 

 very much, and in less than ten minutes all those in the 

 spectrum, and for about 6 inches beyond the violet, were 

 moved, but at first they were put down anywhere, so that 

 they were scattered all over the nest. This, however, 

 lasted for a very short time, and they were all carried 

 into the dark beyond the red, or into the extreme end 

 at some distance beyond the violet. At 7 the edge 

 of the heap of pupae followed the line of the red at one 

 end, coming about ^ inch within it, which was not 

 owing to want of room, as one side of the nest was 

 almost unoccupied; at the other end they were all 

 carried 3 inches beyond the end of the violet. 



It would seem, then, as the result of these experi- 

 ments, that the limits of vision of ants at the red 

 end of the spectrum are approximately the same 

 as ours, that they are not sensitive to the ultra-red 



