206 ANTS NOT SENSITIVE TO ULTRA-RED RAYS, 
from the edge of the red to a distance beyond the violel 
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 pupe 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 pups 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 ail 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 pupe 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 
