ANTS NOT SENSITIVE TO ULTRA-RED RAYS. 206 



mcnng the nest was to bring some of them into the 

 violet, though most were in the ultra-violet. They 

 were, as before, all carried into the dark space beyond 

 the red in about half an hour. 



"We then turned the glass round again, this time 

 arranging the end about the length of the spectrum 

 beyond the end of the violet visible to our eyes. They 

 began clearing the thalline band, carrying some into 

 the violet, but the majority away further from the 

 spectrum. In a quarter of an hour the thalline band 

 had been quite cleared ; and in half an hour a band 

 beyond, and equal to the thalline band, those in the 

 violet being left untouched. After the pupae in the 

 ultra-violet portion had all been moved, those in the 

 violet were also carried away and deposited about twice 

 as far from the edge of the violet as the further edge 

 of the bright thalline band. 



Experiment 10. — Experimented again with the 

 same arrangement as before, using another nest of 

 Lasius niger and placing the pupae in the violet and a 

 little beyond. The ants at once began removing them 

 into the dark, tunnelling into the heap, and then carry- 

 ing away those in the ultra-violet first, although they 

 were further off. In half an hour they had all been 

 moved out of the violet and ultra-violet, about half 

 being placed in the dark, and half having been pro- 

 visionally deposited in the red and yellow. 



ExpeHment 11. — Same arrangement as before. 

 The pupae being placed all along one side of the nest, 



