EXPERIMENTS WITH COLOURED GLASSES. 191 
she yellow, sometimes over the red. I also put four 
thicknesses of violet glass, so that it looked almost 
black. 
Under these circumstances, the pupe were placed 
under the red 7 times, dark yellow 5, once they 
were half under each, but never under the violet, 
purple, light yellow, dark or light green. 
The following day I placed over the same nest, in 
the sun, dark green glass, dark red, and dark yellow. 
In nine observations the pupz were carried three times 
under the red and nine times under the yellow. 
I then tried a similar series of experiments with 
Lasius niger, using a nest in which were about 
40 pup, which were generally collected in a single 
heap all together. As before, the glasses were moved 
in regular order after each experiment ; and I arranged 
them so that the violet followed the red. As far, 
therefore, as position was concerned, this gave violet 
rather the best place. The glasses used were dark 
violet, dark red, dark green, and yellow, the yellow 
being distinctly the most transparent to our eyes. 
Experiment Experiment 
1. Pup under yellow. 8. Pupz under green. 
2. ” ” 9. ” red. 
3. ” ” 10. ” yellow. 
4, 5 a ll. $5 red. 
5. ” ” 12. 3 yellow. 
6. 5 09 13. ” ” 
7. $3 green. 14, a red. 
