192 EXPERIMENTS WITH COLOURED GLASSES. 
Experiment Experiment 
15. Pupe under green. 24. Pup under red. 
16. $5 +g 25. os yellow, 
17. 55 yellow. 26. 35 red. 
18. ” ” 27. ” ” 
19. 3 red. 28. $5 3 
20. ” ) 29. ” ” 
21. » yellow. | 30. - yellow. 
22. ” ” 31. ” red. 
23. ” 7) 32. es green. 
I now put two extra thicknesses of giass over the 
red and green. 
33. Pupz under red. 37. Pupe under red. 
34. 3 yellow. 38. 33 35 
35. 5 red. 39. ss yellow. 
36. 53 yellow. | 40. 9 red. 
The result is very striking, and in accordance with 
the observations on Formica fusca. In 40 experi- 
ments the pups were carried under the yellow 19 
times, under the red 16 times, and under the green 5 
times only, while the violet was quite neglected. 
After the first twenty observations, however, I removed 
it. 
I then tried a nest of Cremastogaster scutellaris 
with violet glass, purple glass, and red, yellow, and 
green solutions, formed respectively with fuchsine, 
bichromate of potash, and chloride of copper. The 
purple looked almost black, the violet very dark; the 
