EXPERIMENTS WITH COLOURED SOLUTIONS. 195 
Approx. number 
of Ani Exp.1. Exp. 2. Exp. 3. Exp.4. Exp. 5. Exp. 6. 
under the 
Glass ... 0 0 0 2 0 2 
Solution... 40 80 100 80 50 70 
Exp. 7. Fxp. 8 Exp. 9. Exp. 10. Total 
Glass ... 0 2 3 0 ais 9 
Solution... 60 40 90 100 nee 710 
In another experiment with Lasius niger I used 
the dark yellow glass, dark violet glass, and a violet 
solution of 5 per cent. ammonio-sulphate of copper, 
diluted so as to be, to my eye, of exactly the same tint 
as the violet glass; in 8 observations the pupa were 
three times under the violet solution, and 5 times 
under the yellow glass. I then removed the yellow 
glass, and in 10 more observations the pupe were 
always brought under the solution. 
It is interesting that the glass and the solution 
should affect the ants so differently, because to my 
eye the two were almost identical in colour. The 
glass, however, was more transparent than the solu- 
tion. 
To see whether there would be the same difference 
‘ between red glass and red solution as between violet 
glass and violet solution, I then (Aug. 21) put over a 
nest of Formica fusca a red glass and a solution of 
carmine, as nearly as I could make it of the same tint. 
In 10 experiments, however, the ants were, generally 
speaking, some under the solution and some under 
the glass, in, moreover, as nearly as possible equal 
numbers. 
August 20.—Over a nest of Formica fusca con- 
