210 EXPERIMENTS WITH 
Although the bisulphide of carbon is so perfectly 
transparent, I then thought I would try it without 
the violet glass. I therefore covered part of the nest 
with violet glass, a part with a layer of bisulphide of 
carbon, moving them from time to time as before, and 
the ants in every case went under the bisulphide. 
I then reduced the thickness of the layer of bisul- 
phide to 54; of an inch, but still they preferred the 
bisulphide. 
Then thinking that possibly the one shelter being a 
plate of glass and the other a liquid might make a 
difference, I tried two similar bottles, one contain- 
ing water and the other bisulphide of carbon; but in 
every case the ants went under the bisulphide of 
carbon. On the other hand, when I used coloured solu- 
tions so deep in tint that the ants were only just visible 
through them, the ants went under the coloured liquids. 
October 10.--I uncovered the nest at 7 4.M., giving 
the ants an option between the bisulphide of carbon 
and various coloured solutions, taking for violet am- 
monio-sulphate of copper ; for red, a solution of carmine 
so deep in tint that the ants could only just be seen 
through it ; for green, a solution of chlorate of copper; 
and for yellow, saffron. They were each separately 
tried with the bisulphide, and in every case the ants 
preferred the coloured solution. . 
I now took successively red, yellow, and green 
glass ; but in every case the ants preferred the glass to 
the bisulphide. Although, therefore, it would seem 
