210 EXPEEIMENTS 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 j% 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 deej) 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 a.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 s(,'em 



