194 DISLIKE OF VIOLET. 



1 should rather say, inversely as they would, on a 

 photographic plate. It might even be alleged that the 

 avoidance of the violet glass by the ants was due to their 

 preferring rays transmitted by the other glasses. From 

 the habits of these insects such an explanation would be 

 very improbable. If, however, the preference for the 

 other coloured glasses to the violet was due to the trans- 

 mission and not to the absorption of rays — that is to 

 say, if the ants went under the green rather than the 

 violet because the green transmitted rays which were 

 agreeable to the ants, and which the violet glass, on 

 the contrary, stopped — then, if the violet was placed 

 over the other colours, they would become as distasteful 

 to the ants as the violet itself. On the contrary, how- 

 ever, whether the violet glass was placed over the others 

 or not, the ants equally readily took shelter under them. 

 Obviously, therefore, the ants avoid the violet glass 

 because they dislike the rays which it transmits. 



But though the ants so markedly avoided the violet 

 glass, still, as might be expected, the violet glass cer- 

 tainly had some effect, because if it were put over the 

 nest alone, the ants preferred being under it to being 

 under the plain glass only. 



I then compared the violet glass with a solution 

 of ammonio-sulphate of copper, which is very similar in 

 colour, though perhaps a little more violet, and arranged 

 the depth of the fluid so as to make it as nearly as pos- 

 sible of the same depth of colour as the glass. 



