EXPERIMENTS WITH COLOURED GLASSES. 193 
red and green, on the contrary, very transparent, and 
the yellow even more so. The yellow was not darker 
than a tincture of saffron. The latter indeed, to my 
* eye, scarcely seemed to render the insects under them 
at all less apparent ; while under the violet and purple 
I could not trace them at all. I altered the relative 
positions as before, The nest contained about 50 
larvee and pupe. 
I made thirteen trials, and in every case the larve 
and pupz were brought under the yellow or the green 
—never once under any of the other colours. 
Again, over a nest of Formica fusca containing 
about 20 pupz I placed violet glass, purple glass, a 
weak solution of fuchsine (carmine), the same of 
chloride of copper (green), and of bichromate of potash 
(yellow, not darker than saffron). 
I made eleven trials, and again, in every case the 
pups were brought under the yellow or the green. 
I then tried a nest of Lasiws flavus with the 
purple glass, violet glass, very weak bichromate of 
potash, and chloride of copper as before. 
With this species, again, the results were the same 
as in the previous casés. 
In all these experiments, therefore, the violet and 
purple light affected the ants much more strongly than 
the yellow and green. 
It is curious that the coloured glasses appear to 
uct on the ants (speaking roughly) as they would, or, 
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