196 EXPERIMENTS WITH COLOURED SOLUTIONS. 
taining 20 pupe, I placed a saturated solution of 
bichromate of potash, a deep solution of carmine, which 
let through scarcely any but the red rays, and a white 
porcelain plate. 
re Under the bichr. of potash were 0 pupzx, carmine 18, porcelain 2 
2 ” ” 0 ” ” 6 ” 14 
3 ” ” 6 ” ” 3 » il 
4. ” 0 ” ” 5 ” 18 
5. ” ” 6 » ” 4 a ] 0 
6 ” ” 9 ” ” 19 ” 1 
7 ” ” Oo» ” Oo , 20 
8 ” ” 4 ” ” 15 ” 1 
9. ” ” 2 ” ” 4 ” 14 
10. ” ” 0 ” ” 4 ” 16 
iW ” ” 0 ” 0 3 ” 17 
Total 18 81 124 
I then put over another nest of Formica fusca 
four layers of red glass (which, when examined with 
the spectroscope, let through red light only), four 
layers of green glass (which, examined in the same 
way, transmitted nothing but a very little green), anda 
porcelain plate. Under these circumstances the ants 
showed no marked preference, but appeared to feel 
equally protected, whether they were under the red 
glass, the green glass, or the porcelain. 
Thus, though it appears from other experiments 
that ants are affected by red light, still the quantity 
that: passes through dark red glass does not seem greatly 
to disturb them. I tested this again by placing over a 
nest: containing a queen and about 10 pupz a piece of 
