188 



Sir John Liibhock 



[May 9, 



the food. I then placed the food on top of a rod of wood 8 inches 

 high, in fact a pencil, and when the ant knew her way perfectly well 

 to the food, so that she went quite straight backwards and forwards 

 to the nest, I found that if I moved the pillar of wood only 6 inches, 

 the ant was quite bewildered, and wandered about backwards and 

 forwards, round and round, and at last only found the pillar accident- 

 ally as it were. 



Under these circumstances, I could not apply to ants those tests 

 which had been used in the case of bees. At length, however, it 

 occurred to me that I might utilize the dislike which ants, when in 

 their nests, have to light. Of course, they have no such feeling when 

 they are out in search of food : but if light be let in upon their 

 nests, they at once hurry about in search of the darkest corners, and 

 there they all congregate. If, for instance, I uncovered one of my 

 nests, and then placed an opaque substance over one portion, the ants 

 invariably collected in the shaded part. 



I procured, therefore, four strips of glass, similar, but coloured 

 respectively green, yellow, red, and blue, or, rather, violet. The 

 yellow was somewhat paler in shade, and that glass cousequently 

 more transparent than the green, which, again, was rather more trans- 

 parent than the red or violet. I then laid the strips of glass on one 

 of my nests of Formica fusca, containing about 170 ants. These ants, 

 as I knew by previous observations, seek darkness, and would cer- 

 tainly collect under any opaque substance. I then, after counting the 

 ants under each strip, moved the colom'S gradually at intervals of 

 about half an hour, so that each should by turns cover the same portion 

 of the nest. The results were as follows — the numbers indicating 

 the approximate numbers of ants under each glass (there were some- 

 times a few not under any of the strips of glass) ; — 



3. 



4. 



5. 



7. 



8. 



