210 



SIR JOHN LUBBOCK ON THE SENSE OF COLOR 



trougli (2) half of wMeli was covered with yellow (aurine). 

 On one side was a similar trough (3), one end of which was 

 shaded by a porcelain plate ; and on the other side a fourth 

 trough (4), one end of which had a little, though but little, 

 extra light thrown on it by means of a mirror. As before, I 

 counted the Daphnias from time to time, and turned the troughs 

 round. All four were in a light room, but not actually in direct 

 sunshine. Thus, then, in one trough I had half the water in 

 somewhat green light ; in the second trough, half the water in 

 yellow light ; in the third, one half was exposed and the other 

 somewhat darkened ; while the fourth, on the contrary, gave me 

 a contrast with somewhat more vivid light. If, then, the Daphnias 



