OTS THE SENSE OE COLOR AMONG THE LOWER ANIMALS. 205 



On the Seuse of Color among some of tlae Lower Animals. — 

 Part II. By Sir John Lubbock, Bart., Pres. Linn. Soc, 

 P.E.S., M.P., D.C.L., LL.D., &c. 



[Eead April 19, 1883.] 

 In a previous paper which I had the honour of reading before the 

 Society on the l7th November 1881, and which is published in 

 the Journal (xvi. p. 121), I have described some experiments on 

 this subject. 



I placed specimens of our common Daphnia pulex in a narrow 

 shallow trough, threw upon them lights of various colors, and 

 then at stated intervals counted the number of Daphnias under 

 each color. 



A large majority of the Daphnias, though not with tlie same 

 species, in my experiments preferred the part of the trough on 

 which the green light fell ; but on thinking the matter over, it 

 occurred to me that the yellow was perhaps too brilliant. 



M. Merejkowski, who has since experimented on the subject, 

 considers that the Daphnias are attracted wherever there is most 

 light, that they are conscious only of the intensity of the light, 

 and that they have no power of distinguishing colors. It is no 

 doubt true that in ordinary difluped daylight the Daphnias gene- 

 rally congregate wherever there is most liglit. Their eyes are, 

 however, so delicate that one would naturally expect, a priori, 

 that there would be a limit to this ; and, in fact, direct sunshine 

 is somewhat too strong for their comfort. 



Por instance, I took a porcelain trough, T^ inches long, 2| 

 broad, and 1 deep, and put in it some water containing 50 Daph- 

 nias. One half I exposed to direct sunlight and the other I shaded, 

 counting the Daphnias from time to time, and transposing the 

 exposed and shaded halves. The numbers were as follows : — 



In the sun. In the shade. 



At 10.40 A.M 4 46 



12.50 8 42 



1.10 7 43 



1.35 7 43 



1.50 4 46 



2.5 3 47 



2.40 4 46 



3 5 4b 



4 7 43 



4.30 4 46 



53 447 



This seems clearly to show that they avoid the full sunlight. 



