n] 



HABITS OF CONVOLUTA 



47 



Mysis station themselves on the black part of a 

 dish the bottom of which is half black, half white. 

 The chameleon shrimp, Hippolyte varians, on the 

 contrary, selects the white ground. A similar be- 

 haviour is exhibited by various fishes, trout among 

 others. 



1 i 



Fig. 11. Phototropism of C. paradoxa : the influence of background 

 on phototropic response. The flat, porcelain troughs containing 

 the animals are represented (in plan) by the oblongs. The bottom 

 of each trough is half white and half black. In the diagram, the 

 white ground is indicated by the unshaded, the black ground by 

 the shaded part of the oblong. The animals are represented by 

 dots, and arrows show the direction of the light. a. In bright 

 light. &. In weak light. c. " Choice " of black ground in 

 preference to white ground. 



So striking is the behaviour both of C. roscof- 

 fensis and C. paradoxa with respect to background, 



