NEGATIVE PHOTOTAXIS ETC. OF Littovina. 



15 



Sept. 1, 8 : 30 A. m. Another bigli and low tide daring the 

 interval. Individuals scattered but still more or less near 

 the original area. One about two feet from it. 



I will conclude with another experiment : — 



There is a large rock lying near the landing place of our laboratory. 

 When the tide was at the level of the dotted line (See Fig. 6.), I placed some 

 individuals of L. exigua which were known to be negatively phototaxic 

 at the spot A of this rock a little below the water line. The spot was 

 about ten feet from the high bank near the landing place. The question 

 was whether these individuals would go in the direction of the high bank 

 or toward the higher part of the same rock which was turned away from 

 the general mass of land. There was no ambiguity about the answer. 

 As soon as they were placed there, they starte! in the direction of the 

 arrow toward the higher part of the rock A. 



I now took some of these negative ones to a spot on a ledge of rock 



Fig. 6. 



