NEGATIVE PHOTOTAXIS ETC. OF Littorina. 



13 



An eighth, going down, removed on tbe flat dish, negative. 



A ninth, (L. sitchana, var. brevicula), going down, removed on the 

 flat dish, at first turned about as if it could not make up its mind, and 

 then became negative. 



The results of these experiments were confirmed by another. 



Aug. 30, 8 A. M. Went to Nakozaki. A group of Littorina- 

 lying attached to a nearly vertical face of rock, just above 

 the water level was chosen, and water was splashed on with 

 hands for about five minutes. On splashing being stopped, 

 many began downward movements and reached water's 

 edge in about half an hour. One went upwards. 



Two other lots of these shells (A) and (B) near highwater mark 

 were selected. First, some individuals from the both 

 groups were tested in water and found to be negatively 

 phototaxic. After this, water was splashed on them, on 

 one (A) 50 bucketfuls. In one group (A), no movements 

 followed. The shells could not be roused, so to speak, from 

 their quiescence. In the other group, (B), two were dis- 

 tinctly seen to go downwards, while four went upwards. 

 Drying of rooks, however, stopped the motions of all the 

 individuals quickly. First splashing made a few roll down. 



It seemed now tolerably certain to me that the molluscs in being 

 driven upward by the advancing tide must necessarily be subjected for 

 hours to the splashing of little waves, and therefore when the receding 

 tide leaves them comparatively quiet, they must become positively 

 phototaxic and move down toward the sea. 1 therefore went to Naközaki 

 and made the following observations. 



Station XII. Aug. 30, 8: 30 A. M. Tide receding. An area 

 circumscribed on a vertical face of rock around 20 indivi- 

 duals which were also marked. 



