4 



K. MITSTJKUBI. 



of negative phototaxis shown hy these molluscs must necessarily lead 

 them to move landward instead of sea-ward in their native habitat, and 

 must lead them to act as if they had a notion as to which way lay the 

 land and which way the water. Accordingly I walked along the shore- 

 line, carefully observing how light struck my eyes. There could be no 

 question as to which gave out more light : wherever 1 might put myself 

 along the shore, (except on detached rocks) there was always more light 

 facing the sea than when facing landward. In order to test this point 

 further, I tried the following 



Experiment 5 (Aug. 7) : — An oblong flat glass-dish was made by 

 erecting narrow strips of glass along the 

 edges of a window pane about 35 x 30 cm. 

 and by holding them there by putting a 

 mass of putty outside them. This I took to 

 Naközaki, a place near the Station. The 

 dish was placed on the rocky and sandy 

 beach with its longer axis as a normal to 

 the beach-line and as nearly horizontally as 

 possible (Fig. 3). The glass-dish was made 

 just a little wet by having a thin layer of 

 sea- water. 100 individuals were picked off 

 at random from the rocks near about and 

 Fig. 3. placed in the center of the dish. The time 



was 2 :48 P. M. (Aug. 7) and the midsummer sun was pouring down 

 its rays from overhead equally all over the plate. At 4 :30 P.M. the 

 individuals were distributed as follows : — 



The quarter with the corner 



a 



6 ! 



24 



The quarter with the corner 



b 



18 ) 



The quarter with the corner 



c 



39 i 



66 

 90 



The quarter with the corner 



cl 



27 J 



90 = 



Missing 





10= 



10 



Total 





100 = 



ÎÔÔ" 



