NEGATIVE PHOTOTAXIS ETC. Of LÜtorillCl 



9 



Fig. 5, B. 



imI i.i diminution observed in the number of individuals is due to two 

 causes : one was that a wet roll of paper was kept at the junction of the 

 glass-plates A and B with the glass-plate C and many reaching there hid 

 themselves in the folds of the roll and could not be observed. Secondly, 

 many slid off the glass-plates at the sides and went to the vertical back- 

 wall c. 



This experiment seemed to answer the first of the two questions given 

 above. It was evident that the reason why the mollsucs scatter tJtem- 

 selves uniformly over rocks is because the rods arc very uneven and 

 rough, and there were nooks and corners in ich ich the animais could, hold 



