90 CERATOPHYLLUM [CH. vn 



singularities exhibited by Ceratophyllum. In 1877 a French 

 observer, Rodier 1 , recorded the existence of certain spontaneous 

 movements which characterise the shoots of this plant. He 

 noted that the shoot moved in one direction for six hours, and 

 then returned for another six then moved for four hours in the 

 opposite direction, and in another four hours returned again to 

 its original position. Darwin 2 drew attention to certain obscu- 

 rities in Rodier's description, but no more recent work appears 

 to have been done on the subject; the movements of Cerato- 

 phyllum might repay further investigation 3 . 



1 Rodier, E. (iS;; 1 ) and 



2 Darwin, C. and F. (1880). 



3 See also p. 281. 



