of the Seta of Funaria hygrometrica. 



36J 



ing round, I think it is probable that during this period a 

 further twisting of the whole seta takes place, this direction 

 being given by the already spiral form of the fibres, and con- 

 stituting the true cause of the motions observed. This is 

 rendered more probable by the fact that the spiral form of the 

 tissue exists even after it has been macerated in water. 



Fig. 1. 



Fig. 2. 



Fig. 3. 



The subject of the spiral direction so frequently observed in 

 the tissue of plants is one of gi*eat interest, and I believe little 



2 D 2 



