344 
PHYSIOLOGY. 
BOOK II. 
by the removal of the petiole. Leaves immersed in water 
under similar circumstances, with their petioles and stem un- 
injured, turned towards the light as they would have done in 
the open air. 
Those who desire more information upon this very curious 
subject should consult Dutrochet's work, Stcr la Motilite des 
Vegetaux, 
