Power to Adjust Parts to Surroundings 



225 



knows; but when the same plant is grown in the window of a room, 

 where the hght is wholly one-sided, it turns all its parts in that 

 direction, even to the extent of seeming to reach out, as it were, 

 after the light (figure 74). The same thing occurs commonly in 

 nature, as may be noticed along the margin of shrubbery or close 



Fig. 74. — Two "Geraniums" which for two or three days before their pictures were taken, 

 were kept, respectively, in a uniformly lighted greenhouse and a chamber lighted only 

 from the right hand side. 



to high buildings or banks; and it can be demonstrated ver}^ 

 prettily by experiment (figure 75). 



A close observation of these cases shows always that stems and 

 leaves behave very differently in relation to the direction of the 

 light, for while stems point straight towards it, leaves set their 

 faces across it. This suggests the inquiry, — what, then of roots? 



