26 



PLAXT STUDIES 



Fig. 20. A spray of majtle, showing the ailjustment of the leaves in size and position 

 of Ijlades and length of petioles to secure exposure to light on a horizontiil stem. — 

 AftiT Keener. 



etc., as to give am])le evidence of the effort put fortli by 

 plants to secure a favorable light-relation for their foliage 



Flo ~I r\\o plants bhowinc adjnstmtnt of ]e\%e'* on ^ hori/ontil ^teni Tlie plant 

 to the left is nighlshaile, in whieh small blades are fitted into spaees left by the 

 large ones. The pl.ant to the right is Selaginella, in wliieli small leaves are dis- 

 trihuted along the sides of the stem, and others are displayed along the upper sur- 

 face.— After Kbrneii, 



