The Light Relation 



423 



screens is greatest in red, and least in violet; yet the 

 growth in red is not equal to that in white light. The vio- 

 let rays are also important in the production of bloom. 



In the following table there are given, after Teodoresco, 

 the relative areas of leaves developed from the bud in dif- 

 ferent qualities of light during a period of about thirty 

 days. With each plant the leaves occupied equivalent 

 positions on the young shoot : 



EFFECT OF WAVE LENGTH UPON ABEA OF LEAVES, AREAS IN SQ. MM. 



The next table indicates the thickness of the leaf under the 

 different conditions of illumination, and also the number of 

 stomata on equal areas of the lower surface : 



