154 



The Living Plant 



Fig. 49. — ^Generalized drawings of optical sections through the principal forms of plant 

 cells, all of which are derivable by differential growth from the spherical form in the 

 center. 



approach to this shape in the green cells of leaves, (figure 2), al- 

 though here a modification is introduced by the need for con- 

 centrating the chlorophyll grains towards the best-lighted sur- 

 face, for which a cylindrical shape is the best (Plate I, B), or else 



