CHAP. 

 IV. 



68 



MAIZE 



of cellulose ; as it surrounds each cell, cellulose forms a large 

 part of the substance of the higher plants. Protoplasm is 

 the living substance of the plant, and comprises various 

 minute, differentiated bodies, some of which {the chloroplasts) 

 contain a green colouring matter {chlorophyll), and are present 



Fig. 12. — Flowering plants of maize (Zea Mays). A, Tassel. B, Leaf- 

 blade. C, Leaf-sheath (the stem is entirely surrounded by the sheath). D, Ear 

 surrounded by husks. E, Silk exposed for some days. F, New silk just appear- 

 ing (Photograph by D. W. Macdonald). 



in such enormous quantities that they cause the whole plant- 

 surface to appear green. 



In the more highly-developed forms of plant life the cells 

 are not massed together promiscuously, but are associated in 

 groups forming bands, plates, or cylindrical masses called 



