66 



THE VEGETATIVE FUNCTIONS OF PLANTS 



FIG. 50. Photomicrograph of a portion of the system of veins in a 

 leaf of the rubber-plant (Ficus elastica). Enlarged about six times from 

 a portion of Fig. 49. 



FIG. 51. The castor-oil plant (Ricinus communis). Portion of cross- 

 section of young stem, co, Cortex; p, pith or medulla; e, epidermis; ph, 

 phloem; ca, cambium; x, xylem. The last three elements compose the 

 nbro-vascular bundle, the cambium being continuous from bundle to 

 bundle; the portion between the bundles is called interfascicular cambium. 



