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; *, xylem. The last three elements compose the 
fibre-vascular bundle, the cambium being continuous from bundle to 
bundle; the portion between the bundles is called interfascicular cambium. 
