THE PLANT BODY 



87 



the manufacture of proteins and the living material itself by 



the addition of nitrogen and various other chemical elements. 



In every case all types of food built up in the leaves must 



be distributed to the organism as a whole. This occurs 



Transpiration Respiration Photosynthesis 



Foods 



Cortex 



\Phloem (food path) 

 \XyUm (water path) 

 Pith 



Absorption 

 Water 



Salts-'"^''' 

 Oxygen' 



\Respiratfon 



FIG. 48. Diagrammatic presentation of the chief physiological activities of a Flower- 

 ing Plant (Bean). The first leaves (seed leaves, or cotyledons) are richly stored with 

 food but contribute only slightly to photosynthesis. (From Densmore.) 



chiefly by diffusion in the form of soluble carbohydrates (e.g., 

 grape sugar) or in soluble nitrogenous form (e.g., amines or 

 soluble proteins) to the smallest veinlets and then on to 

 larger and larger veins, which finally deliver it to the stem. 



