LEAF FUNCTIONS 



3. Assimilation. 



C, H, O, combined with N, S, P, etc., form proteids, etc. 



4. Respiration. 



Tissue and food plus oxygen = energy plus CO 2 . 



5. Transpiration. 



Giving off large excess of water. 



The Leaf as a Factory 



The factory Green leaves (or other green tissue). 



The work rooms The cells of palisade and spongy layers. 



The machines Chlorophyll grains and protoplasm. 



The power Sunlight. 



Materials Carbon dioxide and soil water. 



Supply department Root hairs, ducts, air spaces, stomates. 



Transportation dept. Ducts, bast tubes, pith rays. 



Finished products Starch, sugar, proteids, tissues. 



Waste product Oxygen. 



. I Manufacturing dept. daylight only. 



Hours of work 



{ Transport and supply depts. day and night. 



Comparison of Photosynthesis and Respiration 



Photosynthesis Respiration 



Constructive process Destructive process 



Food and tissue accumulated Food frnd tissue used up 



Energy taken in from sun Energy released 



Carbon dioxide taken in Carbon dioxide given off 



Oxygen given off Oxygen taken in 



Complex compounds formed Simple compounds formed 



Produces starch, etc. Produces CO 2 and H 2 O 



Goes on only by day Goes on day or night 



Only in presence of chlorophyll In all parts exposed to air 



EXPERIMENTS WITH LEAVES 



To show that Leaves (and Stems) turn toward Light. Two 

 thrifty plants are provided, one is placed in a light-tight box, 



