LEAF FUNCTIONS 



105 



to the upper and lower surfaces of a leaf, and will show the same 

 result. 



Thus the end products of all these processes are the carbon 

 dioxide and water, with which the photosynthesis started. The 

 oxygen involved in the destructive processes is the by-product 

 of photosynthesis, so that all three elements, carbon, hydrogen, 

 and oxygen pursue a circular course. 



FIG. 30. 



FIG. 31. 



Figure 30 shows plant with pot sealed, but giving off water vapor which 

 has condensed on bell jar. 



Figure 31. Left-hand figure, shows plant with sealed pot, giving off water 

 vapor enough to turn the cobalt paper pink within fifteen minutes. The right- 

 hand figure is a check experiment, to show that the moisture in the air would 

 not cause the change in the same time. From Atkinson. 



COLLATERAL READING 



Plant Relations, Coulter, pp. 148-161; Botany for Schools, Atkinson, 

 pp. 90-116; Elementary Botany, Atkinson, pp. 53-70; First Studies in 

 Plant Life, Atkinson, pp. 121-125; Lessons in Botany, Atkinson, pp. 

 70-72; Experiments in Plants, Osterhout, pp. 191-202; Biology Text, 

 Hunter, pp. 132-134; Essentials of Biology, Hunter, pp. 115-132; Intro- 

 duction to Biology, Bigelow, pp. 55-75; Plant Life and its Uses, Coulter, 

 pp. 218-234; The Great World's Farm, Gaye, pp. 157-176; The Story of 

 the Plants, Allen, pp. 33-53; Textbook of Botany, Gray, pp. 85-110. 



