66 



PHOTOSYNTHESIS 



he found that the absorption of carbon dioxide by the two leaf surfaces 

 also followed the stomatic ratio. 



With some improvements in methods, Brown and Escombe '' repeated 

 the work of Blackman and determined the amounts of carbon dioxide 

 emitted and absorbed by the two sides of various leaves on which the 

 distribution of the stomata was ascertained by actual counting under the 

 microscope. The results obtained for carbon dioxide evolution are given 



in Table 9. 



TABLE 9 



Emission of Carbon Dioxide from Upper and Lower Surface of Leatcs during 

 Respiration. (From Brown and Escombe.) 



Stomatic Ratio. CO2 Emitted. 



Upper Surface Upper Surface 



Lower Surface Lower Surface 



Time in 

 Plant Hours 



Canna indica 4.75 



•' 5.00 



4.23 



Runicx alpinuin 5.50 



Leaf Area 

 in Sq. Cm. 



28.27 

 28.27 

 28.27 

 59.44 



100 

 246 

 100 

 246 



100 

 246 



100 

 269 



100 

 246 

 100 

 322 



100 

 210 

 100 

 286 



Similarly the results obtained for the absorption of COo during photo- 

 synthesis are given in Table 10. 



TABLE 10 



Absorption of Carbon Dioxide on Upper and Lower Surface of Leaves during 

 Photosynthesis. (From Brown and Escombe.) 



Stomatic Ratio. CO2 Fixed. 



From these experiments it can ])e seen that in leaves having stomata 

 on both surfaces the ratio of carbon dioxide emitted follows very closely 

 the ratio of the distribution of the stomata on the two surfaces. It seems 



"Brown and Escombe, Proc. Roy. Soc. Lo)tdon, B., 76, 61 (1905). 



