l86 CHAP. XXII. EFFICIENCY OF THE SPECTRAL RAYS 



of which a typical example is given below. The first column 

 in Table XXVI. gives the colour of the light, the second the 

 average bubbling-period, and the third the photosynthetic 

 activity in c.mm. O per hour. In order that the different 

 determinations given below may be easily compared with 

 each other, the maximum activity which is manifested 

 under red light is taken as ioo, and the other activities 

 proportionately. 



Table XXVI. 



-Showing Photosynthetic Activity under 

 Different Spectral Rays 



The results obtained with four different specimens, and 

 their mean, are summarised below. 



Table XXVII. — Giving Photosynthetic Activity of Four 

 Different Specimens 



The above results give a general idea of the relative 

 efficiency of the different rays ; there was not enough time 

 to determine the exact wave-length of the red light which 

 was most potent, for, as stated above, the determinations 



